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solec 002
Dieldrin
Dieldrin concentrations in Lake Michigan lake trout increased from a mean of 0.27 microg/g in 1970 to 0.58 m/g in 1979, then they declined to 0.17 m/g in 1986 and 0.18 mg/g in 1990. While concentrations varied between lakes, the pattern observed in Lake Michigan was also observed in Lakes Superior, Huron and Ontario, i.e., a general decline, but with peaks in 1979 and 1984. In Lake Erie walleye, mean dieldrin concentrations decreased from 0.10 mg/g in 1977 to 0.04 mg/g in 1982, then increased to 0.07 mg/g in 1984, then declined again to 0.03 mg/g in 1990. Between 1979 and 1990, mean dieldrin concentrations declined significantly in the top predator fish from lakes Michigan, Huron and Erie.
Dieldrin concentrations are well below the IJC objective of 0.3 mg/g in whole fish.
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Project X
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Physical Characteristics of the System
The magnitude of the Great Lakes water system is difficult to appreciate, even for those who live within the basin. The lakes contain about 23,000 km3 (5,500 cu. mi.) of water, covering a total area of 244,000 km2 (94,000 sq. mi.) The Great Lakes are the largest system of fresh, surface water on earth, containing roughly 18 percent of the world supply. Only the polar ice caps contain more fresh water.
In spite of their large size, the Great Lakes are sensitive to the effects of a wide range of pollutants. The sources of pollution include the runoff of soils and farm chemicals from agricultural lands, the waste from cities, discharges from industrial areas and leachate from disposal sites. The large surface area of the lakes also makes them vulnerable to direct atmospheric pollutants that fall with rain or snow and as dust on the lake surface.
Outflows from the Great Lakes are relatively small (less than 1 percent per year) in comparison with the total volume of water. Pollutants that enter the lakes - whether by direct discharge along the shores, through tributaries, from land use or from the atmosphere are retained in the system and become more concentrated with time. Also, pollutants remain in the system because of resuspension (or mixing back into the water) of sediment and cycling through biological food chains.
Because of the large size of the watershed, physical characteristics such as climate, soils and topography vary across the basin. To the north, the climate is cold and the terrain is dominated by a granite bedrock called the Canadian (or Laurentian) Shield consisting of Precambrian rocks under a generally thin layer of acidic soils. Conifers dominate the northern forests.
In the southern areas of the basin, the climate is much warmer. The soils are deeper with layers or mixtures of clays, silts, sands, gravels and boulders deposited as glacial drift or as glacial lake and river sediments. The lands are usually fertile and can be readily drained for agriculture. The original deciduous forests have given way to agriculture and sprawling urban development.
Although part of a single system, each lake is different. In volume, Lake Superior is the largest. It is also the deepest and coldest of the five. Superior could contain all the other Great Lakes and three more Lake Eries. Because of its size, Superior has a retention time of 172 years. Retention time is a measure based on the volume of water in the lake and the mean rate of outflow. Most of the Superior basin is forested, with little agriculture because of a cool climate and poor soils. The forests and sparse population result in relatively few pollutants entering Lake Superior, except through airborne transport.
Lake Michigan, the third largest in area, is the only Great Lake entirely within the United States. The northern part is in the colder, less developed upper Great Lakes region. It is sparsely populated, except for the Fox River Valley, which drains into Green Bay. This bay has one of the most productive Great Lakes fisheries but receives the wastes from the world's largest concentration of pulp and paper mills. The more temperate southern basin of Lake Michigan is among the most urbanized areas in the Great Lakes system. It contains the Milwaukee and Chicago metropolitan areas. This region is home to about 8 million people or about one-fifth of the total population of the Great Lakes basin. Fortunately for the lake, drainage for much of the Chicago area has been redirected out of the Great Lakes Basin.
Lake Huron, which includes Georgian Bay, is the third largest of the lakes by volume. Many Canadians and Americans own cottages on
the shallow, sandy beaches of Huron and along the rocky shores of
Georgian Bay. The Saginaw River basin is intensively farmed and
contains the Flint and Saginaw-Bay City metropolitan areas. Saginaw
Bay, like Green Bay, contains a very productive fishery.
Lake Erie is the smallest of the lakes in volume and is exposed to the greatest effects from urbanization and agriculture. Because of the fertile soils surrounding the lake, the area is intensively farmed. The lake receives runoff from the agricultural area of southwestern Ontario and parts of Ohio, Indiana and Michigan. Seventeen metropolitan areas with populations over 50,000 are located within the Lake Erie basin. Although the area of the lake is about 26,000 km2 (10,000 square miles), the average depth is only about 19 metres (62 feet). It is the shallowest of the five lakes and therefore warms rapidly in the spring and summer, and frequently freezes over in winter. It also has the shortest retention time of the lakes, 2.6 years. The western basin, comprising about one-fifth of the lake, is very shallow with an average depth of 7.4 metres (24 feet) and a maximum depth of 19 metres (62 feet).
Lake Ontario, although slightly smaller in area, is much deeper than its upstream neighbour, Lake Erie, with an average depth of 86 metres (283 feet) and a retention time of about 6 years. Major urban industrial centres, such as Hamilton and Toronto, are located on its shore. The U.S. shore is less urbanized and is not intensively farmed, except for a narrow band along the lake.
narrow band
along the lake.
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atlas029a
In spite of their large size, the Great Lakes are sensitive to the effects of a wide range of pollutants. The sources of pollution include the runoff of soils and farm chemicals from agricultural lands, the waste from cities, discharges from industrial areas and leachate from disposal sites. The large surface area of the lakes also makes them vulnerable to direct atmospheric pollutants that fall with rain or snow and as dust on the lake surface.
Outflows from the Great Lakes are relatively small (less than 1 percent per year) in comparison with the total volume of water. Pollutants that enter the lakes - whether by direct discharge along the shores, through tributaries, from land use or from the atmosphere are retained in the system and become more concentrated with time. Also, pollutants remain in the system because of resuspension (or mixing back into the water) of sediment
and cycling through biological food chains.
Because of the large size of the watershed, physical
characteristics such as climate, soils and topography vary across
the basin. To the north, the climate is cold and the terrain is
dominated by a granite bedrock called the Canadian (or Laurentian)
Shield consisting of Precambrian rocks under a generally thin layer
of acidic soils. Conifers dominate the northern forests.
In the southern areas of the basin, the climate is much warmer. The
soils are deeper with layers or mixtures of clays, silts, sands,
gravels and boulders deposited as glacial drift or as glacial lake
and river sediments. The lands are usually fertile and can be
readily drained for agriculture. The original deciduous forests
have given way to agriculture and sprawling urban development.
Although part of a single system, each lake is different. In
volume, Lake Superior is the largest. It is also the deepest and
coldest of the five. Superior could contain all the other Great
Lakes and three more Lake Eries. Because of its size, Superior has
a retention time of 172 years. Retention time is a measure based on
the volume of water in the lake and the mean rate of outflow. Most
of the Superior basin is forested, with little agriculture because
of a cool climate and poor soils. The forests and sparse population
result in relatively few pollutants entering Lake Superior, except
through airborne transport.
Lake Michigan, the second largest, is the only Great Lake entirely
within the United States. The northern part is in the colder, less
developed upper Great Lakes region. It is sparsely populated,
except for the Fox River Valley, which drains into Green Bay. This
bay has one of the most productive Great Lakes fisheries but
receives the wastes from the world's largest concentration of pulp
and paper mills. The more temperate southern basin of Lake Michigan
is among the most urbanized areas in the Great Lakes system. It
contains the Milwaukee and Chicago metropolitan areas. This region
is home to about 8 million people or about one-fifth of the total
population of the Great Lakes basin.
Lake Huron, which includes Georgian Bay, is the third largest of
the lakes by volume. Many Canadians and Americans own cottages on
the shallow, sandy beaches of Huron and along the rocky shores of
Georgian Bay. The Saginaw River basin is intensively farmed and
contains the Flint and Saginaw-Bay City metropolitan areas. Saginaw
Bay, like Green Bay, contains a very productive fishery.
Lake Erie is the smallest of the lakes in volume and is exposed to
the greatest effects from urbanization and agriculture. Because of
the fertile soils surrounding the lake, the area is intensively
farmed. The lake receives runoff from the agricultural area of
southwestern Ontario and parts of Ohio, Indiana and Michigan.
Seventeen metropolitan areas with populations over 50,000 are
located within the Lake Erie basin. Although the area of the lake
is about 26,000 km2 (10,000 square miles), the average depth is
only about 19 metres (62 feet). It is the shallowest of the five
lakes and therefore warms rapidly in the spring and summer, and
frequently freezes over in winter. It also has the shortest
retention time of the lakes, 2.6 years. The western basin,
comprising about one-fifth of the lake, is very shallow with an
average depth of 7.4 metres (24 feet) and a maximum depth of 19
metres (62 feet).
Lake Ontario, although slightly smaller in area, is much deeper
than its upstream neighbour, Lake Erie, with an average depth of 86
metres (283 feet) and a retention time of about 6 years. Major
urban industrial centres, such as Hamilton and Toronto, are located
on its shore. The U.S. shore is less urbanized and is not
intensively farmed, except for a narrow band along the lake.
tres (62 feet).
Lake Ontario, although slightly smaller in area, is much deeper
than its upstream neighbour, Lake Erie, with an average depth of 86
metres (283 feet) and a retention time of about 6 years. Major
urban industrial centres, such as Hamilton and Toronto, are located
on its shore. The U.S. shore is less urbanized and is not
intensively farmed, except for a narrow band along the lake.
for a narrow band along the lake.
for a narrow band along the lake.
farmed, except for a narrow band
along the lake.
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Although part of a single system, each lake is different. In volume, Lake Superior is the largest. It is also the deepest and coldest of the five. Superior could contain all the other Great Lakes and three more Lake Eries. Because of its size, Superior has a retention time of 172 years. Retention time is a measure based on the volume of water in the lake and the mean rate of outflow. Most of the Superior basin is forested, with little agriculture because of a cool climate and poor soils. The forests and sparse population result in relatively few pollutants entering Lake Superior, except through airborne transport.
Lake Michigan, the second largest, is the only Great Lake entirely within the United States. The northern part is in the colder, less developed upper Great Lakes region. It is sparsely populated, except for the Fox River Valley, which drains into Green Bay. This bay has one of the most productive Great Lakes fisheries but receives the wastes from the world's largest concentration of pulp and paper mills. The more temperate southern basin of Lake Michigan is among the most urbanized areas in the Great Lakes system. It contains the Milwaukee and Chicago metropolitan areas. This region is home to about 8 million people or about one-fifth of the total population of the Great Lakes basin.
Lake Huron, which includes Georgian Bay, is the third largest of the lakes by volume. Many Canadians and Americans own cottages on the shallow, sandy beaches of Huron and along the rocky shores of Georgian Bay. The Saginaw River basin is intensively farmed and contains the Flint and Saginaw-Bay City metropolitan areas. Saginaw Bay, like Green Bay, contains a very productive fishery.
Lake Erie is the smallest of the lakes in volume and is exposed to the greatest effects from urbanization and agriculture. Because of the fertile soils surrounding the lake, the area is intensively farmed. The lake receives runoff from the agricultural area of southwestern Ontario and parts of Ohio, Indiana and Michigan. Seventeen metropolitan areas with populations over 50,000 are located within the Lake Erie basin. Although the area of the lake is about 26,000 km2 (10,000 square miles), the average depth is only about 19 metres (62 feet). It is the shallowest of the five lakes and therefore warms rapidly in the spring and summer, and frequently freezes over in winter. It also has the shortest retention time of the lakes, 2.6 years. The western basin, comprising about one-fifth of the lake, is very shallow with an average depth of 7.4 metres (24 feet) and a maximum depth of 19 metres (62 feet).
Lake Ontario, although slightly smaller in area, is much deeper than its upstream neighbour, Lake Erie, with an average depth of 86 metres (283 feet) and a retention time of about 6 years. Major urban industrial centres, such as Hamilton and Toronto, are located on its shore. The U.S. shore is less urbanized and is not intensively farmed, except for a narrow band along the lake.
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GEOLOGY
The foundation for the present Great Lakes basin was set about 3 billion years ago, during the Precambrian Era. This era occupies about five-sixths of all geological time and was a period of great volcanic activity and tremendous stresses, which formed great mountain systems. Early sedimentary and volcanic rocks were folded and heated into complex structures. These were later eroded and, today, appear as the gently rolling hills and small mountain remnants of the Canadian Shield, which forms the northern and northwestern portions of the Great Lakes basin. Granitic rocks of the shield extend southward beneath the Paleozoic, sedimentary
rocks where they form the
basement
structure of the southern and
eastern portions of the basin.
With the coming of the Paleozoic Era, most of central North America was flooded again and again by marine seas, which were inhabited by a multitude of life forms, including corals, crinoids, brachiopods and mollusks. The seas deposited lime silts, clays, sand and salts, which eventually consolidated into limestone, shales, sandstone, halite and gypsum.
During the Pleistocene Epoch, the continental glaciers repeatedly advanced over the Great Lakes region from the north. The first glacier began to advance more than a million years ago. As they inched forward, the glaciers, up to 2,000 metres (6,500 feet) thick, scoured the surface of the earth, leveled hills, and altered forever the previous ecosystem. Valleys created by the river systems of the previous era were deepened and enlarged to form the basins for the Great Lakes. Thousands of years later, the climate began to warm, melting and slowly shrinking the glacier. This was followed by an interglacial period during which vegetation and
wildlife returned. The whole cycle was repeated several times.
Sand, silt, clay and boulders deposited by the glaciers occur in various mixtures and forms. These deposits are collectively referred to as - glacial drift - and include features such as moraines, which are linear mounds of poorly sorted material or
, flat till plains, till drumlins, and eskers formed of well-sorted sands and gravels deposited from meltwater. Areas
having substantial deposits of well-sorted sands and gravels (eskers, kames and outwash) are usually significant groundwater storage and transmission areas called "aquifers". These also serve as excellent sources of sand and gravel for commercial extraction.
As the glacier retreated, large volumes of meltwater occurred along the front of the ice. Because the land was greatly depressed at this time from the weight of the glacier, large glacial lakes formed. These lakes were much larger than the present Great Lakes. Their legacy can still be seen in the form of beach ridges, eroded bluffs and flat plains located hundreds of metres above present lake levels. Glacial lake plains known as
lacustrine plains - occur around Saginaw Bay and west and north of Lake Erie.
As the glacier receded, the land began to rise. This uplift (at times relatively rapid) and the shifting ice fronts caused dramatic changes in the depth, size and drainage patterns of the glacial lakes. Drainage from the lakes occurred variously through the Illinois River Valley (towards the Mississippi River), the Hudson River Valley, the Kawartha Lakes (Trent River) and the Ottawa River Valley before entering their present outlet through the St. Lawrence River Valley. Although the uplift has slowed considerably, it is still occurring in the northern portion of the basin. This, along with changing long-term weather patterns, suggests that the lakes are not static and will continue to evolve.......
Pleistocene Epoch
Cenozoic Era
Mesozoic Era
Paleozoic Era
Precambrian Era
Present
63 Million Years
230 Million Years
600 Million Years
Approximate Time Since Start Of Period
3 Billion Years
The foundation for the present Great Lakes basin was
set about three billion years ago during the Precambrian Era.
This era occupies about five-sixths of all geological time and
was a period of great volcanic activity and tremendous stresses
which formed great mountain systems. Early sedimentary and
volcanic rocks were folded and heated into complex structures.
These were later eroded and, today, appear as the gently rolling
hills and small mountain remnants of the Canadian Shield which
forms the northern and northwestern portions of the Great Lakes
basin. Granitic rocks of the shield extend southward beneath the
Palaeozoic, sedimentary rocks where they form the 'basement'
structure of the southern and eastern portions of the basin.
With the coming of the Palaeozoic Era, most of central North
America was flooded again and again by marine seas which were
inhabited by a multitude of life forms, including corals,
crinoids, brachiopods and mollusks. The seas deposited lime
silts, clays, sand and salts which eventually consolidated into
limestone, shales, sandstone, halite and gypsum.
During the Pleistocene epoch, the continental glaciers
repeatedly advanced over the Great Lakes region from the north.
The first glacier began to advance more than a million years ago.
As they inched forward, the glaciers, up to 2,000 meters (6,500
feet) thick, scoured the surface of the earth, levelled hills,
and altered forever the previous ecosystem. Valleys created by
the river systems of the previous era were deepened and enlarged
to form the basins for the Great Lakes. Thousands of years
later, the climate began to warm, melting and slowly shrinking
the glacier. This was followed by an interglacial period during
which vegetation and wildlife returned. The whole cycle was
repeated several times.
Sand, silt, clay and boulders deposited by the glacier occur
in various mixtures and forms. These deposits are collectively
referred to as 'glacial drift' and include features such as
moraines, which are linear mounds of poorly sorted material or
'till', flat till plains, till drumlins, and eskers formed of
well-sorted sands and gravels deposited from meltwater. Areas
having substantial deposits of well-sorted sands and gravels
(eskers, kames and outwash) are usually significant groundwater
storage and transmission areas called 'aquifers'. These also
serve as excellent sources of sand and gravel for commercial
extraction.
As the Glacier retreated, large volumes of meltwater
occurred along the front of the ice. Because the land was greatly
depressed at this time from the weight of the glacier, large
glacial lakes formed. These lakes were much larger than the
present Great Lakes. Their legacy can still be seen in the form
of beach ridges, eroded bluffs and flat plains located hundreds
of meters above present lake levels. Glacial lake plains known
as lacustrine plains, occur around Saginaw Bay and west and north
of Lake Erie.
As the glacier receded the land began to rise. This
uplift (at times relatively rapid) and the shifting ice fronts
caused dramatic changes in the depth, size and drainage patterns
of the glacial lakes. Drainage from the lakes occurred variously
through the Illinois River Valley (towards the Mississippi
River), the Hudson River Valley, the Kawartha Lakes (Trent River)
and the Ottawa River Valley before entering their present outlet
through the St. Lawrence River Valley. Although the uplift has
slowed considerably, it is still occurring in the northern
portion of the basin. This, along with changing long term weather
patterns suggest that the lakes are not static and will continue
to evolve.
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atlas031
Climate
The weather in the Great Lakes basin is affected by three factors: air masses from other regions, the location of the basin within a large continental landmass, and the moderating influence of the lakes themselves. The prevailing movement of air is from the west. The characteristically changeable weather of the region is the result of alternating flows of warm, humid air from the Gulf of Mexico and cold, dry air from the Arctic.
In summer, the northern region around Lake Superior generally receives cool, dry air masses from the Canadian northwest. In the south, tropical air masses originating in the Gulf of Mexico are most influential. As the Gulf air crosses the lakes, the bottom layers remain cool while the top layers are warmed. Occasionally, the upper layer traps the cooler air below, which in turn traps moisture and airborne pollutants, and prevents them from rising and dispersing. This is called a temperature inversion and can result in dank, humid days in areas in the midst of the basin, such as Michigan and Southern Ontario, and can also cause smog in low-lying industrial areas.
Increased summer sunshine warms the surface layer of water in the
lakes, making it lighter than the colder water below. In the fall and winter months, release of the heat stored in the lakes moderates the climate near the shores of the lakes. Parts of Southern Ontario, Michigan and western New York enjoy milder winters than similar mid-continental areas at lower latitudes.
In the autumn, the rapid movement and occasional clash of warm and cold air masses through the region produce strong winds. Air temperatures begin to drop gradually and less sunlight, combined with increased cloudiness, signal more storms and precipitation. Late autumn storms are often the most perilous for navigation and shipping on the lakes.
In winter, the Great Lakes region is affected by two major air masses. Arctic air from the northwest is very cold and dry when it enters the basin, but is warmed and picks up moisture travelling over the comparatively warmer lakes. When it reaches the land, the moisture condenses as snow, creating heavy snowfalls on the lee side of the lakes in areas frequently referred to as snowbelts. For part of the winter, the region is affected by Pacific air masses that have lost much of their moisture crossing the western mountains. Less frequently, air masses enter the basin from the southwest, bringing in moisture from the Gulf of Mexico. This air is slightly warmer and more humid. During the winter, the temperature of the lakes continues to drop. Ice frequently covers Lake Erie but seldom fully covers the other lakes.
Spring in the Great Lakes region, like autumn, is characterized by variable weather. Alternating air masses move through rapidly, resulting in frequent cloud cover and thunderstorms. By early spring, the warmer air and increased sunshine begin to melt the snow and lake ice, starting again the thermal layering of the lakes. The lakes are slower to warm than the land and tend to keep adjacent land areas cool, thus prolonging cool conditions sometimes well into April. Most years, this delays the leafing and blossoming of plants, protecting tender plants, such as fruit trees, from late
frosts. This extended state of dormancy allows plants from somewhat
warmer climates to survive in the western shadow of the lakes. It is also the reason for the presence of vineyards in those areas.
areas.
in those areas.
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atlas0311
Spring in the Great Lakes region, like autumn, is characterized by variable weather. Alternating air masses move through rapidly, resulting in frequent cloud cover and thunderstorms. By early spring, the warmer air and increased sunshine begin to melt the snow and lake ice, starting again the thermal layering of the lakes. The lakes are slower to warm than the land and tend to keep adjacent land areas cool, thus prolonging cool conditions sometimes well into April. Most years, this delays the leafing and blossoming of plants, protecting tender plants, such as fruit trees, from late frosts. This extended state of dormancy allows plants from somewhat warmer climates to survive in the western shadow of the lakes. It is also the reason for the presence of vineyards in those areas.
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atlas032
Climate Change and The Great Lakes
At various times throughout its history, the Great Lakes basin has been covered by thick glaciers and tropical forests, but these changes occurred before humans occupied the basin. Present-day concern about the atmosphere is premised on the belief that society at large, through its means of production and modes of daily activity, especially by ever increasing carbon dioxide emissions, may be modifying the climate at a rate unprecedented in history.
The very prevalent greenhouse effect is actually a natural phenomenon. It is a process by which water vapour and carbon dioxide in the atmosphere absorb heat given off by the earth and radiate it back to the surface. Consequently the earth remains warm and habitable (16
C average world temperature rather than 18
C without the greenhouse effect). However, humans have increased the carbon dioxide present in the atmosphere since the industrial revolution from 280 parts per million to the present 350 ppm, and some predict that the concentration will reach twice its pre-industrial levels by the middle of the next century.
Climatologists, using the General Circulation Model (GCM), have been able to determine the manner in which the increase of carbon dioxide emissions will affect the climate in the Great Lakes basin. Several of these models exist and show that at twice the carbon dioxide level, the climate of the basin will be warmer by 2-4
C and slightly damper than at present. For example, Toronto's climate would resemble the present climate of southern Ohio. Warmer climates mean increased evaporation from the lake surfaces and evapotranspiration from the land surface of the basin. This in turn
will augment the percentage of precipitation that is returned to the atmosphere. Studies have shown that the resulting net basin supply, the amount of water contributed by each lake basin to the overall hydrologic system, will be decreased by 23 to 50 percent. The resulting decreases in average lake levels will be from half a metre to two metres, depending on the GCM used.
Large declines in lake levels would create large-scale economic concern for the commercial users of the water system. Shipping companies and hydroelectric power companies would suffer economic repercussions, and harbours and marinas would be adversely affected. While the precision of such projections remains uncertain, the possibility of their accuracy embraces important long-term implications for the Great Lakes.
The potential effects of climate change on human health in the Great Lakes region are also of concern, and researchers can only speculate as to what might occur. For example, weather disturbances, drought, and changes in temperature and growing season could affect crops and food production in the basin. Changes in air pollution patterns as a result of climate change could affect respiratory health, causing asthma, and new disease vectors and agents could migrate into the region.ts could migrate into the region.
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atlas034
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atlas033
The Hydrologic Cycle
Water is a renewable resource. It is continually replenished in ecosystems through the hydrologic cycle. Water evaporates in contact with dry air, forming water vapour. The vapour can remain as a gas, contributing to the humidity of the atmosphere; or it can condense and form water droplets, which, if they remain in the air, form fog and clouds. In the Great Lakes basin, much of the moisture in the region evaporates from the surface of the lakes. Other sources of moisture include the surface of small lakes and
tributaries, moisture on the land mass and water released by plants. Global movements of air also carry moisture into the basin, especially from the tropics.
Moisture-bearing air masses move through the basin and deposit their moisture as rain, snow, hail or sleet. Some of this precipitation returns to the atmosphere and some falls on the surfaces of the Great Lakes to become part of the vast quantity of stored fresh water once again. Precipitation that falls on the land returns to the lakes as surface runoff or infiltrates the soil and becomes groundwater.
Whether it becomes surface runoff or groundwater depends upon a number of factors. Sandy soils, gravels and some rock types contribute to groundwater flows, whereas clays and impermeable rocks contribute to surface runoff. Water falling on sloped areas tends to run off rapidly, while water falling on flat areas tends to be absorbed or stored on the surface. Vegetation also tends to decrease surface runoff; root systems hold moisture-laden soil readily, and water remains on plants.
Surface Run-off
Surface runoff is a a component of the hydrologic cycle. Rain falling on exposed soil tilled for agriculture or cleared for construction accelerates erosion and the transport of soil particles and pollutants into tributaries. Suspended soil particles in water are deposited as sediment in the lakes and often collect near the mouths of tributaries and connecting channels. Much of the sediment deposited in nearshore areas is resuspended and carried farther into the lake during storms. The finest particles (clays and silts) may remain in suspension long enough to reach the mid-lake areas.
Before settlement of the basin, streams typically ran clear year-round because natural vegetation prevented soil loss. Clearing of the original forest for agriculture and logging has resulted in both more erosion and runoff into the streams and lakes. This accelerated runoff aggravates flooding problems.
Groundwater
Groundwater is important to the Great Lakes ecosystem because it provides a reservoir for storing water and slowly replenishing the lakes in the form of base flow in the tributaries. It is also a source of drinking water for many communities in the Great Lakes basin. Shallow groundwater also provides moisture to plants.
As water passes through subsurface areas, some substances are filtered out, but some materials in the soils become dissolved or suspended in the water. Salts and minerals in the soil and bedrock are the source of what is referred to as
water, a common feature of well water in the lower Great Lakes basin.
Groundwater can also pick up materials of human origin that have been buried in dumps and landfill sites. Groundwater contamination problems can occur in both urban-industrial and agricultural areas. Protection and inspection of groundwater is essential to protect the quality of the entire water supply consumed by basin populations, because the underground movement of water is believed to be a major pathway for the transport of pollution to the Great Lakes. Groundwater may discharge directly to the lakes or indirectly as base flow to the tributaries..
tributaries.
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Groundwater
Groundwater is important to the Great Lakes ecosystem because it provides a reservoir for storing water and slowly replenishing the lakes in the form of base flow in the tributaries. It is also a source of drinking water for many communities in the Great Lakes basin. Shallow groundwater also provides moisture to plants.
As water passes through subsurface areas, some substances are filtered out, but some materials in the soils become dissolved or suspended in the water. Salts and minerals in the soil and bedrock are the source of what is referred to as
water, a common feature of well water in the lower Great Lakes basin.
Groundwater can also pick up materials of human origin that have been buried in dumps and landfill sites. Groundwater contamination problems can occur in both urban-industrial and agricultural areas. Protection and inspection of groundwater is essential to protect the quality of the entire water supply consumed by basin populations, because the underground movement of water is believed to be a major pathway for the transport of pollution to the Great Lakes. Groundwater may discharge directly to the lakes or indirectly as base flow to the tributaries.
utaries.
nd some rock types
contribute to groundwater flows, whereas clays and impermeable
rocks contribute to surface runoff. Water falling on sloped areas
tends to run off rapidly, while water falling on flat areas tends
to be absorbed or stored on the surface. Vegetation also tends to
decrease surface runoff; root systems hold moisture-laden soil
readily, and water remains on plants.
SURFACE RUN-OFF
Surface runoff is a a component of the hydrologic cycle. Rain falling on exposed soil tilled for agriculture or cleared for construction accelerates erosion and the transport of soil particles and pollutants into tributaries. Suspended soil particles in water are deposited as sediment in the lakes and often collect near the mouths of tributaries and connecting channels. Much of the sediment deposited in nearshore areas is resuspended and carried farther into the lake during storms. The finest particles (clays and silts) may remain in suspension long enough to reach the mid-lake areas.
Before settlement of the basin, streams typically ran clear
year-round because natural vegetation prevented soil loss. Clearing
of the original forest for agriculture and logging has resulted in
both more erosion and runoff into the streams and lakes. This
accelerated runoff aggravates flooding problems.
GROUNDWATER
Groundwater is important to the Great Lakes ecosystem because it
provides a reservoir for storing water and slowly replenishing the
lakes in the form of base flow in the tributaries. It is also a
source of drinking water for many communities in the Great Lakes
basin. Shallow groundwater also provides moisture to plants.
As water passes through subsurface areas, some substances are
filtered out, but some materials in the soils become dissolved or
suspended in the water. Salts and minerals in the soil and bedrock
are the source of what is referred to as
water, a common
feature of well water in the lower Great Lakes basin.
Groundwater can also pick up materials of human origin that have
been buried in dumps and landfill sites. Groundwater contamination
problems can occur in both urban-industrial and agricultural areas.
Protection and inspection of groundwater is essential to protect
the quality of the entire water supply consumed by basin
populations, because the underground movement of water is believed
to be a major pathway for the transport of pollution to the Great
Lakes. Groundwater may discharge directly to the lakes or
indirectly as base flow to the tributaries.
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atlas037
Wetlands
Wetlands are areas where the water table occurs above or near the land surface for at least part of the year. When open water is present, it must be less than two metres deep (seven feet), and stagnant or slow moving. The presence of excessive amounts of water in wetland regions has given rise to hydric soils, as well as encouraged the predominance of water tolerant (hydrophytic) plants and similar biological activity.
Four basic types of wetland are encountered in the Great Lakes basin: swamps, marshes, bogs and fens. Swamps are areas where trees and shrubs live on wet, organically rich mineral soils that are flooded for part or all of the year. Marshes develop in shallow standing water such as ponds and protected bays. Aquatic plants (such as species of rushes) form thick stands, which are rooted in sediments or become floating mats where the water is deeper. Swamps and marshes occur most frequently in the southern and eastern portions of the basin.
Bogs form in shallow stagnant water. The most characteristic plant species are the sphagnum mosses, which tolerate conditions that are too acidic for most other organisms. Dead sphagnum decomposes very slowly, accumulating in mats that may eventually become many metres thick and form a dome well above the original surface of the water. It is this material that is excavated and sold as peat moss. Peat also accumulates in fens. Fens develop in shallow, slowly moving water. They are less acidic than bogs and are usually fed by groundwater. Fens are dominated by sedges and grasses, but may include shrubs and stunted trees. Fens and bogs are commonly referred to as "peatlands" and occur most frequently in the cooler northern and northwestern portions of the Great Lakes basin.
Wetlands serve important roles ecologically, economically and socially to the overall health and maintenance of the Great Lakes ecosystem. They provide habitats for many kinds of plants and animals, some of which are found nowhere else. For ducks, geese and other migratory birds, wetlands are the most important part of the migratory cycle, providing food, resting places and seasonal habitats. Economically, wetlands play an essential role in sustaining a productive fishery. At least 32 of the 36 species of Great Lakes fish studied depend on coastal wetlands for their successful reproduction. In addition to providing a desirable habitat for aquatic life, wetlands prevent damage from erosion and flooding, as well as controlling point and nonpoint source pollution.
Coastal wetlands along the Great Lakes include some sites that are recognized internationally for their outstanding biological significance. Examples included the Long Point Complex and Point Pelee on the north shore of Lake Erie and the National Wildlife Area on Lake St. Clair. Long Point also was designated a UNESCO Biosphere Reserve. Wetlands of the lower Great Lakes region have also been identified as a priority of the Eastern Habitat Joint Venture of the North American Waterfowl Management Plan, an international agreement between governments and non-government
organizations (NGOs) to conserve highly significant wetlands.
Although wetlands are a fundamentally important element of the Great Lakes ecosystem and are of obvious merit, their numbers continue to decline at an alarming rate. Over two-thirds of the Great Lakes wetlands have already been lost and many of those remaining are threatened by development, drainage or pollution.lution.
pollution.
evelopment, drainage or pollution.
atlas016
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seiche
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B"seiche"
Lake Levels
The Great Lakes are part of the global hydrologic system. Prevailing westerly winds continuously carry moisture into the basin in air masses from other parts of the continent. At the same time, the basin loses moisture in departing air masses by evaporation and transpiration, and through the outflow of the St. Lawrence River. Over time, the quantity lost equals what is gained, but lake levels can vary substantially over short-term, seasonal
and long-term periods.
Day-to-day changes in water levels are caused by winds that push water on shore. This is called 'wind set-up' and is usually associated with a major lake storm, which may last for hours or days. Another extreme form of oscillation, known as a seiche, occurs with rapid changes in winds and barometric pressure.
Annual or seasonal variations in water levels are based mainly on changes in precipitation and runoff to the Great Lakes. Generally, the lowest levels occur in winter when much of the precipitation is locked up in ice and snow on land, and dry winter air masses pass over the lakes enhancing evaporation. Levels are highest in summer after the spring thaw when runoff increases.
The irregular long-term cycles correspond to long-term trends in precipitation and temperature, the causes of which have yet to be adequately explained. Highest levels occur during periods of abundant precipitation and lower temperatures that decrease evaporation. During periods of high lake levels, storms cause considerable flooding and shoreline erosion, which often result in property damage. Much of the damage is attributable to intensive shore development, which alters protective dunes and wetlands, removes stabilizing vegetation, and generally reduces the ability of the shoreline to withstand the damaging effects of wind and waves.
The International Joint Commission, the binational agency established under the Boundary Waters Treaty of 1909 between Canada and the U.S., has the responsibility for regulation of flows on the St. Marys and the St. Lawrence Rivers. These channels have been altered by enlargement and placement of control works associated with deep-draft shipping. Agreements between the U.S. and Canada govern the flow through the control works on these connecting channels.
The water from Lake Michigan flows to Lake Huron through the Straits of Mackinac. These straits are deep and wide, resulting in Lakes Michigan and Huron standing at the same elevation. There are no artificial controls on the St. Clair and Detroit Rivers that could change the flow from the Michigan-Huron Lakes system into Lake Erie. The outflow of Lake Erie via the Niagara River is also uncontrolled, except for some diversion of water through the
Welland Canal. A large percentage of the Niagara River flow is diverted through hydroelectric power plants at Niagara Falls, but this diversion has no effect on lake levels.
Studies of possible further regulation of flows and lake levels have concluded that natural fluctuation is huge compared with the influence of existing control works. Further regulation by engineering systems could not be justified in light of the cost and other impacts. Just one inch (two and a half centimetres) of water on the surface of Lakes Michigan and Huron amounts to more than 36 billion cubic metres of water (about 1,260 billion cubic feet).bic feet).
as 180 species of
fish native to the Great Lakes. Those inhabiting the nearshore
areas included Smallmouth and Largemouth bass, Muskellunge,
Northern Pike and Channel Catfish. In the open water were lake
herring, blue pike, lake whitefish, walleye, sauger, freshwater
drum, lake trout and white bass. Because of the differences in
the characteristics of the lakes, the species composition varied
for each of the Great Lakes. Warm, shallow Lake Erie was the most
productive, while deep Superior was least productive.
Changes in the species composition of the Great Lakes
basin in the last 200 years have been the result of human
activities. Many native fish species have been lost by over
fishing, habitat destruction or the arrival of exotic or non-
native species, such as the lamprey and the alewife. Pollution,
especially in the form of nutrient loading and toxic
contaminants, has placed additional stresses on fish populations.
Other man-made stresses have altered reproductive conditions and
habitats, causing some varieties to migrate or perish. Still
other effects on lake life result from damming, canal building,
altering or polluting tributaries to the lakes in which spawning
takes place and where distinct ecosystems once thrived and
contributed to the larger basin ecosystem.
d energy in a balance between available
resources and the life that depends on those resources. In
ecosystems, including the Great Lakes basin, everything depends
on everything else and nothing is ever really wasted.
The ecosystem of the Great Lakes and the life supported
within it have continuously altered with time. Through periods of
climate change and glaciation, species moved in and out of the
region, some perished and others pioneered under changed
circumstances. None of the changes, however, has been as rapid as
that which occurred with the arrival of European settlers.
When the first Europeans arrived in the basin nearly 400
years ago, it was a lush, thickly vegetated area. Vast timber
stands, consisting of oaks, maples and other hardwoods dominated
the southern areas. Only a very few, small vestiges of the
original forest remain today. Between the wooded areas were rich
grasslands with growth as high as two or three meters (seven to
10 feet). In the north, coniferous forests occupied the shallow,
sandy soils, interspersed by bogs and other wetlands.
The forest and grasslands supported a wide variety of
life, such as moose in the wetlands and coniferous woods, and
deer in the grasslands and brush forests of the south. The many
waterways and wetlands were home to beaver and muskrat which,
with the fox, wolf and other fur-bearing species, inhabited the
mature forestlands. These were trapped and traded as commodities
by the natives and the Europeans. Abundant bird populations
thrived on the various terrains, some migrating to the south in
winter, others making permanent homes in the basin.
It is estimated that there were as many as 180 species of
fish native to the Great Lakes. Those inhabiting the nearshore
areas included Smallmouth and Largemouth bass, Muskellunge,
Northern Pike and Channel Catfish. In the open water were lake
herring, blue pike, lake whitefish, walleye, sauger, freshwater
drum, lake trout and white bass. Because of the differences in
the characteristics of the lakes, the species composition varied
for each of the Great Lakes. Warm, shallow Lake Erie was the most
productive, while deep Superior was least productive.
Changes in the species composition of the Great Lakes
basin in the last 200 years have been the result of human
activities. Many native fish species have been lost by over
fishing, habitat destruction or the arrival of exotic or non-
native species, such as the lamprey and the alewife. Pollution,
especially in the form of nutrient loading and toxic
contaminants, has placed additional stresses on fish populations.
Other man-made stresses have altered reproductive conditions and
habitats, causing some varieties to migrate or perish. Still
other effects on lake life result from damming, canal building,
altering or polluting tributaries to the lakes in which spawning
takes place and where distinct ecosystems once thrived and
contributed to the larger basin ecosystem.
processes to break
down accumulated biomass (plants, animals and their wastes) into
the constituent materials and nutrients from which they
originated. Decomposition involves micro-organisms that are
essential to the ecosystem because they recycle matter which can
be used again.
Stable ecosystems are sustained by the interactions that
cycle nutrients and energy in a balance between available
resources and the life that depends on those resources. In
ecosystems, including the Great Lakes basin, everything depends
on everything else and nothing is ever really wasted.
The ecosystem of the Great Lakes and the life supported
within it have continuously altered with time. Through periods of
climate change and glaciation, species moved in and out of the
region, some perished and others pioneered under changed
circumstances. None of the changes, however, has been as rapid as
that which occurred with the arrival of European settlers.
When the first Europeans arrived in the basin nearly 400
years ago, it was a lush, thickly vegetated area. Vast timber
stands, consisting of oaks, maples and other hardwoods dominated
the southern areas. Only a very few, small vestiges of the
original forest remain today. Between the wooded areas were rich
grasslands with growth as high as two or three meters (seven to
10 feet). In the north, coniferous forests occupied the shallow,
sandy soils, interspersed by bogs and other wetlands.
The forest and grasslands supported a wide variety of
life, such as moose in the wetlands and coniferous woods, and
deer in the grasslands and brush forests of the south. The many
waterways and wetlands were home to beaver and muskrat which,
with the fox, wolf and other fur-bearing species, inhabited the
mature forestlands. These were trapped and traded as commodities
by the natives and the Europeans. Abundant bird populations
thrived on the various terrains, some migrating to the south in
winter, others making permanent homes in the basin.
It is estimated that there were as many as 180 species of
fish native to the Great Lakes. Those inhabiting the nearshore
areas included Smallmouth and Largemouth bass, Muskellunge,
Northern Pike and Channel Catfish. In the open water were lake
herring, blue pike, lake whitefish, walleye, sauger, freshwater
drum, lake trout and white bass. Because of the differences in
the characteristics of the lakes, the species composition varied
for each of the Great Lakes. Warm, shallow Lake Erie was the most
productive, while deep Superior was least productive.
Changes in the species composition of the Great Lakes
basin in the last 200 years have been the result of human
activities. Many native fish species have been lost by over
fishing, habitat destruction or the arrival of exotic or non-
native species, such as the lamprey and the alewife. Pollution,
especially in the form of nutrient loading and toxic
contaminants, has placed additional stresses on fish populations.
Other man-made stresses have altered reproductive conditions and
habitats, causing some varieties to migrate or perish. Still
other effects on lake life result from damming, canal building,
altering or polluting tributaries to the lakes in which spawning
takes place and where distinct ecosystems once thrived and
Day-to-day changes in water levels are caused by winds that push water on shore. This is called 'wind set-up' and is usually associated with a major lake storm, which may last for hours or days. Another extreme form of oscillation, known as a seiche, occurs with rapid changes in winds and barometric pressure.
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The International Joint Commission, the binational agency established under the Boundary Waters Treaty of 1909 between Canada and the U.S., has the responsibility for regulation of flows on the St. Marys and the St. Lawrence Rivers. These channels have been altered by enlargement and placement of control works associated with deep-draft shipping. Agreements between the U.S. and Canada govern the flow through the control works on these connecting channels.
The water from Lake Michigan flows to Lake Huron through the Straits of Mackinac. These straits are deep and wide, resulting in Lakes Michigan and Huron standing at the same elevation. There are no artificial controls on the St. Clair and Detroit Rivers that could change the flow from the Michigan-Huron Lakes system into Lake Erie. The outflow of Lake Erie via the Niagara River is also uncontrolled, except for some diversion of water through the Welland Canal. A large percentage of the Niagara River flow is diverted through hydroelectric power plants at Niagara Falls, but this diversion has no effect on lake levels..................
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esses
stratification
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B"stratification"
Lake Processes: Stratification and Turnover
The Great Lakes are not simply large containers of uniformly mixed water. They are, in fact, highly dynamic systems with complex processes and a variety of subsystems that change seasonally and on longer cycles.
The stratification or layering of water in the lakes is due to density changes caused by changes in temperature. The density of water increases as temperature decreases until it reaches its maximum density at about 4 degree Celsius (39 degree Fahrenheit). This causes thermal stratification, or the tendency of deep lakes to form distinct layers in the summer months. Deep water is insulated from the sun and stays cool and more dense, forming a lower layer called the hypolimnion. Surface and nearshore waters are warmed by the sun, making them less dense so that they form a surface layer called the epilimnion. As the summer progresses, temperature differences increase between the layers. A thin middle layer, or
thermocline
, develops in which a rapid transition in temperature occurs.
The warm epilimnion supports most of the life in the lake. Algal production is greatest near the surface where the sun readily penetrates. The surface layer is also rich in oxygen, which is mixed into the water from the atmosphere. A second zone of high productivity exists just above the hypolimnion, due to upward diffusion of nutrients. The hypolimnion is less productive because it receives less sunlight. In some areas, such as the central basin of Lake Erie, it may lack oxygen because of decomposition of
organic matter.
In late fall, surface waters cool, become denser and descend, displacing deep waters and causing a mixing or turnover of the entire lake. In winter, the temperature of the lower parts of the lake approaches 4
Celsius (39
Fahrenheit), while surface waters are cooled to the freezing point and ice can form. As temperatures and densities of deep and shallow waters change with the warming of spring, another turnover may occur. However, in most cases the lakes remain mixed throughout the winter.
The layering and turnover of water annually are important for water quality. Turnover is the main way in which oxygen-poor water in the deeper areas of the lakes can be mixed with surface water containing more dissolved oxygen. This prevents anoxia, or complete oxygen depletion, of the lower levels of most of the lakes. However, the process of stratification during the summer also tends to restrict dilution of pollutants from effluents and land runoff.
During the spring warming period, the rapidly warming nearshore waters are inhibited from moving to the open lake by a thermal bar, a sharp temperature gradient that prevents mixing until the sun warms the open lake surface waters or until the waters are mixed by storms. Because the thermal bar holds pollutants nearshore, they are not dispersed to the open waters and can become more concentrated within the nearshore areas.........................ithin the nearshore areas.
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LAKE STRATIFICATION (LAYERING) AND TURNOVER. Heat from the sun
and changing seasons cause water in large lakes to stratify or form
layers. In winter, the ice cover stays at 0 C (32 F) and the
water remains warmer below the ice than in the air above. Water is
most dense at 4 C (39 F). In the spring turnover, warmer water
rises as the surface heats up. In fall, surface waters cool, become
denser and descend as heat is lost from the surface. In summer,
stratification is caused by a warming of surface waters, which form
a distinct layer called the epilimnion. This is separated from the
cooler and denser waters of the hypolimnion by the thermocline, a
layer of rapid temperature transition. Turnover distributes oxygen
annually throughout most of the lakes.
stratification
stratification
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,,,,,,,,
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2llllll222222llll222
2lllnl
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atlas036
sources
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Great Lakes Ecosystem
As an ecosystem, the Great Lakes basin is a unit of nature in which living organisms and nonliving things interact adaptively. An ecosystem is fuelled by the sun, which provides energy in the form of light and heat. This energy warms the earth, the water and the air, causing winds, currents, evaporation and precipitation. The light energy of the sun is essential for the photosynthesis of green plants in water and on land. Plants grow when essential nutrients such as phosphorus and nitrogen are present with oxygen, inorganic carbon and adequate water.
Plant material is consumed in the water by zooplankton, which graze
the waters for algae, and on land by plant-eating animals (herbivores). Next in the chain of energy transfer through the ecosystem are organisms that feed on other animals (carnivores) and those that feed on both animals and plants (omnivores). Together these levels of consumption constitute the food chain, or web, a system of energy transfers through which an ecological community consisting of a complex of species is sustained. The population of each species is determined by a system of checks and balances based on factors such as the availability of food and the presence of predators, including disease organisms.
Every ecosystem also includes numerous processes to break down accumulated biomass (plants, animals and their wastes) into the constituent materials and nutrients from which they originated. Decomposition involves micro-organisms that are essential to the ecosystem because they recycle matter that can be used again.
Stable ecosystems are sustained by the interactions that cycle nutrients and energy in a balance between available resources and the life that depends on those resources. In ecosystems, including the Great Lakes basin, everything depends on everything else and nothing is ever really wasted.
The ecosystem of the Great Lakes and the life supported within it have continuously altered with time. Through periods of climate change and glaciation, species moved in and out of the region; some perished and others pioneered under changed circumstances. None of the changes, however, has been as rapid as that which occurred with the arrival of European settlers.
When the first Europeans arrived in the basin nearly 400 years ago, it was a lush, thickly vegetated area. Vast timber stands, consisting of oaks, maples and other hardwoods dominated the southern areas. Only a very few small vestiges of the original forest remain today. Between the wooded areas were rich grasslands with growth as high as 2 or 3 metres (7 to 10 feet). In the north, coniferous forests occupied the shallow, sandy soils, interspersed by bogs and other wetlands.
The forest and grasslands supported a wide variety of life, such as moose in the wetlands and coniferous woods, and deer in the grasslands and brush forests of the south. The many waterways and wetlands were home to beaver and muskrat which, with the fox, wolf and other fur-bearing species, inhabited the mature forest lands. These were trapped and traded as commodities by the native people and the Europeans. Abundant bird populations thrived on the various terrains, some migrating to the south in winter, others making permanent homes in the basin.
It is estimated that there were as many as 180 species of fish indigenous to the Great Lakes. Those inhabiting the nearshore areas included smallmouth and largemouth bass, muskellunge, northern pike and channel catfish. In the open water were lake herring, blue pike, lake whitefish, walleye, sauger, freshwater drum, lake trout and white bass. Because of the differences in the characteristics of the lakes, the species composition varied for each of the Great Lakes. Warm, shallow Lake Erie was the most productive, while deep Superior was the least productive.
Changes in the species composition of the Great Lakes basin in the last 200 years have been the result of human activities. Many native fish species have been lost by overfishing, habitat destruction or the arrival of exotic or non-indigenous species, such as the lamprey and the alewife. Pollution, especially in the form of nutrient loading and toxic contaminants, has placed
additional stresses on fish populations. Other human-made stresses have altered reproductive conditions and habitats, causing some varieties to migrate or perish. Still other effects on lake life result from damming, canal building, altering or polluting tributaries to the lakes in which spawning takes place and where distinct ecosystems once thrived and contributed to the larger basin ecosystem............................................................er
basin ecosystem.
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The FOOD WEB is a simplified way of understanding the process by
which organisms in higher trophic levels gain energy by consuming
organisms at lower trophic levels. All energy in an ecosystem
originates with the sun. The solar energy is transformed by green
plants through a process of photosynthesis into stored chemical
energy. This is consumed by plant-eating animals, which are in turn
consumed as food. Humans are part of the food web. The concept of
the food web explains how some persistent contaminants accumulate in an ecosystem and become biologically magnified.
NOTE:
This is a simplified representation of the food web showing the
main pathways. Food (energy) moves in the direction of the arrows.
The driving force is sunlight. Depictions of the various organisms
are not to scale.
t. Depictions of the various organisms
are not to scale.
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As an ecosystem, the Great Lakes basin is a unit of nature in which living organisms and nonliving things interact adaptively. An ecosystem is fuelled by the sun, which provides energy in the form of light and heat. This energy warms the earth, the water and the air, causing winds, currents, evaporation and precipitation. The light energy of the sun is essential for the photosynthesis of green plants in water and on land. Plants grow when essential nutrients such as phosphorus and nitrogen are present with oxygen, inorganic carbon and adequate water.
Plant material is consumed in the water by zooplankton, which graze the waters for algae, and on land by plant-eating animals (herbivores). Next in the chain of energy transfer through the ecosystem are organisms that feed on other animals (carnivores) and those that feed on both animals and plants (omnivores). Together these levels of consumption constitute the food chain, or web, a system of energy transfers through which an ecological community consisting of a complex of species is sustained. The population of each species is determined by a system of checks and balances based on factors such as the availability of food and the presence of predators, including disease organisms.
Every ecosystem also includes numerous processes to break down accumulated biomass (plants, animals and their wastes) into the constituent materials and nutrients from which they originated. Decomposition involves micro-organisms that are essential to the ecosystem because they recycle matter that can be used again.
Stable ecosystems are sustained by the interactions that cycle nutrients and energy in a balance between available resources and the life that depends on those resources. In ecosystems, including the Great Lakes basin, everything depends on everything else and nothing is ever really wasted.
The ecosystem of the Great Lakes and the life supported within it have continuously altered with time. Through periods of climate change and glaciation, species moved in and out of the region; some perished and others pioneered under changed circumstances. None of the changes, however, has been as rapid as that which occurred with the arrival of European settlers....
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The FOOD WEB is a simplified way of understanding the process by
which organisms in higher trophic levels gain energy by consuming
organisms at lower trophic levels. All energy in an ecosystem
originates with the sun. The solar energy is transformed by green
plants through a process of photosynthesis into stored chemical
energy. This is consumed by plant-eating animals, which are in turn
consumed as food. Humans are part of the food web. The concept of
the food web explains how some persistent contaminants accumulate in an ecosystem and become biologically magnified.
NOTE:
This is a simplified representation of the food web showing the
main pathways. Food (energy) moves in the direction of the arrows.
The driving force is sunlight. Depictions of the various organisms
are not to scale.
t. Depictions of the various organisms
are not to scale.
welcome
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atlas001
Native People
The first inhabitants of the Great Lakes basin arrived about 10,000 years ago. They had crossed the land bridge from Asia or perhaps had reached South America across the vastness of the Pacific Ocean. Six thousand years ago, descendants of the first settlers were using copper from the south shore of Lake Superior and had established hunting and fishing communities throughout
the Great Lakes basin.
The native population in the Great Lakes area is estimated to have been between 60,000 and 117,000 in the 16th century when Europeans began their search for a passage to the Orient through the Great Lakes. The natives occupied widely scattered villages and grew corn, squash, beans and tobacco. These were moved once or twice in a generation when the resources in an area became exhausted.............
exhausted.
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Early Settlement by Europeans
By the early 1600s, the French had explored the forests around the St. Lawrence Valley and had begun to exploit the area for furs. The first area of the lakes to be visited by Europeans was Georgian Bay, reached via the Ottawa River and Lake Nipissing by the explorer Samuel de Champlain or perhaps Etienne Brule', one of Champlain's scouts, in 1615. To the south and east, the Dutch and English began to settle on the eastern seaboard of what is now the United States. Although a confederacy of five Indian nations
confined European settlement to the area east of the Appalachians, the French were able to establish bases in the lower St. Lawrence Valley. This enabled them to penetrate into the heart of the continent via the Ottawa River. In 1670, the French built the first of a chain of Great Lakes forts to protect the fur trade near the Mission of St. Ignace at the Straits of Mackinac. In 1673, Fort Frontenac, on the present site of Kingston, Ontario, became the first fort on the lower lakes.
Through the 17th century precious furs were transported to Hochelaga (Montreal) on the Great Lakes routes, but no permanent European settlements were maintained except at Forts Frontenac, Michilimackinac and Niagara. After Fort Oswego was established on the south shore of Lake Ontario by the British in 1727, settlement was encouraged in the Mohawk and other valleys leading toward the lakes. A showdown between the British and the French for control of the Great Lakes ended with the British capture of Quebec in 1759.
The British maintained control of the Great Lakes during the American Revolution and, at the close of the conflict, the Great Lakes became the boundary between the new U.S. republic and what remained of British North America. The British granted land to the Loyalists who fled the former New England colonies to Upper and Lower Canada, now the southern regions of the provinces of Ontario and Quebec, respectively. Between 1792 and 1800 the population of Upper Canada increased from 20,000 to 60,000. The new American government also moved to develop the Great Lakes region with the passage by Congress of the Ordinance of 1787. This legislation covered everything from land sale to provisions for statehood for the Northwest Territory, the area between the Great Lakes and the Ohio River west of Pennsylvania.
The final military challenge for the wealth of the Great Lakes region came with the War of 1812. For the Americans, the war was about the expansion into, and development of, the area around the lakes. For the British, it meant the defense of its remaining imperial holdings in North America. The war proved to be a short one - only 2 years - but final. When the shooting was over both the Americans and the British claimed victory.
Canada had survived invasion and was set on an inevitable course to nationhood. The new American nation had failed to conquer Upper Canada but gained needed national confidence and prestige. Native people, who had become involved in the war in order to secure a homeland, did not share in the victory. The winners in the War of 1812 were those who dreamed of settling the Great Lakes region. The long-awaited development of the area from a beautiful, almost uninhabited wilderness into a home and workplace for millions began in earnest.
rnest.
nest.
in earnest.
By the early 1600s, the French had explored the forests around
the St. Lawrence Valley and had begun to exploit the area for
furs. The first area of the lakes to be visited by Europeans was
Georgian Bay, reached via the Ottawa River and Lake Nipissing by
the explorer, Samuel de Champlain, or perhaps Etien Brule, one of
Champlain's scouts, in 1615. To the south and east, the Dutch
and English began to settle on the eastern seaboard of what is
now the United States. Although a confederacy of five Indian
nations confined European settlement to the area east of the
Appalachians, the French were able to establish bases in the
lower St. Lawrence Valley. This enabled them to penetrate into
the heart of the continent via the Ottawa River. In 1670 the
French built the first of a chain of Great Lakes forts to protect
the fur trade near the Mission of St. Ignace at the Straits of
Mackinac. In 1673, Fort Frontenac, on the present site of
Kingston, Ontario became the first fort on the lower lakes.
Through the 17th century precious furs were transported to
Hochelaga (Montreal) on the Great Lakes routes, but no permanent
European settlements were maintained except at forts Frontenac,
Michilimackinac and Niagara. After Fort Oswego was established on
the south shore of Lake Ontario by the British in 1727,
settlement was encouraged in the Mohawk and other valleys leading
toward the lakes. A showdown between the British and the French
for control of the Great Lakes ended with the British capture of
Quebec in 1758.
The British maintained control of the Great Lakes during
the American Revolution and, at the close of the conflict, the
Great Lakes became the boundary between the new U.S. republic and
what remained of British North America. The British granted land
to the Loyalists who fled the former New England colonies to
Upper and Lower Canada or what are now the southern regions of
the provinces of Ontario and Quebec, respectively. Between 1792
and 1800 the population of Upper Canada increased from 20,000 to
60,000. The new American government also moved to develop the
Great Lakes region with the passage by Congress of the Ordinance
of 1787. This legislation covered everything from land sale to
provisions for statehood for the Northwest Territory, the area
between the Great Lakes and the Ohio River west of Pennsylvania.
The final military challenge for the wealth of the Great
Lakes region came with the War of 1812. For the Americans the
war was about the expansion into, and development of, the area
around the lakes. For the British, it meant the defense of its
remaining imperial holdings in North America. The war proved to
be a short one - only two years - but final. When the shooting
was over both the Americans and the British claimed victory.
Canada had survived invasion and was set on an inevitable
course to nationhood. The new American nation had failed to
conquer Upper Canada but gained needed national confidence and
prestige. The natives, who had become involved in the war in
order to secure a homeland, did not share in the victory. The
winners in the War of 1812 were those who dreamed of settling the
Great Lakes region. The long-awaited development of the area
from a beautiful, almost uninhabited wilderness into a home and
workplace for millions began in earnest.
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@IPIu4
Agriculture
The promise of agricultural land was the greatest attraction to the immigrants to the Great Lakes region in the 19th century. By the mid-1800s, most of the Great Lakes region where farming was possible was settled. The population had swelled tremendously. There were about 400,000 people in Michigan, 300,000 in Wisconsin and perhaps half a million in Upper Canada.
Canals led to broader commodity export opportunities, allowing farmers to expand their operations beyond a subsistence level. Wheat and corn were the first commodities to be packed in barrels and shipped abroad. Grist mills - one of the region's first industries - were built on the tributaries flowing into the lakes to process the grains for overseas markets.
As populations grew, dairying and meat production for local consumption began to dominate agriculture in the Great Lakes basin. Specialty crops, such as fruit, vegetables and tobacco, grown for the burgeoning urban population, claimed an increasingly important share of the lands suitable for them.
The rapid, large-scale clearing of land for agriculture brought rapid changes in the ecosystem. Soils stripped of vegetation washed away to the lakes; tributaries and silty deltas clogged and altered the flow of the rivers. Fish habitats and spawning areas were destroyed. Greater surface runoff led to increased seasonal fluctuation in water levels and the creation of more flood-prone lands along the waterway. Agricultural development has also
contributed to Great Lakes pollution, chiefly in the form of eutrophication.
Modern row crop monoculture relies heavily on chemicals to control
pests such as insects, fungi and weeds. These chemicals are usually synthetic organic substances and they find their way to rivers and lakes to affect plant and animal life, and threaten human health. The problem was first recognized with DDT, a very persistent chemical, which tended to remain in the environment for a long time and to bioaccumulate through the food chain. It caused reproductive failures in some species of birds. Since the use of DDT was banned, some bird populations are now recovering. Other, less persistent, chemicals have replaced DDT and other problem pesticides, but toxic contamination from agricultural practices continues to be a concern. DDT levels in fish are declining but, in spite of being banned, some other pesticides, such as dieldrin, continue to persist in fish at relatively high levels.............................gh levels......ess persistent,
chemicals have replaced DDT and other problem pesticides, but toxic
contamination from agricultural practices continues to be a
concern. DDT levels in fish are declining but, in spite of being
banned, some other pesticides, such as dieldrin, continue to
persist in fish at relatively high levels......ely high levels.d today, as a result, the forests may be
a diminishing resource.
CANALS, SHIPPING AND TRANSPORTATION
Conflict over the Great Lakes continued after the War of
1812 in the form of competition to improve transportation routes.
By 1825 the 364-mile (586 km) Erie Canal, a waterway from Albany,
New York to Buffalo, was carrying settlers west and freight east.
The cost of goods in the West fell 90 per cent while the price of
agricultural products shipped through the lakes rose
dramatically. Settlement in the fertile expanses of Ohio and
Michigan became even more attractive.
The Canadians opened the Lachine Canal at about the same
time to bypass the worst rapids on the St. Lawrence River. In
1829, the Welland Canal joined lakes Erie and Ontario, bypassing
Niagara Falls. Other canals linked the Great Lakes to the Ohio
and Mississippi Rivers and the Great Lakes became the hub of
transportation in eastern North America.
Railroads replaced the canals after mid-century, making
still-important transportation links between the Great Lakes and
both seacoasts. In 1959, completion of the St. Lawrence Seaway
allowed modern ocean vessels to enter the lakes, but shipping has
not expanded as much as expected because of intense competition
from other modes of transportation such as trucking and
railroads.
Today, the three main commodities shipped on the Great
Lakes are iron ore, coal and grain. Transport of iron ore has
declined as some steel mills in the region have shut down or
reduced production, but steel-making capacity in North America is
likely to remain concentrated in the Great Lakes region. Coal
moves both east and west within the lakes, but coal export abroad
has not expanded as much as was anticipated during the rapid rise
of oil prices in the 1970s. As a result of economic decline the
Great Lakes mid-1980s fleet of over 300 vessels is being reduced
through the retirement of the older, smaller vessels.
on) contributed to the mercury pollution problem on the
Great Lakes until the early 1970s when mercury was banned from
use in the industry.
The logging industry was exploitive during its early
stages. Huge stands were lost in fires often because of poor
management of litter from logging operations. In Canada
lumbering was largely done on crown lands with a small tax
charged per tree. In the United States cutting was done on
private land but when it was cleared the owners often stopped
paying taxes and let the land revert to public ownership. In
both cases, clear-cutting was the usual practice. Without proper
rehabilitation of the forest, soils were readily eroded from
barren landscapes and lost to local streams, rivers and lakes.
In some areas of the Great Lakes basin, however, reforestation
has not been adequate and today, as a result, the forests may be
a diminishing resource.
CANALS, SHIPPING AND TRANSPORTATION
Conflict over the Great Lakes continued after the War of
1812 in the form of competition to improve transportation routes.
By 1825 the 364-mile (586 km) Erie Canal, a waterway from Albany,
New York to Buffalo, was carrying settlers west and freight east.
The cost of goods in the West fell 90 per cent while the price of
agricultural products shipped through the lakes rose
dramatically. Settlement in the fertile expanses of Ohio and
Michigan became even more attractive.
The Canadians opened the Lachine Canal at about the same
time to bypass the worst rapids on the St. Lawrence River. In
1829, the Welland Canal joined lakes Erie and Ontario, bypassing
Niagara Falls. Other canals linked the Great Lakes to the Ohio
and Mississippi Rivers and the Great Lakes became the hub of
transportation in eastern North America.
Railroads replaced the canals after mid-century, making
still-important transportation links between the Great Lakes and
both seacoasts. In 1959, completion of the St. Lawrence Seaway
allowed modern ocean vessels to enter the lakes, but shipping has
not expanded as much as expected because of intense competition
from other modes of transportation such as trucking and
railroads.
Today, the three main commodities shipped on the Great
Lakes are iron ore, coal and grain. Transport of iron ore has
declined as some steel mills in the region have shut down or
reduced production, but steel-making capacity in North America is
likely to remain concentrated in the Great Lakes region. Coal
moves both east and west within the lakes, but coal export abroad
has not expanded as much as was anticipated during the rapid rise
of oil prices in the 1970s. As a result of economic decline the
Great Lakes mid-1980s fleet of over 300 vessels is being reduced
through the retirement of the older, smaller vessels.
COMMERCIAL FISHERIES
Fish were important as food for the natives as well as for
the first European settlers. Commercial fishing began about 1820
and expanded about 20 per cent per year. The largest Great Lakes
fish harvests were recorded in 1889 and 1899 at some 67,000
tonnes (147 million pounds). However, by the 1880s some
preferred species in Lake Erie had declined. Catches increased
with more efficient fishing equipment but the golden days of the
commercial fishery were over by the late 1950s. Since then,
average annual catches have been around 50,000 tonnes (110
million pounds). The value of the commercial fishery has
declined drastically because the more valuable, larger fish have
given way to small and relatively low-value species. Over-
fishing, pollution, shoreline and stream habitat destruction, and
accidental and deliberate introduction of exotic species such as
the sea lamprey all played a part in the decline of the fishery.
Today, lake trout, sturgeon, and lake herring survive in
vastly reduced numbers and have been replaced by introduced
species such as smelt, alewife, splake, and Pacific salmon.
Populations of some of the native species such as yellow perch,
walleye and white bass have made good recovery. Lake trout, once
the top predator in the lakes, survives in sufficient numbers to
allow commercial fishing only in Lake Superior, the only lake
where substantial natural reproduction still occurs. However,
even in Superior, hatchery reared trout are stocked annually to
maintain the population.
Commercial fishing is under continuing pressure from
several fronts. Toxic contaminants could cause the closure of
additional fisheries as the ability to measure the presence of
chemicals improves together with the knowledge of their effects
on human health.
In addition to the lake trout, lake whitefish, blue pike
of Lake Erie, and the Atlantic salmon of Lake Ontario were the
top predators in the open waters of the lakes and were major
components of the commercial fishery in earlier times. Of the
three, the blue pike and Lake Ontario salmon are believed to be
extinct. The lake whitefish survives in sufficient numbers to
support commercial fishing only in Lake Superior and parts of
lakes Michigan and Huron. Currently, hatchery-reared coho and
chinook salmon are the most plentiful top predators in the open
lakes except in the western portion of Lake Erie which is
dominated by walleye.
Only pockets remain of the once large commercial fishery.
The Canadian commercial fishery in Lake Erie remains prosperous.
In 1991, 750 Canadian fishermen harvested a total of about 2300
tonnes (50 million pounds) {16,000 tonnes (36.2 million pounds)}
with a landed value of about $59 million (Canadian). For Canada,
the Lake Erie fishery represents nearly two-thirds of the total
Great Lakes harvest. All commercial fish caught in Canada are
inspected prior to market for quality and compliance with federal
regulations.
In the United States, the commercial fishery is based on
lake whitefish, smelt and perch, and on alewife for animal feed.
Commercial fishing is limited by a federal prohibition on the
sale of fish affected by toxic contaminants. Pressure to limit
commercial fishing in the U.S. is also exerted by sport fishing
groups anxious to manage the fishery in their interests. In
addition, the trend in the U.S. is to reduce the pressure on the
fishery by restricting commercial fishing to trapnets that
harvest species selectively, without killing species preferred by
recreational fishermen.
SPORT FISHERY
Several factors have contributed to the success of the
sport fisheries. The sea lamprey, which almost destroyed the
lake trout population, is being successfully controlled using
chemical lampricides. Walleye populations rebounded in Lake Erie
due to regulation of the commercial fishery and improvements in
water quality. The population of alewife exploded as lamprey
destroyed native top predators. The increase in alewife provided
a forage base for new predators such as coho and chinook salmon
which were introduced in the 1960s when lamprey populations
declined.
The sport fishery developed quickly as the Pacific salmon
rapidly grew to large size after they were introduced into Lake
Michigan. Charter fleets developed and a minor tourist boom led
to plans to develop a large fish stocking program to fuel a new
sport fishing industry.
By 1980, the idea of stocking exotic fish such as salmon
to support the sport fishery had spread to all the lakes and
jurisdictions. Ontario and Michigan also experimented with the
'splake', a hybrid of the native lake trout and brook (or
speckled) trout. None of these predators has been able to
reproduce very well if at all, so the fishery has been maintained
by stocking year after year. Ironically, the exception is the
pink salmon, a small species accidentally introduced to Lake
Superior in 1955, that survived to establish spawning
populations. They spread through lakes Michigan and Huron, where
they established self-propagating populations by the 1980s.
RECREATION
Since early in the industrial age, the waterways, shorelines
and woodlands of the Great lakes region have been attractions for
leisure time activities. Many of the utilitarian activities that
were so important in the early settlement and industrial
development became recreational activities in later years. For
example, boating, fishing, and canoeing were once commercial
activities, but are now primarily leisure pursuits.
Recreation in the area became an important economic and
social activity with the age of travel in the 19th century. A
thriving pleasure-boat industry based on the newly constructed
canals developed, bringing people into the region in conjunction
with rail and road travel. Niagara Falls attracted travellers
from considerable distances and was one of the first stimulants
to the growth of a leisure-related economy. Later, the
reputation of the lower lakes region as the frontier of a
pristine wilderness drew people seeking restful cures and miracle
waters to the many spas and 'clinics' which developed along the
waterway.
In the 20th century, more people had more free time. With
industrial growth, greater personal disposable income and shorter
work weeks, people of all walks of life began to spend their
leisure time beyond the city limits. Governments on both sides
of the border acquired lands and began to develop an extensive
system of parks, wilderness areas and conservation areas in order
to protect valuable local resources and to serve the needs of the
population for recreation areas. Unfortunately, by the time the
need for publicly accessible recreation lands had become
apparent, much of the land in the basin, including virtually all
the shoreline on the lower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
g as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
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Fertilizers that reach waterways in soils and runoff stimulate growth of algae and other water plants. The plants die and decay, depleting the oxygen in the water. Lack of oxygen leads to fish kills, and the character of the ecosystem changes as the original plants and animals give way to more pollution-tolerant species......
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Logging and Forestry
The original logging operations in the Great Lakes basin involved clearing the land for agriculture and building houses and barns for the settlers. Much of the wood was simply burned. By the 1830s, however, commercial logging began in Upper Canada. A few years later logging began in Michigan, and operations in Minnesota and Wisconsin soon followed.
Once again the lakes played a vital role. Cutting was generally done in the winter months by men from the farms. They travelled up the rivers felling trees that were floated down to the lakes during the spring thaw. The logs were formed into huge rafts or loosely gathered in booms to be towed by steam tugs. This latter practice had to be stopped because logs often escaped the boom and seriously interfered with shipping. In time, timber was carried in ships specially designed for log transport.
The earliest loggers mainly harvested white pine. In virgin stands these trees reached 60 metres (200 feet) in height, and a single tree could contain 10 cubic metres (6,000 board feet) of lumber. It was light and strong and much in demand for shipbuilding and construction. Each year, loggers had to move farther west and north in search of white pine. The trees were hundreds of years old and so were not soon replaced. When the resource was exhausted, lumbermen had to utilize other species. The hardwoods such as maple, walnut and oak were cut to make furniture, barrels and
specialty products.
Paper-making from pulpwood developed slowly. The first sulfite process paper mill was built on the Welland Canal in the 1860s. Paper production developed at Green Bay in the U.S. and elsewhere in the Great Lakes basin. Eventually Canada and the U.S. became the world
s leading producers of pulp and paper products. Today much of this production still occurs in the Great Lakes area. The pulp and paper industry (along with chloralkali production) contributed to the mercury pollution problem on the Great Lakes until the early 1970s, when mercury was banned from use in the industry.
The logging industry was exploitive during its early stages. Huge stands were lost in fires, often because of poor management of litter from logging operations. In Canada, lumbering was largely done on crown lands with a small tax charged per tree. In the United States, cutting was done on private land but when it was cleared, the owners often stopped paying taxes and let the land revert to public ownership. In both cases, clear-cutting was the
usual practice. Without proper rehabilitation of the forest, soils were readily eroded from barren landscapes and lost to local streams, rivers and lakes. In some areas of the Great Lakes basin, reforestation has not been adequate and today, as a result, the forests may be a diminishing resource....................................minishing resource.g resource.nishing resource.
CANALS, SHIPPING AND TRANSPORTATION
Conflict over the Great Lakes continued after the War of
1812 in the form of competition to improve transportation routes.
By 1825 the 364-mile (586 km) Erie Canal, a waterway from Albany,
New York to Buffalo, was carrying settlers west and freight east.
The cost of goods in the West fell 90 per cent while the price of
agricultural products shipped through the lakes rose
dramatically. Settlement in the fertile expanses of Ohio and
Michigan became even more attractive.
The Canadians opened the Lachine Canal at about the same
time to bypass the worst rapids on the St. Lawrence River. In
1829, the Welland Canal joined lakes Erie and Ontario, bypassing
Niagara Falls. Other canals linked the Great Lakes to the Ohio
and Mississippi Rivers and the Great Lakes became the hub of
transportation in eastern North America.
Railroads replaced the canals after mid-century, making
still-important transportation links between the Great Lakes and
both seacoasts. In 1959, completion of the St. Lawrence Seaway
allowed modern ocean vessels to enter the lakes, but shipping has
not expanded as much as expected because of intense competition
from other modes of transportation such as trucking and
railroads.
Today, the three main commodities shipped on the Great
Lakes are iron ore, coal and grain. Transport of iron ore has
declined as some steel mills in the region have shut down or
reduced production, but steel-making capacity in North America is
likely to remain concentrated in the Great Lakes region. Coal
moves both east and west within the lakes, but coal export abroad
has not expanded as much as was anticipated during the rapid rise
of oil prices in the 1970s. As a result of economic decline the
Great Lakes mid-1980s fleet of over 300 vessels is being reduced
through the retirement of the older, smaller vessels.
COMMERCIAL FISHERIES
Fish were important as food for the natives as well as for
the first European settlers. Commercial fishing began about 1820
and expanded about 20 per cent per year. The largest Great Lakes
fish harvests were recorded in 1889 and 1899 at some 67,000
tonnes (147 million pounds). However, by the 1880s some
preferred species in Lake Erie had declined. Catches increased
with more efficient fishing equipment but the golden days of the
commercial fishery were over by the late 1950s. Since then,
average annual catches have been around 50,000 tonnes (110
million pounds). The value of the commercial fishery has
declined drastically because the more valuable, larger fish have
given way to small and relatively low-value species. Over-
fishing, pollution, shoreline and stream habitat destruction, and
accidental and deliberate introduction of exotic species such as
the sea lamprey all played a part in the decline of the fishery.
Today, lake trout, sturgeon, and lake herring survive in
vastly reduced numbers and have been replaced by introduced
species such as smelt, alewife, splake, and Pacific salmon.
Populations of some of the native species such as yellow perch,
walleye and white bass have made good recovery. Lake trout, once
the top predator in the lakes, survives in sufficient numbers to
allow commercial fishing only in Lake Superior, the only lake
where substantial natural reproduction still occurs. However,
even in Superior, hatchery reared trout are stocked annually to
maintain the population.
Commercial fishing is under continuing pressure from
several fronts. Toxic contaminants could cause the closure of
additional fisheries as the ability to measure the presence of
chemicals improves together with the knowledge of their effects
on human health.
In addition to the lake trout, lake whitefish, blue pike
of Lake Erie, and the Atlantic salmon of Lake Ontario were the
top predators in the open waters of the lakes and were major
components of the commercial fishery in earlier times. Of the
three, the blue pike and Lake Ontario salmon are believed to be
extinct. The lake whitefish survives in sufficient numbers to
support commercial fishing only in Lake Superior and parts of
lakes Michigan and Huron. Currently, hatchery-reared coho and
chinook salmon are the most plentiful top predators in the open
lakes except in the western portion of Lake Erie which is
dominated by walleye.
Only pockets remain of the once large commercial fishery.
The Canadian commercial fishery in Lake Erie remains prosperous.
In 1991, 750 Canadian fishermen harvested a total of about 2300
tonnes (50 million pounds) {16,000 tonnes (36.2 million pounds)}
with a landed value of about $59 million (Canadian). For Canada,
the Lake Erie fishery represents nearly two-thirds of the total
Great Lakes harvest. All commercial fish caught in Canada are
inspected prior to market for quality and compliance with federal
regulations.
In the United States, the commercial fishery is based on
lake whitefish, smelt and perch, and on alewife for animal feed.
Commercial fishing is limited by a federal prohibition on the
sale of fish affected by toxic contaminants. Pressure to limit
commercial fishing in the U.S. is also exerted by sport fishing
groups anxious to manage the fishery in their interests. In
addition, the trend in the U.S. is to reduce the pressure on the
fishery by restricting commercial fishing to trapnets that
harvest species selectively, without killing species preferred by
recreational fishermen.
SPORT FISHERY
Several factors have contributed to the success of the
sport fisheries. The sea lamprey, which almost destroyed the
lake trout population, is being successfully controlled using
chemical lampricides. Walleye populations rebounded in Lake Erie
due to regulation of the commercial fishery and improvements in
water quality. The population of alewife exploded as lamprey
destroyed native top predators. The increase in alewife provided
a forage base for new predators such as coho and chinook salmon
which were introduced in the 1960s when lamprey populations
declined.
The sport fishery developed quickly as the Pacific salmon
rapidly grew to large size after they were introduced into Lake
Michigan. Charter fleets developed and a minor tourist boom led
to plans to develop a large fish stocking program to fuel a new
sport fishing industry.
By 1980, the idea of stocking exotic fish such as salmon
to support the sport fishery had spread to all the lakes and
jurisdictions. Ontario and Michigan also experimented with the
'splake', a hybrid of the native lake trout and brook (or
speckled) trout. None of these predators has been able to
reproduce very well if at all, so the fishery has been maintained
by stocking year after year. Ironically, the exception is the
pink salmon, a small species accidentally introduced to Lake
Superior in 1955, that survived to establish spawning
populations. They spread through lakes Michigan and Huron, where
they established self-propagating populations by the 1980s.
RECREATION
Since early in the industrial age, the waterways, shorelines
and woodlands of the Great lakes region have been attractions for
leisure time activities. Many of the utilitarian activities that
were so important in the early settlement and industrial
development became recreational activities in later years. For
example, boating, fishing, and canoeing were once commercial
activities, but are now primarily leisure pursuits.
Recreation in the area became an important economic and
social activity with the age of travel in the 19th century. A
thriving pleasure-boat industry based on the newly constructed
canals developed, bringing people into the region in conjunction
with rail and road travel. Niagara Falls attracted travellers
from considerable distances and was one of the first stimulants
to the growth of a leisure-related economy. Later, the
reputation of the lower lakes region as the frontier of a
pristine wilderness drew people seeking restful cures and miracle
waters to the many spas and 'clinics' which developed along the
waterway.
In the 20th century, more people had more free time. With
industrial growth, greater personal disposable income and shorter
work weeks, people of all walks of life began to spend their
leisure time beyond the city limits. Governments on both sides
of the border acquired lands and began to develop an extensive
system of parks, wilderness areas and conservation areas in order
to protect valuable local resources and to serve the needs of the
population for recreation areas. Unfortunately, by the time the
need for publicly accessible recreation lands had become
apparent, much of the land in the basin, including virtually all
the shoreline on the lower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
welcome
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atlas006
Canals, Shipping and Transportation
Conflict over the Great Lakes continued after the War of 1812 in the form of competition to improve transportation routes. In the U.S. the 586 km (364 mile) Erie Canal, a waterway from Albany, New York, to Buffalo, was carrying settlers west and freight east by 1825. The cost of goods in the west fell 90 percent while the price of agricultural products shipped through the lakes rose dramatically. Settlement in the fertile expanses of Ohio and Michigan became even more attractive.
In Canada the Lachine Canal was opened at about the same time to bypass the worst rapids on the St. Lawrence River. In 1829, the Welland Canal joined Lakes Erie and Ontario, bypassing Niagara Falls. Other canals linked the Great Lakes to the Ohio and Mississippi Rivers, and the Great Lakes became the hub of transportation in eastern North America.
Railroads replaced the canals after mid-century, making still-important transportation links between the Great Lakes and both seacoasts. In 1959, completion of the St. Lawrence Seaway allowed modern ocean vessels to enter the lakes, but shipping has not expanded as much as expected because of intense competition from other modes of transportation such as trucking and railroads.
Today, the three main commodities shipped on the Great Lakes are iron ore, coal and grain. Transport of iron ore has declined as some steel mills in the region have shut down or reduced production, but steel-making capacity in North America is likely to remain concentrated in the Great Lakes region. Coal moves both east and west within the lakes, but coal export abroad has not expanded as much as was anticipated during the rapid rise of oil prices in the 1970s. As a result of economic decline, the Great Lakes fleet of over 300 vessels is being reduced through the retirement of the older, smaller vessels.ent of the older, smaller vessels. er vessels.
Conflict over the Great Lakes continued after the War of
1812 in the form of competition to improve transportation routes.
By 1825 the 364-mile (586 km) Erie Canal, a waterway from Albany,
New York to Buffalo, was carrying settlers west and freight east.
The cost of goods in the West fell 90 per cent while the price of
agricultural products shipped through the lakes rose
dramatically. Settlement in the fertile expanses of Ohio and
Michigan became even more attractive.
The Canadians opened the Lachine Canal at about the same
time to bypass the worst rapids on the St. Lawrence River. In
1829, the Welland Canal joined lakes Erie and Ontario, bypassing
Niagara Falls. Other canals linked the Great Lakes to the Ohio
and Mississippi Rivers and the Great Lakes became the hub of
transportation in eastern North America.
Railroads replaced the canals after mid-century, making
still-important transportation links between the Great Lakes and
both seacoasts. In 1959, completion of the St. Lawrence Seaway
allowed modern ocean vessels to enter the lakes, but shipping has
not expanded as much as expected because of intense competition
from other modes of transportation such as trucking and
railroads.
Today, the three main commodities shipped on the Great
Lakes are iron ore, coal and grain. Transport of iron ore has
declined as some steel mills in the region have shut down or
reduced production, but steel-making capacity in North America is
likely to remain concentrated in the Great Lakes region. Coal
moves both east and west within the lakes, but coal export abroad
has not expanded as much as was anticipated during the rapid rise
of oil prices in the 1970s. As a result of economic decline the
Great Lakes mid-1980s fleet of over 300 vessels is being reduced
through the retirement of the older, smaller vessels.
trout, lake whitefish, blue pike
of Lake Erie, and the Atlantic salmon of Lake Ontario were the
top predators in the open waters of the lakes and were major
components of the commercial fishery in earlier times. Of the
three, the blue pike and Lake Ontario salmon are believed to be
extinct. The lake whitefish survives in sufficient numbers to
support commercial fishing only in Lake Superior and parts of
lakes Michigan and Huron. Currently, hatchery-reared coho and
chinook salmon are the most plentiful top predators in the open
lakes except in the western portion of Lake Erie which is
dominated by walleye.
Only pockets remain of the once large commercial fishery.
The Canadian commercial fishery in Lake Erie remains prosperous.
In 1991, 750 Canadian fishermen harvested a total of about 2300
tonnes (50 million pounds) {16,000 tonnes (36.2 million pounds)}
with a landed value of about $59 million (Canadian). For Canada,
the Lake Erie fishery represents nearly two-thirds of the total
Great Lakes harvest. All commercial fish caught in Canada are
inspected prior to market for quality and compliance with federal
regulations.
In the United States, the commercial fishery is based on
lake whitefish, smelt and perch, and on alewife for animal feed.
Commercial fishing is limited by a federal prohibition on the
sale of fish affected by toxic contaminants. Pressure to limit
commercial fishing in the U.S. is also exerted by sport fishing
groups anxious to manage the fishery in their interests. In
addition, the trend in the U.S. is to reduce the pressure on the
fishery by restricting commercial fishing to trapnets that
harvest species selectively, without killing species preferred by
recreational fishermen.
SPORT FISHERY
Several factors have contributed to the success of the
sport fisheries. The sea lamprey, which almost destroyed the
lake trout population, is being successfully controlled using
chemical lampricides. Walleye populations rebounded in Lake Erie
due to regulation of the commercial fishery and improvements in
water quality. The population of alewife exploded as lamprey
destroyed native top predators. The increase in alewife provided
a forage base for new predators such as coho and chinook salmon
which were introduced in the 1960s when lamprey populations
declined.
The sport fishery developed quickly as the Pacific salmon
rapidly grew to large size after they were introduced into Lake
Michigan. Charter fleets developed and a minor tourist boom led
to plans to develop a large fish stocking program to fuel a new
sport fishing industry.
By 1980, the idea of stocking exotic fish such as salmon
to support the sport fishery had spread to all the lakes and
jurisdictions. Ontario and Michigan also experimented with the
'splake', a hybrid of the native lake trout and brook (or
speckled) trout. None of these predators has been able to
reproduce very well if at all, so the fishery has been maintained
by stocking year after year. Ironically, the exception is the
pink salmon, a small species accidentally introduced to Lake
Superior in 1955, that survived to establish spawning
populations. They spread through lakes Michigan and Huron, where
they established self-propagating populations by the 1980s.
RECREATION
Since early in the industrial age, the waterways, shorelines
and woodlands of the Great lakes region have been attractions for
leisure time activities. Many of the utilitarian activities that
were so important in the early settlement and industrial
development became recreational activities in later years. For
example, boating, fishing, and canoeing were once commercial
activities, but are now primarily leisure pursuits.
Recreation in the area became an important economic and
social activity with the age of travel in the 19th century. A
thriving pleasure-boat industry based on the newly constructed
canals developed, bringing people into the region in conjunction
with rail and road travel. Niagara Falls attracted travellers
from considerable distances and was one of the first stimulants
to the growth of a leisure-related economy. Later, the
reputation of the lower lakes region as the frontier of a
pristine wilderness drew people seeking restful cures and miracle
waters to the many spas and 'clinics' which developed along the
waterway.
In the 20th century, more people had more free time. With
industrial growth, greater personal disposable income and shorter
work weeks, people of all walks of life began to spend their
leisure time beyond the city limits. Governments on both sides
of the border acquired lands and began to develop an extensive
system of parks, wilderness areas and conservation areas in order
to protect valuable local resources and to serve the needs of the
population for recreation areas. Unfortunately, by the time the
need for publicly accessible recreation lands had become
apparent, much of the land in the basin, including virtually all
the shoreline on the lower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
ower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
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bErEu4
Commercial Fisheries
Fish were important as food for the region's native people, as well as for the first European settlers. Commercial fishing began about 1820 and expanded about 20 percent per year. The largest Great Lakes fish harvests were recorded in 1889 and 1899 at some 67,000 tonnes (147 million pounds). However, by the 1880s some preferred species in Lake Erie had declined. Catches increased with more efficient fishing equipment but the golden days of the commercial fishery were over by the late 1950s. Since then, average annual catches have been around 50,000 tonnes (110 million pounds). The value of the commercial fishery has declined drastically because the more valuable, larger fish have given way to small and
relatively low-value species. Over-fishing, pollution, shoreline and stream habitat destruction, and accidental and deliberate introduction of exotic species such as the sea lamprey all played a part in the decline of the fishery.
Today, lake trout, sturgeon and lake herring survive in vastly reduced numbers and have been replaced by introduced species such as smelt, alewife, splake, and Pacific salmon. Populations of some of the native species such as yellow perch, walleye and white bass have made good recovery. Lake trout, once the top predator in the lakes, survives in sufficient numbers to allow commercial fishing only in Lake Superior, the only lake where substantial natural reproduction still occurs. However, even in Superior, hatchery-reared trout are stocked annually to maintain the population.
In addition to the lake trout, the blue pike of Lake Erie, and the Atlantic salmon of Lake Ontario were top predators in the open waters of the lakes and were major components of the commercial fishery in earlier times. Of the three, the blue pike and Lake Ontario Atlantic salmon are believed to be extinct. Currently, hatchery-reared coho and chinook salmon are the most plentiful top predators in the open lakes except in the western portion of Lake
Erie, which is dominated by walleye.
Only pockets remain of the once large commercial fishery. The Canadian commercial fishery in Lake Erie remains prosperous. In 1991, 750 Canadian fishermen harvested a total of about 2,300 tonnes (50 million pounds) with a landed value of about $59 million (Canadian). For Canada, the Lake Erie fishery represents nearly two-thirds of the total Great Lakes harvest. All commercial fish caught in Canada are inspected prior to market for quality and compliance with federal regulations.
In the United States, the commercial fishery is based on lake whitefish, smelt, bloater chubs and perch, and on alewife for animal feed. Commercial fishing is limited by a federal prohibition on the sale of fish affected by toxic contaminants. Pressure to limit commercial fishing in the U.S. is also exerted by sport fishing groups anxious to manage the fishery in their interests. In addition, the trend in the U.S. is to reduce the pressure on the
fishery by restricting commercial fishing to trapnets that harvest species selectively, without killing species preferred by recreational fishermen.
Commercial fishing is under continuing pressure from several fronts. Toxic contaminants could cause the closure of additional fisheries as the ability to measure the presence of chemicals improves together with the knowledge of their effects on human health..........................................s on human
health. human
health. is to reduce the pressure on the
fishery by restricting commercial fishing to trapnets that
harvest species selectively, without killing species preferred by
recreational fishermen.
SPORT FISHERY
Several factors have contributed to the success of the
sport fisheries. The sea lamprey, which almost destroyed the
lake trout population, is being successfully controlled using
chemical lampricides. Walleye populations rebounded in Lake Erie
due to regulation of the commercial fishery and improvements in
water quality. The population of alewife exploded as lamprey
destroyed native top predators. The increase in alewife provided
a forage base for new predators such as coho and chinook salmon
which were introduced in the 1960s when lamprey populations
declined.
The sport fishery developed quickly as the Pacific salmon
rapidly grew to large size after they were introduced into Lake
Michigan. Charter fleets developed and a minor tourist boom led
to plans to develop a large fish stocking program to fuel a new
sport fishing industry.
By 1980, the idea of stocking exotic fish such as salmon
to support the sport fishery had spread to all the lakes and
jurisdictions. Ontario and Michigan also experimented with the
'splake', a hybrid of the native lake trout and brook (or
speckled) trout. None of these predators has been able to
reproduce very well if at all, so the fishery has been maintained
by stocking year after year. Ironically, the exception is the
pink salmon, a small species accidentally introduced to Lake
Superior in 1955, that survived to establish spawning
populations. They spread through lakes Michigan and Huron, where
they established self-propagating populations by the 1980s.
RECREATION
Since early in the industrial age, the waterways, shorelines
and woodlands of the Great lakes region have been attractions for
leisure time activities. Many of the utilitarian activities that
were so important in the early settlement and industrial
development became recreational activities in later years. For
example, boating, fishing, and canoeing were once commercial
activities, but are now primarily leisure pursuits.
Recreation in the area became an important economic and
social activity with the age of travel in the 19th century. A
thriving pleasure-boat industry based on the newly constructed
canals developed, bringing people into the region in conjunction
with rail and road travel. Niagara Falls attracted travellers
from considerable distances and was one of the first stimulants
to the growth of a leisure-related economy. Later, the
reputation of the lower lakes region as the frontier of a
pristine wilderness drew people seeking restful cures and miracle
waters to the many spas and 'clinics' which developed along the
waterway.
In the 20th century, more people had more free time. With
industrial growth, greater personal disposable income and shorter
work weeks, people of all walks of life began to spend their
leisure time beyond the city limits. Governments on both sides
of the border acquired lands and began to develop an extensive
system of parks, wilderness areas and conservation areas in order
to protect valuable local resources and to serve the needs of the
population for recreation areas. Unfortunately, by the time the
need for publicly accessible recreation lands had become
apparent, much of the land in the basin, including virtually all
the shoreline on the lower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
eas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
ower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
.'+ +F
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Fish were important as food for the region's native people, as well as for the first European settlers. Commercial fishing began about 1820 and expanded about 20 percent per year. The largest Great Lakes fish harvests were recorded in 1889 and 1899 at some 67,000 tonnes (147 million pounds). However, by the 1880s some preferred species in Lake Erie had declined. Catches increased with more efficient fishing equipment but the golden days of the commercial fishery were over by the late 1950s. Since then, average annual catches have been around 50,000 tonnes (110 million pounds). The value of the commercial fishery has declined drastically because the more valuable, larger fish have given way to small and relatively low-value species. Over-fishing, pollution, shoreline and stream habitat destruction, and accidental and deliberate introduction of exotic species such as the sea lamprey all played a part in the decline of the fishery.................
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Sport Fishery
Several factors have contributed to the success of the sport fisheries. The sea lamprey, which almost destroyed the lake trout population, is being successfully controlled using chemical lampricides and low-head barrier dams. Walleye populations rebounded in Lake Erie owing to regulation of the commercial fishery and improvements in water quality. The population of
alewife exploded as lamprey destroyed native top predators. The increase in alewife provided a forage base for new predators such as coho and chinook salmon, which were introduced in the 1960s to fill the gap left by depleted lake trout stocks, when lamprey populations declined.
The sport fishery developed quickly as Pacific salmon rapidly grew to large sizes after they were introduced into Lake Michigan. Charter fleets developed and a minor tourist boom led to plans to develop a large fish stocking program to fuel a new sport fishing industry.
By 1980, the idea of stocking exotic fish such as salmon to support the sport fishery had spread to all the lakes and jurisdictions. Ontario and Michigan also experimented with the
splake
, a hybrid of the native lake trout and brook (or speckled) trout. None of these predators has been able to reproduce very well, if at all, so the fishery has been maintained by stocking year after year. Ironically, the exception is the pink salmon, a small species accidentally introduced into Lake Superior in 1955. It has survived to establish spawning populations and spread through Lakes Michigan and Huron, where it established self-propagating populations by the 1980s.
the 1980s.
y the
1980s.
and woodlands of the Great lakes region have been attractions for
leisure time activities. Many of the utilitarian activities that
were so important in the early settlement and industrial
development became recreational activities in later years. For
example, boating, fishing, and canoeing were once commercial
activities, but are now primarily leisure pursuits.
Recreation in the area became an important economic and
social activity with the age of travel in the 19th century. A
thriving pleasure-boat industry based on the newly constructed
canals developed, bringing people into the region in conjunction
with rail and road travel. Niagara Falls attracted travellers
from considerable distances and was one of the first stimulants
to the growth of a leisure-related economy. Later, the
reputation of the lower lakes region as the frontier of a
pristine wilderness drew people seeking restful cures and miracle
waters to the many spas and 'clinics' which developed along the
waterway.
In the 20th century, more people had more free time. With
industrial growth, greater personal disposable income and shorter
work weeks, people of all walks of life began to spend their
leisure time beyond the city limits. Governments on both sides
of the border acquired lands and began to develop an extensive
system of parks, wilderness areas and conservation areas in order
to protect valuable local resources and to serve the needs of the
population for recreation areas. Unfortunately, by the time the
need for publicly accessible recreation lands had become
apparent, much of the land in the basin, including virtually all
the shoreline on the lower lakes, was in private hands. Today,
about 80 percent of the U.S. shoreline and 20 percent of the
Canadian shore is privately owned and not accessible to the
public.
The recreation industry includes production and sale of
sports equipment and boats , marinas, resorts, restaurants and
related service industries that cater to a wide range of
recreational activities. In some areas of the Basin, recreation
and tourism is becoming an increasingly important component of
the economy in place of manufacturing. The Great Lakes Basin
provides a wide range of recreational opportunities ranging from
pristine wilderness activities as found in national parks such as
Isle Royale and Pukaskwa, to intensive urban waterfront beaches
in major urban areas.
The increasingly intensive recreational development of the
Great Lakes has had mixed impacts. Some recreational activities
cause environmental damage. Extensive development of cottage
areas, summer home sites, beaches and marinas has resulted loss
of wetland dune and forest areas. Shoreline alteration by
developers and individual property owners have caused change in
the shoreline erosion and deposition process, often to the
detriment of important beach and wetland systems that depend on
upon these processes. The development of areas susceptible to
flooding and erosion has caused considerable public pressure to
manage lake levels to prevent changes which are part of natural
weather patterns and processes. Pollution from recreational
sites and boats has also caused water quality degradation.
Recreational uses are a threat to the quality of the Great Lakes
ecosystem, but also provide a basis for protecting quality by
attracting and involving people who recognize that protection of
the ecosystem is essential to sustain the recreation that they
value. People who use the water for its fun and beauty can
become a potent force in the protection of the ecosystem.
Naturalists, anglers and cottagers were among the first to bring
environmental issues to the attention of the public and call for
the cleanup of the lakes in the 1950s and 1960s when
eutrophication threatened favored fishing, bathing and wildlife
sites. Today more people than ever use and value the lakes for
recreational purposes.
Recent years have seen a major resurgence in recreational
fishing as the walleye fisheries recover and the new salmon
fisheries develop. Lake Ontario now sports a very important
salmon and trout recreational fishery. The water quality recovery
in Lake Erie has been complemented by record walleye reproduction
in recent years. In many areas, Buffalo, Cleveland, Chicago and
Toronto particularly, there has been urban renewal movements with
the lake front as a primary focus. Developing public access to
the water is a key element of these renewal projects.
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URBANIZATION AND INDUSTRIAL GROWTH
Nearly all the settlements that grew into cities in the Great Lakes region were established on the waterways that transported people, raw materials and goods. The largest urban areas developed at the mouths of tributaries because of transportation advantages and the apparently inexhaustible supply of fresh water for domestic and industrial use. Historically, the major industries in the Great Lakes region have produced steel, paper, chemicals, automobiles and other manufactured goods.
A large part of the steel industry in Canada and the United States is concentrated in the Great Lakes because iron ore, coal and limestone can be carried on the lakes from mines and quarries to steel mills. In the United States, ore is carried from mines near Lake Superior to steel mills at the south end of Lake Michigan and at Detroit, Cleveland, and Lorain in the Lake Erie basin. In Canada, ore from the upper lakes region is processed in steel mills at Sault Ste. Marie, Hamilton and Nanticoke.
Paper-making in the U.S. occurs primarily on the upper lakes, with the largest concentration of mills along the Fox River, which feeds into Green Bay on Lake Michigan. In Canada, mills are located along the Welland Canal as well as along the upper lakes. Chemical industries developed on both sides of the Niagara River because of the availability of cheap electricity. Other major concentrations of chemical production are located near Saginaw Bay in Lake Huron and in Sarnia, Ontario, on the St. Clair River, because of abundant salt deposits and plentiful water.
All of these industrial activities produce vast quantities of wastes. Initially the wastes of urban-industrial centres did not appear to pose serious problems. Throughout most of the 19th century industrial wastes were dumped into the waterways, diluted and dispersed. Eventually, problems emerged when municipal water supplies became contaminated with urban-industrial effluent. The threat to public health from disease organisms prompted some cities to adopt practices that seemed for the time to solve the problem.
In 1854, Chicago experienced a cholera epidemic in which 5 percent of the population perished, and in 1891, the rate of death due to typhoid fever had reached a high of 124 per 100,000 population. To protect its drinking water supply from sewage, Chicago reversed the flow of the Chicago River away from Lake Michigan. A diversion channel was dug to carry sewage effluent away from Lake Michigan into the Illinois and Mississippi River system. In Hamilton, in the 1870s, water could no longer be drawn from the harbour or from local wells because of contamination. A steam-powered water pump
was installed to draw deep water from Lake Ontario for distribution
throughout the city.
Many of the dangers of industrial pollution to the Great Lakes and to human and environmental health were not recognized until recently, in part because their presence and their effects are difficult to detect. In recent years this has become especially evident where aging industrial disposal sites leak chemicals discarded many years ago into the environment or where sediments contaminated by long-standing industrial activities continue to contribute dangerous pollutants to the waterways. Now the region must cope with cleanup of the pollution from these past activities at the same time that the industrial base for the regional economy is struggling to remain competitive.
Use of Great Lakes resources brought wealth and well-being to the residents of Great Lakes cities but the full price of the concentration of industry and people is only now being understood. The cleanup of the Great Lakes region will require continuous expenditure by, and cooperation among, state, provincial and federal agencies, local governments and industry. Through this cooperation, combined with public involvement, contaminant levels in the Great Lakes ecosystem have declined dramatically since the 1970s. Because many pollutants tend to persist in the environment, levels must continue to be reduced. Pollution-prevention measures are being combined with cleanup to deal with pollution in the Great Lakes. eat Lakes. at Lakes. lution in the Great
Lakes. eat Lakes.
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In 1854, Chicago experienced a cholera epidemic in which 5 percent of the population perished, and in 1891, the rate of death due to typhoid fever had reached a high of 124 per 100,000 population. To protect its drinking water supply from sewage, Chicago reversed the flow of the Chicago River away from Lake Michigan. A diversion channel was dug to carry sewage effluent away from Lake Michigan into the Illinois and Mississippi River system. In Hamilton, in the 1870s, water could no longer be drawn from the harbour or from local wells because of contamination. A steam-powered water pump
was installed to draw deep water from Lake Ontario for distribution throughout the city..
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Water Levels and Diversions
The responsibilities of the International Joint Commission (IJC) for levels and flows of the Great Lakes are separate from its responsibilities for water quality. Water quality objectives are set by the Great Lakes Water Quality Agreement, but decisions about levels and flows are made to comply with the terms of the l909 Boundary Waters Treaty.
Only limited controls of levels and flows are possible and only for Lake Superior and Lake Ontario. The flows are controlled by locks and dams on the St. Marys River, at Niagara Falls and in the St. Lawrence. Special boards of experts advise the IJC about meeting the terms of the treaty. Members of the binational control boards are equally divided between government agencies in both countries. Until l973, the IJC managed levels and flows for navigation and hydropower production purposes. Since then, the IJC has tried to balance these interests with prevention of shore erosion.
At present, water is diverted into the Great Lakes system from the Hudson Bay watershed through Long Lac and Lake Ogoki, and diverted out of the Great Lakes and into the Mississippi watershed at Chicago. These diversions are almost equally balanced and have had little long-term effect on levels of the lakes.
2, the IJC reported on a study of the effects of existing
diversions into and out of the Great Lakes system and on
consumptive uses. Until this study, consumptive use had not been
considered significant for the Great Lakes because the volume of
water in the system is so large. The study concluded that climate
and weather changes affect levels of the lakes far more than
existing human-made diversions. However, the report concluded that
if consumptive uses of water continue to increase at historical
rates, outflows through the St. Lawrence River could be reduced by
as much as 8 percent by around the year 2030.
As illustrated by the hydrograph shown in Chapter two, lake levels
vary from year to year and can be expected to continue to do so.
Following the period of high lake levels in the 1980s, the IJC
conducted another study of levels and the feasibility of modifying
them through various means. In 1993, the study concluded that the
costs of major engineering works to further regulate the levels and
flows of the Great Lakes and St. Lawrence River would exceed the
benefits provided and would have negative environmental impacts.
Instead, it recommended comprehensive and coordinated land-use and
shoreline management programs throughout the basin that would help
reduce vulnerability to flood and erosion damages.....d that climate
and weather changes affect levels of the lakes far more than
existing human-made diversions. However, the report concluded that
if consumptive uses of water continue to increase at historical
rates, outflows through the St. Lawrence River could be reduced by
as much as 8 percent by around the year 2030.
As illustrated by the hydrograph shown in Chapter two, lake levels
vary from year to year and can be expected to continue to do so.
Following the period of high lake levels in the 1980s, the IJC
conducted another study of levels and the feasibility of modifying
them through various means. In 1993, the study concluded that the
costs of major engineering works to further regulate the levels and
flows of the Great Lakes and St. Lawrence River would exceed the
benefits provided and would have negative environmental impacts.
Instead, it recommended comprehensive and coordinated land-use and
shoreline management programs throughout the basin that would help
reduce vulnerability to flood and erosion damages..............................
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Pathogens
Historically, the primary reason for water pollution control was prevention of waterborne disease. Municipalities began treating drinking water by adding chlorine, as a disinfectant. This proved to be a simple solution to a very serious public health problem, throughout the water distribution system. Chlorine is still used because it is able to kill pathogens throughout the distribution system.
Humans can acquire bacterial, viral and parasitic diseases through direct body contact with contaminated water as well as by drinking the water. Preventing disease transmission of this kind usually means closing affected beaches during the summer when the water is warm and when bacteria from human and animal faeces reach higher concentrations. This is usually attributed to the common practice of combining storm and sanitary sewers in urban areas. Although this practice has been discontinued, existing combined sewers contribute to contamination problems during periods of high rainfall and urban runoff. At these times, sewage collection and treatment systems cannot handle the large volumes of combined storm and sanitary flow. The result is that untreated sewage, diluted by urban runoff, is discharged directly into waterways.
Remedial action can be very costly if the preferred solution is replacement of the combined sewers in urban areas with separate storm and sanitary sewers. However, alternative techniques such as combined sewer overflow retention for later treatment can be used, greatly reducing the problem at lower costs than sewer separation. Beach closures have become more infrequent with improved treatment of sewage effluent................................e effluent.e become more
infrequent with improved treatment of sewage effluent.
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Eutrophication and Oxygen Depletion
Lakes can be characterized by their biological productivity, that is, the amount of living material supported within them, primarily in the form of algae. The least productive lakes are called oligotrophic; those with intermediate productivity are mesotrophic; and the most productive are eutrophic. The variables that determine productivity are temperature, light,
depth and volume, and the amount of nutrients received from the environment.
Except in shallow bays and shoreline marshes, the Great Lakes were oligotrophic before European settlements and industrialization. Their size, depth and the climate kept them continuously cool and clear. The lakes received small amounts of fertilizers such as phosphorus and nitrogen from decomposing organic material in runoff from forested lands. Small amounts of nitrogen and phosphorus also came from the atmosphere.
These conditions have changed. Temperatures of many tributaries have been increased by removal of vegetative shade cover and some by thermal pollution. But, more importantly, the amount of nutrients and organic material entering the lakes has increased with intensified urbanization and agriculture. Nutrient loading increased with the advent of phosphate detergents and inorganic fertilizers. Although controlled in most jurisdictions bordering the Great Lakes, phosphates in detergents continue to be a problem where they are not regulated.
Increased nutrients in the lakes stimulate the growth of green plants including algae. The amount of plant growth increases rapidly in the same way that applying lawn fertilizers (nitrogen, phosphorus and potassium) results in rapid, green growth. In the aquatic system the increased plant life eventually dies, settles to the bottom and decomposes. During decomposition, the organisms which break down the plants use up oxygen dissolved in the water near the bottom. With more growth there is more material to be decomposed, and more consumption of oxygen. Under normal conditions, when nutrient loadings are low, dissolved oxygen levels are maintained by the diffusion of oxygen into water, mixing by currents and wave action, and by the oxygen production of photosynthesizing plants.
Depletion of oxygen through decomposition of organic material is known as biochemical oxygen demand (BOD) which is generated from two different sources. In tributaries and harbours it is often caused by materials contained in the discharges from treatment plants. The other principal source is decaying algae. In large embayments and open lake areas such as the central basin of Lake Erie, algal BOD is the primary problem.
As the BOD load increases and as oxygen levels drop, certain species of fish can be killed and pollution-tolerant species that require less oxygen such as sludge worms and carp replace the original species. Changes in species of algae, bottom-dwelling organisms (or benthos), and fish are therefore good biological indicators of oxygen depletion. Turbidity in the water as well as an increase in chlorophyll also accompany accelerated algal growth and indicate increased eutrophication.
Lake Erie was the first of the Great Lakes to demonstrate a serious problem of eutrophication because it is the shallowest, warmest and naturally most productive. Lake Erie also experienced early and intense development of its lands for agricultural and urban uses. About one-third of the total Great Lakes basin population lives within its drainage area and surpasses all other lakes in the receipt of effluent from sewage treatment plants.
Oxygen depletion in the shallow central basin of Lake Erie was first reported in the late 1920s. Studies showed that the area of oxygen depletion grew larger with time, although the extent varied from year to year due, at least in part, to weather conditions. Eutrophication was believed to be the primary cause. Before controls could be developed, it was necessary to determine which nutrients were most important in causing eutrophication in previously mesotrophic or oligotrophic waters. By the late 1960s, the scientific consensus was that phosphorus was the key nutrient in the Great Lakes and that controlling the input of phosphorus could reduce eutrophication.
The central basin of Lake Erie is especially susceptible to depletion of oxygen in waters near the bottom because it stratifies in summer, forming a relatively thin layer of cool water, the hypolimnion, which is isolated from oxygen-rich surface waters. Oxygen is rapidly depleted from this thin layer as a result of decomposition of organic matter. When dissolved oxygen levels reach zero, the waters are considered to be anoxic. With anoxia, many chemical processes change and previously oxidized pollutants may be altered to forms that are more readily available for uptake by the water. By contrast, the western basin of the lake is not generally susceptible to anoxia because the wind keeps the shallow basin well mixed, preventing complete stratification. The eastern basin is deeper and the thick
hypolimnion contains enough oxygen to prevent anoxia.
In both Canada and the United States, the belief that Lake Erie was 'dying' increased public alarm about water pollution everywhere. Even the casual observer could see that the lake was in trouble. Cladophora, a filamentous alga which thrives under eutrophic conditions, became the dominant nearshore species covering beaches in green, slimy, rotting masses. Increased turbidity caused the lake to appear greenish-brown and murky.
In response to public concern, new pollution control laws were adopted in both countries to deal with water quality problems including phosphorus loadings to the lakes. In 1972, Canada and the United States signed the Great Lakes Water Quality Agreement to begin a binational Great Lakes cleanup that emphasized the reduction of phosphorus entering the lakes.
Studies were conducted to determine the maximum concentrations
of phosphorus that could be tolerated by the Lakes without producing nuisance conditions or disturbing the integrity of the aquatic community. Mathematical models were then developed to predict the maximum annual loads of phosphorus that could be assimilated by the Lakes without exceeding the desired phosphorus concentrations. These maximum amounts were then included in the Great Lakes Water Quality Agreement. Following a 1983 review of progress made through waste treatment and detergent phosphate controls, it was determined that control of phosphorus from land runoff was also necessary. Ten years later a high degree of control of point sources had been attained through regulation, and it was clear that target levels could be met through additional progress in voluntary control of nonpoint sources.
The control of phosphorus and associated eutrophication in the Great Lakes represents an unprecedented success in producing environmental results through international cooperation.
Phosphorus loads entering the lakes have been reduced to below the maximum amounts specified in the Agreement for Lakes Superior, Huron and Michigan and are at or near maximum amounts for Lakes Erie and Ontario. Phosphorus concentrations in the Lakes are similarly below maximum levels in the upper lakes and at or near maximum concentrations in Lakes Ontario and Erie. In the shallow western basin of Lake Erie, concentrations are close to being within maximum levels during calm periods, but are highly variable due to weather and resuspension of sediments.
The return to lower amounts of phosphorus has not only resulted in reducing excess growth of algae, but has also changed the composition of the algal population. Nuisance algal species have given way to more desirable and historically prevalent species, such as diatoms, thereby eliminating nuisance conditions and improving the quality of the food chain for other organisms.
her organisms.
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Most of the early Canadian settlements in the Great Lakes basin were located on embayments or at the mouths of streams and local waterways were used to dispose of household wastes and sewage. These wastes contributed large quantities of plant nutrients (phosphorus and nitrogen) and organic matter to local waterbodies. The warm, nutrient-rich waters promoted algal growth, reduced water clarity, altered the abundance of rooted aquatic plants sensitive to light, and reduced the abundance of fish associated with weed beds such as Largemouth Bass and Northern Pike.
Degradation of the organic wastes and algal mats depleted the waters of dissolved oxygen so that only organisms tolerant of low oxygen levels were able to survive in urban embayments. This sequence of events, beginning with an increase in the fertility of aquatic systems, is referred to as cultural eutrophication. In the Great Lakes, the lower lakes (Erie and Ontario) were
naturally more fertile than the other lakes......................................
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Population growth in the 20th Century marked the beginning of cultural
eutrophication processes throughout the Great Lakes. In the first half of
the century eutrophication was probably occurring but was not widely perceived
because the phenomenon was localized to urban embayments. The rapid
population growth after WW II, particularly the urban population in the lower
part of the Great Lakes basin, lead to large scale eutrophication processes
which affected the lakes as a whole. By the 1960s there were numerous
reports that Lake Erie was "dying". Blue-green algae blooms in the offshore
waters were a nuisance, turning the water green and affecting the taste of
drinking water supplies. Large mats of rotting Cladophora, a large
filamentous green algae, covered the beaches and nearshore spawning shoals
vital to fish stocks. Decomposition of dead algae in the offshore waters of the central basin of Lake Erie depleted the oxygen in these waters and led to reductions in the abundance of sensitive aquatic organisms such as Mayflies and Lake Trout.
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There is evidence for the restoration of the lower Great Lakes as a
result of actions toreduce their fertility over the past 25 years. The lower
lakes are tending towards oligotrophic conditions, at least in the offshore
waters. Massive algal blooms no longer occur in the offshore waters of Lake
Erie and Cladophora rarely fouls the beaches or spawning shoals of Lakes Erie
and Ontario anymore. Cultural eutrophication continues to be a problem in
many embayments on all of the Great Lakes, with 23 of 43 reporting in 1994 that beneficial uses are still impaired by eutrophication or undesirable algae. The deepest waters of the central basin of Lake Erie occasionally experience anoxic (depleted oxygen) conditions during the summer, but the spatial and temporal
scope of these events is greatly reduced compared with episodes in the 1960s. However, there also is some evidence that brief periods of anoxia occurred in the central basin of Lake Erie prior to the onset of cultural eutrophication and some authorities suggest that based on this evidence, the goal of year-round oxygenation is not practicable. At present, this situation has not been
resolved scientifically. In the upper Great Lakes these efforts have
Although phosphorus loadings and concentrations in the Great Lakes have
declined and stabilized over the past 25 years, open-lake concentrations of
but remain well below 10 ppm, the guideline for the protection of drinking
water, in all of the lakes (Neilson et al. 1994). These opposing trends in
nutrient levels apparently influenced algal species composition, leading to
a shift from nitrogen-fixing blue-green algae species that dominated in the
1960s and 1970s and caused most of the nuisance blooms, towards more
desirable and historically dominant species of diatoms and green algae
(Makarewicz 1993). Atmospheric deposition is believed to be the major
source of nitrogen in the upper lakes while increased use of chemical
fertilizers and gaseous emissions of nitrogen compounds in the Lake Erie
basin appear to be responsible for nitrogen increases in the lower lakes
(Neilson et al. 1994).
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TOXIC CONTAMINANTS
Toxic contamination of the environment and the potential risk to human health have been the result of the increased production and widespread use of synthetic organic chemicals and metals since the 1940s. The dangers of toxic substances in the natural environment were first illustrated through the study of the effects, persistence and movement of the pesticide DDT.
Toxic pollutants include human-made organic chemicals and heavy metals that can be acutely toxic in relatively small amounts and injurious through long-term (chronic) exposure in minute concentrations. Many of the contaminants that are present in the environment have the potential to increase the risk of cancer, birth defects and genetic mutations through long-term, low-level exposure.
Many toxic substances tend to bioaccumulate as they pass up the food chain in the aquatic ecosystem. While the concentrations in water of chemicals such as PCBs may be so low that they are almost undetectable, biomagnification through the food chain can increase levels in predator fish such as large trout and salmon by a million times. Still further biomagnification occurs in birds and other animals that eat fish. There is little doubt that bioaccumulative toxic substances continue to affect aquatic organisms in the lakes and birds and animals that eat them. Public health and environmental agencies in the Great Lakes states and the Province
of Ontario warn against human consumption of certain fish. Some fish cannot be sold commercially because of high levels of PCBs, mercury or other substances.
Fish consumption provides the greatest potential for exposure of
humans to toxic substances found in the Great Lakes when compared
with other activities such as drinking tap water or swimming. For
example, a person who eats one meal of lake trout from Lake
Michigan will be exposed to more PCBs in one meal than in a
lifetime of drinking water from the lake.
People who consume a lot of fish and wildlife have greater exposure
to contaminants than those who do not. Higher exposure means
greater health risks, specific
at-risk
groups of concern include
native peoples, anglers and their families, and certain immigrant
groups who rely on fish and wildlife for a large part of their
diet. Epidemiological studies of Michigan residents have
demonstrated that people who regularly eat fish with high levels of
PCBs have much higher concentrations in their bodies than others.
The relationship between this exposure and effects on human health
is of concern.
Recent scientific evidence, based mostly on observations in
animals, has raised concerns that exposure to low levels of some
contaminants may cause subtle effects on reproduction, development
and other physiological parameters. Effects may go easily unnoticed
in the short term, but in the long term may lead to serious
cumulative damage. New studies in the Great Lakes basin and
throughout the world are now looking at effects of persistent
contaminants on the immune system, the nervous system, pre-natal
and post-natal development, fertility and the development of
cancers.
Disease rates within the Great Lakes basin are not significantly
different from those in other parts of the U.S. or Canada. However,
certain groups may be more sensitive to the effects of contaminant
exposure, including the developing fetus and child, the elderly and
people whose immune systems are already suppressed. Reporting for
some of these disease states is often poor, making population-wide
assessments very difficult.
Researchers at Wayne State University have been following from
birth a group of children born to mothers who had regularly eaten
at least 11.8 kg of contaminated Lake Michigan fish over a 6-year
period. The study linked exposure to PCBs to decreases in birth
weight, head circumference and gestational age of the new-born
infants. Follow-ups of the children have documented subtle deficits
in short-term memory and certain cognitive skills. The extent to
which these deficits are a result of contaminant exposures is still
a subject of great debate, prompting other researchers to conduct
similar studies in human subjects and laboratory studies with rats.
Concentrations of PCBs and other toxic contaminants in Great Lakes
fish have declined significantly since the exposure of the mothers
in the study took place. Contaminants in breast milk have also
declined. Despite this progress, contaminant levels in fish still
remain high enough to require fish consumption advisories for some
species and sizes of fish. The advisories are strictest for
pregnant women and pre-teen children, to minimize exposures and
protect health.
Some of the chemicals found in the lakes have been shown to be
cancer-causing agents (carcinogens) in high-dose animal studies.
The identification of a chemical as a human carcinogen is often
difficult, since many years may elapse between the original
exposure to the chemical and development of the cancer. Other
external factors can contribute to the same cancer (for example,
smoking is a common confounder in research studies) and complicate
our certainty about the role played by a particular chemical. There
is also concern that interactions between substances can interfere
with (by antagonism) or enhance (by synergism) the action of
another individual chemical.
There is emerging public concern over certain contaminants that
mimic hormones in the human body, with the potential effect of
altering sexual characteristics and other hormonal functions. DDT,
one of several chlorinated organic compounds that can weakly mimic
oestrogen, is under investigation for potential linkages to one
type of breast cancer. As well, studies are examining the potential
of TCDD, a form of dioxin, to mimic oestrogen, with the potential
results of feminization of sex organs in males and disruption in
the development of other sexual characteristics. There are also
questions about the effects of oestrogen-like compounds on sperm
quality.
Research is continuing to quantify what the actual exposures to
Great Lakes toxic contaminants are for various at-risk groups and
the general population, and the relationship between exposure and
health outcomes. In the meantime, measures must continue to be
taken to minimize exposure, to protect health. This will certainly
occur through public education and lifestyle changes to avoid
exposures. However, cleanup and pollution prevention are the
long-term real solutions to reducing human exposure and protecting
and promoting good health.
Table:
Dredging
Shipping
Storms
Biotic Disturbanceeeeeees
Biotic Disturbance
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Fish consumption provides the greatest potential for exposure of humans to toxic substances found in the Great Lakes when compared with other activities such as drinking tap water or swimming. For example, a person who eats one meal of lake trout from Lake Michigan will be exposed to more PCBs in one meal than in a lifetime of drinking water from the lake.
People who consume a lot of fish and wildlife have greater exposure to contaminants than those who do not. Higher exposure means greater health risks, specific
at-risk
groups of concern include native peoples, anglers and their families, and certain immigrant groups who rely on fish and wildlife for a large part of their diet. Epidemiological studies of Michigan residents have demonstrated that people who regularly eat fish with high levels of PCBs have much higher concentrations in their bodies than others. The relationship between this exposure and effects on human health is of concern.
Recent scientific evidence, based mostly on observations in animals, has raised concerns that exposure to low levels of some contaminants may cause subtle effects on reproduction, development and other physiological parameters. Effects may go easily unnoticed in the short term, but in the long term may lead to serious cumulative damage. New studies in the Great Lakes basin and throughout the world are now looking at effects of persistent contaminants on the immune system, the nervous system, pre-natal and post-natal development, fertility and the development of
cancers.
Disease rates within the Great Lakes basin are not significantly different from those in other parts of the U.S. or Canada. However, certain groups may be more sensitive to the effects of contaminant exposure, including the developing fetus and child, the elderly and people whose immune systems are already suppressed. Reporting for some of these disease states is often poor, making population-wide assessments very difficult.
Researchers at Wayne State University have been following from birth a group of children born to mothers who had regularly eaten at least 11.8 kg of contaminated Lake Michigan fish over a 6-year period. The study linked exposure to PCBs to decreases in birth weight, head circumference and gestational age of the new-born infants. Follow-ups of the children have documented subtle deficits in short-term memory and certain cognitive skills. The extent to which these deficits are a result of contaminant exposures is still a subject of great debate, prompting other researchers to conduct similar studies in human subjects and laboratory studies with rats.
Concentrations of PCBs and other toxic contaminants in Great Lakes fish have declined significantly since the exposure of the mothers in the study took place. Contaminants in breast milk have also declined. Despite this progress, contaminant levels in fish still remain high enough to require fish consumption advisories for some species and sizes of fish. The advisories are strictest for pregnant women and pre-teen children, to minimize exposures and protect health.
Some of the chemicals found in the lakes have been shown to be cancer-causing agents (carcinogens) in high-dose animal studies. The identification of a chemical as a human carcinogen is often difficult, since many years may elapse between the original exposure to the chemical and development of the cancer. Other external factors can contribute to the same cancer (for example, smoking is a common confounder in research studies) and complicate our certainty about the role played by a particular chemical. There is also concern that interactions between substances can interfere with (by antagonism) or enhance (by synergism) the action of another individual chemical.
There is emerging public concern over certain contaminants that mimic hormones in the human body, with the potential effect of altering sexual characteristics and other hormonal functions. DDT, one of several chlorinated organic compounds that can weakly mimic oestrogen, is under investigation for potential linkages to one type of breast cancer. As well, studies are examining the potential of TCDD, a form of dioxin, to mimic oestrogen, with the potential results of feminization of sex organs in males and disruption in the development of other sexual characteristics. There are also questions about the effects of oestrogen-like compounds on sperm
quality.
Research is continuing to quantify what the actual exposures to Great Lakes toxic contaminants are for various at-risk groups and the general population, and the relationship between exposure and health outcomes. In the meantime, measures must continue to be taken to minimize exposure, to protect health. This will certainly occur through public education and lifestyle changes to avoid exposures. However, cleanup and pollution prevention are the long-term real solutions to reducing human exposure and protecting and promoting good health.........
Table:
Dredging
Shipping
Storms
Biotic Disturbanceeeo the same cancer (for example,
smoking is a common confounder in research studies) and complicate
our certainty about the role played by a particular chemical. There
is also concern that interactions between substances can interfere
with (by antagonism) or enhance (by synergism) the action of
another individual chemical.
There is emerging public concern over certain contaminants that
mimic hormones in the human body, with the potential effect of
altering sexual characteristics and other hormonal functions. DDT,
one of several chlorinated organic compounds that can weakly mimic
oestrogen, is under investigation for potential linkages to one
type of breast cancer. As well, studies are examining the potential
of TCDD, a form of dioxin, to mimic oestrogen, with the potential
results of feminization of sex organs in males and disruption in
the development of other sexual characteristics. There are also
questions about the effects of oestrogen-like compounds on sperm
quality.
Research is continuing to quantify what the actual exposures to
Great Lakes toxic contaminants are for various at-risk groups and
the general population, and the relationship between exposure and
health outcomes. In the meantime, measures must continue to be
taken to minimize exposure, to protect health. This will certainly
occur through public education and lifestyle changes to avoid
exposures. However, cleanup and pollution prevention are the
long-term real solutions to reducing human exposure and protecting
and promoting good health.
Table:
Dredging
Shipping
Storms
Biotic Disturbanceeeeeees
Biotic Disturbance
linds slow
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atlas028
Pathways Of Pollution
Sediments that were contaminated before pollutant discharges were regulated are another source of pollution. Such in-place pollutants are a problem in most urban-industrial areas. Release of pollutants from sediments is believed to be occurring in connecting channels such as the Niagara, St. Clair and St. Marys Rivers, in harbours such as Hamilton, Toronto and the Grand Calumet, and in tributaries such as the Buffalo, Ashtabula and Black Rivers. Even where it is possible to remove highly contaminated sediments from harbours, removal can cause problems when sediments are placed in landfills that may later leak and contaminate wetlands and groundwater. Dredging for navigation can also present problems of disposal of dredge spoils. Disposal of highly polluted sediments in the open lakes has been prohibited since the 1960s. In both the U.S. and Canada, research and demonstration projects are being conducted to find effective ways to isolate, remove and destroy contaminated sediments.
Groundwater movement is another pathway for pollutants. As water
slowly passes through the ground it can pick up dissolved materials
that have been buried or soaked into the ground. Contamination of
groundwater tends to be localized near badly contaminated sites,
but it can also be wide- spread if the pollutant was used as a
pesticide. Because treatment of groundwater is very difficult and
expensive, prevention is clearly the best approach.
Surface runoff is the pathway for a wide variety of substances that
enter the lakes. Nutrients, pesticides and soils are released by
agricultural activities. In urban areas, street runoff includes
automobile-related substances such as salt, sand, asbestos,
cadmium, lead, oils and greases. Surface runoff also includes a
wide number of materials deposited with precipitation, which may
include particulates, bacteria, nutrients and toxic substances.
in harbours
such as Hamilton, Toronto and the Grand Calumet, and in tributaries
such as the Buffalo, Ashtabula and Black Rivers. Even where it is
possible to remove highly contaminated sediments from harbours,
removal can cause problems when sediments are placed in landfills
that may later leak and contaminate wetlands and groundwater.
Dredging for navigation can also present problems of disposal of
dredge spoils. Disposal of highly polluted sediments in the open
lakes has been prohibited since the 1960s. In both the U.S. and
Canada, research and demonstration projects are being conducted to
find effective ways to isolate, remove and destroy contaminated
sediments.
Groundwater movement is another pathway for pollutants. As water
slowly passes through the ground it can pick up dissolved materials
that have been buried or soaked into the ground. Contamination of
groundwater tends to be localized near badly contaminated sites,
but it can also be wide- spread if the pollutant was used as a
pesticide. Because treatment of groundwater is very difficult and
expensive, prevention is clearly the best approach.
Surface runoff is the pathway for a wide variety of substances that
enter the lakes. Nutrients, pesticides and soils are released by
agricultural activities. In urban areas, street runoff includes
automobile-related substances such as salt, sand, asbestos,
cadmium, lead, oils and greases. Surface runoff also includes a
wide number of materials deposited with precipitation, which may
include particulates, bacteria, nutrients and toxic substances.
d toxic substances.
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atlas016
field 1
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Habitat and Biodiversity
Habitat within the Great Lakes Basin has been significantly altered following the arrival of European settlers, especially during the last 150 years. Nearly all of the existing forests have been cut at least once and the forest and prairie soils suited to agriculture have been plowed or intensively grazed. This, together with construction of dams and urbanization has created vast changes in the plant and animal populations. Streams have been changed not only by direct physical disturbance, but by sedimentation and changes in runoff rates due to changing land use and by increases in temperature caused by removal of shading vegetation.
Wetlands are a key category of habitat within the basin because of their importance to the aquatic plant and animal communities. Many natural wetlands have been filled in or drained for agriculture, urban uses, shoreline development, recreation and resource extraction (peat mining). Losses have been particularly high in the southern portions of the Basin. It is estimated, for example, that between 70 and 80 percent of the original wetlands of Southern Ontario have been lost since European settlement, and losses in the U.S. portion of the basin range from 42% in Minnesota to 92% in Ohio. Unfortunately, some governments continue to encourage this practice through drainage subsidies to farmers. The loss of these lands poses special problems for hydrological processes and water quality because of the natural storage and cleansing functions of wetlands. Moreover, the loss makes difficult the preservation and protection of certain wildlife species that require wetlands for part or all of their life cycle.
(Biodiversity) refers to both the number of species and the genetic diversity within populations of each species. Some species have become extinct as a result of changes within the Great Lakes basin and many others are being threatened with extinction or loss of important genetic diversity. Recovery of some highly visible species such as eagles and cormorants has been dramatic, but other less known species remain in danger.
The loss of genetic diversity or variability within a species, is a less well understood problem. An example is the loss of genetic stocks of fish that instinctively spawn or feed in certain areas or under certain conditions. This is thought to be a factor in the lack of recovery of some species such as lake trout, which are apparently not able to sustain naturally reproducing populations except in Lake Superior. Even in Lake Superior all of the genetic strains of lake trout that once spawned in tributaries have been lost. Lack of diversity within a species can also increase the vulnerability of the population to catastrophic loss caused by disease or a major change in environmental conditions.
As many forms of pollution have been controlled and reduced, the importance of habitat is being recognized as critically important to the health of the Great Lakes ecosystem. As the physical, chemical and biological interactions of the ecosystem are becoming better understood, it has become apparent that no one component can be viewed in isolation. To protect any living component, its habitat and place within the system must be protected..
em must be
protected.
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Biodiversity (biological diversity) is the total variety of living
organisms (plants, animals, fungi, microbes) in the world or some particular part of the world and it includes all their individual variations (i.e., functional integrity of the Great Lakes ecosystem)..
. use it provides the information database for ecosystem self-organization. %
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Habitat within the Great Lakes Basin has been significantly altered following the arrival of European settlers, especially during the last 150 years. Nearly all of the existing forests have been cut at least once and the forest and prairie soils suited to agriculture have been plowed or intensively grazed. This, together with construction of dams and urbanization has created vast changes in the plant and animal populations. Streams have been changed not only by direct physical disturbance, but by sedimentation and changes in runoff rates due to changing land use and by increases in temperature caused by removal of shading vegetation.
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Wetlands are a key category of habitat within the basin because of their importance to the aquatic plant and animal communities. Many natural wetlands have been filled in or drained for agriculture, urban uses, shoreline development, recreation and resource extraction (peat mining). Losses have been particularly high in the southern portions of the Basin. It is estimated, for example, that between 70 and 80 percent of the original wetlands of Southern Ontario have been lost since European settlement, and losses in the U.S. portion of the basin range from 42% in Minnesota to 92% in Ohio. Unfortunately, some governments continue to encourage this practice through drainage subsidies to farmers. The loss of these lands poses special problems for hydrological processes and water quality because of the natural storage and cleansing functions of wetlands. Moreover, the loss makes difficult the preservation and protection of certain wildlife species that require wetlands for part or all of their life cycle.................
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(Biodiversity) refers to both the number of species and the genetic diversity within populations of each species. Some species have become extinct as a result of changes within the Great Lakes basin and many others are being threatened with extinction or loss of important genetic diversity. Recovery of some highly visible species such as eagles and cormorants has been dramatic, but other less known species remain in danger.
The loss of genetic diversity or variability within a species, is a less well understood problem. An example is the loss of genetic stocks of fish that instinctively spawn or feed in certain areas or under certain conditions. This is thought to be a factor in the lack of recovery of some species such as lake trout, which are apparently not able to sustain naturally reproducing populations except in Lake Superior. Even in Lake Superior all of the genetic strains of lake trout that once spawned in tributaries have been lost. Lack of diversity within a species can also increase the vulnerability of the population to catastrophic loss caused by disease or a major change in environmental conditions.
As many forms of pollution have been controlled and reduced, the importance of habitat is being recognized as critically important to the health of the Great Lakes ecosystem. As the physical, chemical and biological interactions of the ecosystem are becoming better understood, it has become apparent that no one component can be viewed in isolation. To protect any living component, its habitat and place within the system must be protected.
protected.
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atlas018
ecies
Exotic Species
An important cause of ecological change in the Great Lakes has been the introduction of exotic, i.e., non-native, species of plants and animals. In the lakes, sea lamprey, carp, smelt, alewife, Pacific salmon and zebra mussels, to name just a few, have had highly visible impacts. The effects of hundreds of other invading organisms are less obvious, but can be profound. On land, invading plants such as purple loosestrife and European buckthorn continue to displace native species. In some areas, major changes in terrestrial plant communities have been caused by suppression of fire. All of these disturbances have resulted in changes in aquatic and terrestrial habitat , causing further changes in plant and animal populations. The collective result has been the disruption of the complex communities of plants and animals that had evolved during thousands of years of presettlement conditions. Destruction of these complex communities by changes in land use or by invasion by exotic species has resulted in loss of biodiversity................
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atlas019
c areas of concern
Geographic Areas Of Concern
Overall, water quality in the lakes is improving due to the progress that has been made in controlling direct discharges of wastes from municipalities and industries under environmental laws adopted since the 1960s. Even so, some areas still suffer serious impairment of beneficial uses (drinking, fishing, swimming, etc.) and fail to meet environmental standards and objectives.
Serious problems remain throughout the basin in locations identified as Areas of Concern. Areas of Concern are those geographic areas where beneficial use of water or biota is adversely affected or where environmental criteria are exceeded to the extent that use impairment exists or is likely to exist. The purpose of establishing Areas of Concern is to encourage jurisdictions to form partnerships with local stakeholders to rehabilitate these acute, localized problem areas and to restore their beneficial uses. In these areas, existing routine programs are not expected to be sufficient to restore ecosystem quality to acceptable levels and special efforts are needed. Jurisdictions are implementing Remedial Action Plans (RAPs) to guide specific rehabilitation activities in all 42 areas. In one Area of Concern, Collingwood Harbour, benefical uses have been restored.
Most IJC Areas of Concern are near the mouths of tributaries where cities and industries are located. Several of the areas are along the connecting channels between the lakes. Pollutants are concentrated in these areas because of long-term accumulation of contaminants deposited from local point and nonpoint sources and from upstream sources. Nearly all the Areas of Concern have contaminated sediments.
Over the last decade, the nature of the problems associated with some areas has changed. For instance, as progress was made in restoring dissolved oxygen and reducing some toxic substances such as lead and mercury, it became apparent that the problem of dissolved oxygen had been obscuring other problems of toxic contamination. In these areas, continued remedial and preventive action is necessary.
RAPs are unique in their emphasis on multi-disciplinary, multi-agency, multi-stakeholder partnerships. By developing a locally based consensus on environmental problems, their causes and the key steps needed to solve them, RAPs provide a clear basis for action and accountability on the part of those responsible for taking action.
taking action.
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in concenra
Other Basin Concerns
Air pollution is often neglected when talking about water quality and health. Through long-range transport, persistent toxic contaminants are deposited in the Great Lakes. They then become available to living things through the food chain.
Acid precipitation created by continued use of fossil fuels in the transportation sector and in the production of electrical power, as well as from smelter emissions, may seriously affect the quality of aquatic ecosystems. Small lakes and tributaries that feed the Great Lakes are most susceptible. Because of the underlying sedimentary limestone in the lower Great Lakes, there is a natural capacity to buffer the effects of acid rain. However, concern remains for the lakes and tributaries originating in the northern forest on the Canadian Shield. In Ontario, Minnesota, Michigan and Wisconsin, acidification is already evident in many small lakes.
Smog has become a concern for people residing in the Great Lakes basin. Motor vehicle emissions concentrated in urban areas are a major contributor to the smog problem. Ground-level ozone is a major component of smog in the lower Great Lakes basin. Recent research has shown an increase in hospital admissions for respiratory illness on days when ground-level ozone and sulfate levels exceed guidelines.
The shoreline of the Great Lakes is under continual stress. In the lower lakes region little remains undeveloped. Most lakefront properties are in private ownership and thus under limited control by public authorities wishing to protect them. Erosion losses are high because of intensive development and loss of vegetative cover and other natural protection. Damages due to flooding are also of concern, particularly during periods of high lake levels. Flooding and erosion damages to private property lead to public pressure on governments to further regulate lake levels through diversion manipulation and control structures on outlet channels (see Chapter Three). The demand for public access to the lakes for recreation
has grown steadily in recent years and can be projected to continue. Currently, the greatest growth is in the development of marinas for recreational boating.
Some consideration has been given to the sale of water as a commodity to fast-growing water-poor areas such as the American Midwest and Southwest. These range from proposals for minor diversions out of the basin to mega-projects that would see large-scale alterations to the natural flows from as far away as James Bay, through the Great Lakes basin to the American sunbelt states. Opposition to such suggestions comes from environmentalists and others who fear the enormous consequences of such large-scale manipulation of the natural watersheds.
Climate change is a long-term threat to the Great Lakes ecosystem. If it caused lower lake levels, it would reduce shore erosion, but would, at a minimum, cause problems for navigation and wetlands. The ecosystem has survived changes in climate before, but global warming could occur in a far shorter time span, leaving insufficient time for plant species to adapt or move to favourable sites.
It would be a tragic irony if, because of our failure to deal with the pollution of the lakes and the effects of our development of the basin, we look out over the vast expanse of the lakes and realize that we have permanently damaged a sustaining natural resource...................................................ral
resource.
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lation
Box: Bioaccumulation And Biomagnification
The nutrients necessary for plant growth (e.g., nitrogen and phosphorus) are found at very low concentrations in most natural waters. In order to obtain sufficient quantities for growth, phytoplankton must collect these chemical elements from a relatively large volume of water.
In the process of collecting nutrients, they also collect certain human-made chemicals, such as some persistent pesticides. These may be present in the water at concentrations so low that they cannot be measured even by very sensitive instruments. The chemicals, however, biologically accumulate (bioaccumulate) in the organism and become concentrated at levels that are much higher in the living cells than in the open water. This is especially true for persistent chemicals
substances that do not break down readily in the environment
like DDT and PCBs that are stored in fatty
tissues.
The small fish and zooplankton eat vast quantities of phytoplankton. In doing so, any toxic chemicals accumulated by the phytoplankton are further concentrated in the bodies of the animals that eat them. This is repeated at each step in the food chain. This process of increasing concentration through the food chain is known as biomagnification.
The top predators at the end of a long food chain, such as lake trout, large salmon and fish-eating gulls, may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low. The concentration of some chemicals in the fatty tissues of top predators can be millions of times higher than the concentration in the open water.
The eggs of aquatic birds often have some of the highest concentrations of toxic chemicals, because they are at the end of a long aquatic food chain, and because egg yolk is rich in fatty material. Thus, the first harmful effects of a toxic chemical in a lake often appear as dead or malformed chicks. Scientists monitor colonies of gulls and other water birds because these effects can serve as early warning signs of a growing toxic chemical problem. They also collect gull eggs for chemical analysis because toxic
chemicals will be detectable in them long before they reach measurable levels in the open water.
Research of this kind is important to humans as well, because they are consumers in the Great Lakes food chain. Humans are at the top of many food chains, but do not receive as high an exposure as, for example, herring gulls. This is because humans have a varied diet that consists of items from all levels of the food chain, whereas the herring gull depends upon fish as its sole food source. Nevertheless, the concerns about long-term effects of low-level exposures in humans, as well as impacts on people who do eat a lot of contaminated fish and wildlife, highlight the importance of taking heed of the well-documented adverse effects already seen in the ecosystem..............................................
the ecosystem.
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atlas017
FISH CONSUMPTION ADVISORIES
In 1971, the first sport fish advisory was issued in the Great Lakes, for people consuming fish caught from the lakes. These advisories, issued by state and provincial governments, recommended that consumption of certain species and sizes of sport-caught fish should be limited or avoided due to toxic chemicals present in the fish. Advisories are now issued on a regular basis to limit exposure and protect health (for example, Lake Ontario and Lake Superior).
Because of current scientific uncertainty about the toxicity to humans of these chemicals, the jurisdictions surrounding the lakes vary in the advice they provide. However, in all cases, following the advisories will reduce the exposure to contaminants, and therefore the risk of suffering adverse effects. People who consume lots of sport-caught fish should pay close attention to the advisories. Because the developing fetus and child are most susceptible to the adverse effects of exposure, the fish consumption guidelines are strictest for women of child-bearing age, pregnant women, and pre-teen children.
Fish provide important nutrition to people and, while following advisories can reduce exposure, fish can also be prepared and cooked in certain ways so as to reduce or eliminate a large proportion of certain contaminants. Since some persitent contaminants accumulate in fat tissue, trimming visible fat and broiling rather than frying so that fat drips away will reduce a
large proportion of these contaminants in fish. Limiting consumption of fish organs will reduce exposure to mercury. Fish advisory information in the form of fish guides or pamphlets often includes this fish preparation information. Consumers should contact their public health and environmental agencies for further information about fish advisories and preparing and eating fish from the Great Lakes or their tributaries.
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atlas021
1909
THE BOUNDARY WATERS TREATY OF 1909
In 1905 the International Waterways Commission was created to advise the governments of both countries about levels and flows in the Great Lakes, especially in relation to the generation of electricity by hydropower. Its limited advisory powers proved inadequate for problems related to pollution and environmental damage. One of its first recommendations was for a
stronger institution with the authority for study of broader boundary water issues and the power to make binding decisions.
The Boundary Waters Treaty was signed in 1909 and provided for the creation of the International Joint Commission (IJC). The IJC has the authority to resolve disputes over the use of water resources that cross the international boundary. Most of its efforts for the Great Lakes have been devoted to carrying out studies requested by the governments and advising the governments about problems.
In 1912, water pollution was one of the first problems referred to the IJC for study. In 1919, after several years of study, the IJC concluded that serious water quality problems required a new treaty to control pollution. However, no agreement was reached.
Additional studies in the 1940s led to new concerns by the IJC. The Commission recommended that water quality objectives be established for the Great Lakes and that technical advisory boards be created to provide continuous monitoring and surveillance of water quality.
Public and scientific concern about pollution of the lakes grew as accelerated eutrophication became more obvious through the 1950s. In 1964 the IJC began a new reference study on pollution in the lower Great Lakes. The report on this study in 1970 placed the principal blame for eutrophication on excessive phosphorus.
The study proposed basin-wide efforts to reduce phosphorus loadings from all sources. It was recognized that reduction of phosphorus depended on control of local sources. Uniform effluent limits were urged for all industries and municipal sewage treatment systems in the basin. Research suggested that land runoff could also be an important source of nutrients and other pollutants into the lakes. The result of the reference study was the signing of the first Great Lakes Water Quality Agreement in 1972.
HE GREAT LAKES FISHERIES COMMISSION
During the 1950s and 1960s, problems on the Great Lakes came to
a head. The parasitic sea lamprey had decimated fisheries as it
invaded further into the waterway. In 1955 the binational Great
Lakes Fisheries Commission was established to find a means of
control for the lamprey. By the late 1970s the lamprey population
had been reduced by 90 percent with use of selective chemicals to
kill the larvae in streams. Since then, the Fisheries Commission
has expanded its activities to include work to rehabilitate the
fisheries of the lakes coordinating government efforts to stock
and restore fish populations.a
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atlas023
ommission
During the 1950s and 1960s, fisheries problems on the Great Lakes came to a head. The parasitic sea sea lamprey had decimated fisheries as it invaded further into the waterway. In 1955 the binational Great Lakes Fishery Commission was established to find a means of control for the lamprey. By the late 1970s the lamprey population had been reduced by 90 percent with use of selective chemicals to kill the larvae in streams. Since then, the Fisheries Commission has expanded its activities to include work to rehabilitate the fisheries of the lakes coordinating government efforts to stock and restore fish populations......ions...........................................
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atlas024
THE GREAT LAKES WATER QUALITY AGREEMENT - 1972
The Great Lakes Agreement established common water quality objectives to be achieved in both countries and three processes that would be carried out binationally. The first is control of pollution, which each country agreed to accomplish under its own laws. The chief objective was reduction of phosphorus levels to no more than l ppm (mg per liter) in discharges from large sewage treatment plants into lakes Erie and Ontario together with new limits on industry. Other objectives included elimination of oil, visible solid wastes and other nuisance conditions.
The second process was research on Great Lakes problems to be carried out separately in each country as well as cooperatively. Both countries established new Great Lakes research programs. Major cooperative research was carried out on pollution problems of the Upper Great Lakes and on pollution from land use and other sources.
The third process was surveillance and monitoring to identify problems and to measure progress in solving problems. Initially, water chemistry was emphasized and levels of pollutants were reported. Now, the surveillance plan is designed to assess the health of the Great Lakes ecosystem and increasingly depends on monitoring effects of pollution on living organisms.
The agreement provided for a review of the objectives after five years and negotiation of a new agreement with different objectives if necessary. Tangible results had been achieved when the review was carried out in 1977. The total discharge of nutrients into the lakes had been noticeably reduced. Cultural, or man-made eutrophication, bacterial contamination and the more obvious nuisance conditions in rivers and nearshore waters had declined. However, new problems involving toxic chemicals had been revealed by research and the surveillance and monitoring program.
Public health warnings had been issued for consumption of certain species of fish in many locations. Sale of certain fish was prohibited due to unsafe levels of PCBs, mercury and, later, mirex and other chemicals. In 1975, discovery of high levels of PCBs in lake trout on Isle Royale in Lake Superior demonstrated that the lakes were receiving toxic chemicals by long range atmospheric transport. These developments and the results of studies that were carried out after the 1972 Agreement set the stage for the next major step in Great Lakes management.
The Upper Lakes study concluded that phosphorus objectives should be set for lakes Huron, Michigan and Superior. This development was significant because it recognized the Great Lakes as a single system and called for joint management objectives for Lake Michigan and its tributaries that had not previously been considered boundary waters.
The study on pollution from land use and other nonpoint sources was known as PLUARG (Pollution from Land Use Activities Reference Group). The study demonstrated that runoff from agriculture and urban areas was affecting water quality in the Great Lakes. This significant development confirmed that control of direct discharge of pollution from point sources alone into the Great Lakes and tributaries would not be enough to achieve the water quality objectives. It also called for control of nonpoint pollution into the Great Lakes from land runoff and the atmosphere.
The experience under the 1972 Agreement demonstrated that, despite complex jurisdictional problems, binational joint management by Canada and the United States could protect the Great Lakes better than either country could alone. In 1978, a new Great Lakes Water Quality Agreement was signed that preserved the basic features of the first agreement and built on the previous results by setting up a new stage in joint management.......ment....................ment.........ment..........ment........ment....................ment.
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THE GREAT LAKES WATER QUALITY AGREEMENT - 1978
Like the 1972 Agreement, the new agreement called for achieving common water quality objectives, improved pollution control throughout the basin, and continued monitoring by the IJC. As part of improved pollution control, the 1978 Agreement called for setting target loadings for phosphorus for each lake and for virtual elimination of discharges of toxic chemicals. The target loadings were a step toward a new management goal that has come to be called "an ecosystem approach."
In contrast to the earlier agreement which called for protection of waters of the Great Lakes, the 1978 agreement calls for restoring and maintaining "the chemical, physical and biological integrity of the entire Great Lakes Basin Ecosystem." The ecosystem is defined as "...the interacting components of air, land and water and living organisms including man within the drainage basin of the St. Lawrence River."
In calling for target loadings for phosphorus, the 1978 agreement introduced the concept of mass balance into Great Lakes management. A target loading is the level that will not cause undesirable effects, including over-production of algae and anoxic conditions on lake bottoms. The mass balance approach
calculates the amount of pollutant that remains active after all sources and losses are considered. All sources of phosphorus are considered in setting the controls that are needed to reach the target loading. Formerly phosphorus control was based on setting effluent limits to reduce pollution from direct discharges. Target loadings based on mass balance use mathematical models to determine levels of control that should protect the integrity of the ecosystem.
The 1978 agreement called for virtual elimination of the discharge of persistent toxic chemicals because of severe and irreversible damage from bioconcentration of toxic substances present at very low levels in water. The effects include birth defects and reproductive failures in birds, and tumors in fish. A long term epidemiological study in Michigan has since indicated that exposure to high concentrations of PCBs before birth, affects the development of human infants. The elevated levels of PCBs in the mothers of these babies was due to consumption of certain fish from Lake Michigan.
Success in reducing phosphorus loadings under the Great Lakes agreement has provided a model to the world in binational resource management. The use of the mass balance approach for phosphorus set the stage for the much more difficult task of controlling toxic contamination. Further progress in cleaning up pollution from the past and preventing future degradation depends on fully applying an ecosystem approach to management.......ds
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THE GREAT LAKES WATER QUALITY AGREEMENT - 1987
In 1987 the Agreement was revised to strengthen management provisions; call for development of ecosystem objectives and indicators; and to address nonpoint sources of pollution, contaminated sediment,airborne toxic substances, and pollution from contaminated groundwater. New management approaches included development of Remedial Action Plans (RAPs) for geographic Areas of Concern and Lakewide Management Plans (LAMPs) for Critical Pollutants.
The ecosystem approach was strengthened by calling for development of ecosystem objectives and indicators and by focusing RAPs and LAMPs on elimination of impairments of beneficial uses. The uses include various aspects of human and and aquatic community health and specifically include habitat. By clearly focusing management activities on endpoints in the living system, additional meaning is given to the goal of restoring and maintaining the integrity of the Great Lakes Basin ecosystem.
The agreement to prepare Lakewide Management Plans includes a
commitment to develop a schedule of reductions in loads of critical pollutants entering the lakes in order to meet water quality objectives and restore beneficial uses. Thus the mass balance concept developed for phosphorus is being applied to control of toxic substances into the Great Lakes. Although total elimination of toxic substances from the Great Lakes basin is the goal, the mass balance approach can be used to set priorities and direct pollution control efforts.
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atlas025
THE INTERNATIONAL JOINT COMMISSION
The 1909 Boundary Waters Treaty established the International Joint Commission of Canada and the United States. The treaty created a unique process for cooperation in the use of all the waterways that cross the border between the two nations, including the Great Lakes.
The IJC has six members, three appointed from each side by the heads of the federal governments. The authors of the 1909 Boundary Waters Treaty saw the Commission not as separate national delegations, but as a single body seeking common solutions in the joint interests of the two countries. All members are expected to act independently of national concerns and few IJC decisions have split along national lines.
The IJC has three responsibilities for the Great Lakes under the original treaty. The first is the limited authority to approve applications for the use, obstruction or diversion of boundary waters on either side of the border that would affect the natural level or flow on either side. Under this authority it is the IJC that determines how the control works on the St. Marys River and the St. Lawrence River will be operated to control releases of water from Lakes Superior and Ontario. It also regulate flows into Lake Superior from Long Lake and Lake Ogoki.
The second responsibility is to conduct studies of specific problems under references, or requests, from the governments. The implementation of the recommendations resulting from IJC reference studies is at the discretion of the two governments. When a reference is made to the IJC, the practice has been to commission a board of experts to supervise the study and to conduct the necessary research. A number of such studies have been undertaken in the history of the IJC.
The third responsibility is to arbitrate specific disputes which may arise between the two governments in relation to boundary waters. The governments may refer any matters of difference to the Commission for a final decision. This procedure requires the approval of both governments and has never been invoked.
In addition to these specific powers under the 1909 Treaty, the IJC provides a procedure for monitoring and evaluating progress under the Water Quality Agreement. For this purpose two standing advisory boards are called for in the Agreement.
The Water Quality Board is the principal advisor to the Commission and consists mainly of high level managers from federal, state and provincial agencies selected equally from both countries. Its responsibilities include evaluating progress being made in implementation of the Agreement and promoting coordination of Great Lakes programs among the different levels of government.
The Science Advisory Board consists primarily of government and academic experts who advise the Water Quality Board and the IJC about scientific findings and research needs. The Council of Great Lakes Research Managers in addition to the Science Advisory Board was established to provide effective guidance, support and evaluation for Great Lakes research programs. Both groups have substructures involving special committees, task forces and work groups to address specific issues.
The IJC relies on work done by the various levels of the two governments and the academic community. It maintains an office in each of the national capitals and a Great Lakes Regional Office in Windsor, Ontario. The Great Lakes Office provides administrative support and technical assistance to the boards and a public information service for the programs of the Commission.
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The Great Lakes Water Quality Agreement recognizes that control procedures, research and monitoring would continue to be conducted
by the two countries within their respective legislative and administrative structures.
Because of their obligations under the Agreement, both governments have established special programs for the Great Lakes.
In Canada, the British North America Act assigns the authority for navigable waters and international waters to the federal government, while pollution control and the management of natural resources are primarily provincial responsibilities. Consequently, the initiative to establish water quality objectives under the Great Lakes Water Quality Agreement has been federal/provincial, and the implementation has been primarily a provincial responsibility.
The federal Canada Water Act provides for federal/provincial agreements setting out responsibilities for both levels of government. The Canada/Ontario Agreement provides for joint work on activities required by the Great Lakes Water Quality Agreement.
In 1988, the Canadian Environmental Protection Act (CEPA) was developed, and provides a framework for controlling toxic substances. For example, under this act, dioxins and furans will be virtually eliminated from pulp and paper mill discharges.
The lead agency at the federal level is Environment Canada. The Department of Fisheries and Oceans is a major contributor of scientific and research support to Canada
s Great Lakes program. Other federal departments directly involved include the Department of Health, Agriculture and Agrifood Canada, Transport Canada and the Department of Government Services.
The major responsibility for water quality at the provincial level rests with the Ontario Ministry of Environment and Energy (MOEE). The MOEE is responsible for establishing individual control orders for each industrial discharger. It also provides funding for sewage treatment. The Ontario Ministry of Natural Resources provides leadership for fisheries, forestry and wildlife management.
In the U.S., many federal environmental laws affect the lakes, including the Clean Water Act, the Resource Conservation and Recovery Act, the Toxic Substances Control Act, the Comprehensive Environmental Response and Recovery Act (Superfund) and the National Environmental Policy Act. These statutes provide federal regulatory authority, but it is federal policy to delegate regulatory authority to the state governments wherever possible. The states have their own laws and operate using both state and federal funding.
Two considerations determine the level of control required by U.S. laws. The first requires all municipal and industrial dischargers to meet minimum national effluent standards for pollution control. Secondly, if further limits are necessary to meet ambient environmental standards, tighter limits can be imposed.
For meeting U.S. obligations under the Great Lakes Water Quality Agreement, the U.S. Environmental Protection Agency (EPA) has the lead responsibility. Numerous other agencies also have important roles, particularly the U.S. Fish and Wildlife Service, the U.S. National Biological Service and the U.S. Coast Guard.
The federal government supports Great Lakes Research in several agencies. The Great Lakes National Program Office in the EPA regional offices at Chicago provides funding for applied research and coordinates its activities with EPA research laboratories in Grosse Ile, Michigan, Duluth, Minnesota and elsewhere.
The National Oceanic and Atmospheric Administration (NOAA) has a Great Lakes Environmental Research Laboratory and the U.S. Fish and Wildlife Service maintains laboratories at the National Fisheries Center in Ann Arbor, Michigan. The Army Corps of Engineers carries out research on water quality as well as water quantity. A network of Sea Grant College programs is supported by state and federal funding at universities in seven of the Great Lakes states.
in seven of the Great Lakes states.
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literature
Allardice, D., and S. Thorp. STATE OF THE LAKES ECOSYSTEM CONFERENCE WORKING PAPER: A CHANGING GREAT LAKES ECONOMY: ECONOMIC AND ENVIRONMENTAL LINKAGES. Environment Canada and United States Environmental Protection Agency, 1994.
Allen, Robert. THE ILLUSTRATED NATURAL HISTORY OF CANADA: THE GREAT LAKES. Toronto: McClelland and Stewart, 1970.
ALTERNATIVES: PERSPECTIVES ON SOCIETY, TECHNOLOGY AND ENVIRONMENT. Special Issue. Saving the Great Lakes. Vol. 13, No. 3, September/October, 1986.
American Museum of Natural History. THE ENDURING GREAT LAKES. J. Rousmaniere (ed.). New York: W.W. Norton and Co., 1980.
Ashworth, William. THE LATE, GREAT LAKES. New York: Knopf, 1986.
Burns, Noel M. ERIE: THE LAKE THAT SURVIVED. Totowa, New Jersey: Rowman and Allanheld Publ., 1985.
Egerton, Frank N. OVERFISHING OR POLLUTION? CASE HISTORY OF A CONTROVERSY ON THE GREAT LAKES. Great Lakes Fishery Commission, Technical Report No. 41, Ann Arbor, Michigan, 1985.
Eichenlaub, Val. WEATHER AND CLIMATE OF THE GREAT LAKES BASIN. Notre Dame, Indiana: University of Notre Dame Press, 1979.
Eisenreich, S.J., C.J. Holland and T.C. Johnson. ATMOSPHERIC POLLUTANTS IN NATURAL WATER SYSTEMS. Ann Arbor, Michigan: Ann Arbor Science Publishers, 1980.
Ellis, W.D. LAND OF THE INLAND SEAS: THE HISTORIC AND BEAUTIFUL GREAT LAKES COUNTRY. Palo Alto: American West Publishing Co., 1974.
Emery, Lee. REVIEW OF FISH SPECIES INTRODUCED INTO THE GREAT LAKES, 1819-1974. Great Lakes Fishery Commission, Technical Report No. 45, Ann Arbor, Michigan, 1985.
Environment Canada. GREAT LAKES CLIMATOLOGICAL ATLAS. Saulesleja, A. (ed.). Atmospheric Environment Service. Ottawa: Canadian Government Publications Centre.(Cat. No. EN56-70/1986), 1986.
Environment Canada and United States Environmental Protection Agency. STATE OF THE LAKES ECOSYSTEM REPORT. July, 1995.
Federal Reserve Bank of Chicago and the Great Lakes Commission. THE GREAT LAKES ECONOMY: LOOKING NORTH AND SOUTH. Chicago, 1991.
Government of Canada. CURRENTS OF CHANGE; FINAL REPORT OF THE INQUIRY ON FEDERAL WATER POLICY. Ottawa: Supply and Services Canada, 1985.
Government of Canada. TOXIC CHEMICALS IN THE GREAT LAKES AND ASSOCIATED EFFECTS: SYNOPSIS, VOLUME 2, VOLUME 3. Ottawa: Supply and Services Canada, 1991.
Government of Quebec, St. Lawrence Development Secretariat. THE ST. LAWRENCE: A VITAL NATIONAL RESOURCE. Quebec, P.Q., 1985.
Great Lakes Basin Commission. GREAT LAKES BASIN COMMISSION FRAMEWORK STUDY. Public Information Office, Great Lakes Basin Commission, Ann Arbor, Michigan, 1976.
Great Lakes Fishery Commission. REHABILITATING GREAT LAKES ECOSYSTEMS. G.R. Francis et al. (eds). Technical Report No. 37, Ann Arbor, Michigan, 1979.
Great Lakes Fishery Commission. STRATEGIC VISION OF THE GREAT LAKES FISHERY COMMISSION FOR THE DECADE OF THE 1990S. Ann Arbor, Michigan, 1992.
Hartig, J., and N. Law. PROGRESS IN GREAT LAKES REMEDIAL ACTION PLANS: IMPLEMENTING THE ECOSYSTEM APPROACH IN GREAT LAKES AREAS OF CONCERN. Detroit: Wayne State University, 1994.
Health and Welfare Canada. HAVING YOUR CATCH AND EATING IT TOO: A FEW WORDS ABOUT SPORT FISH AND YOUR HEALTH. Great Lakes Health Effects Program. Ottawa: Supply and Services Canada, 1992.
Health and Welfare Canada. A VITAL LINK: HEALTH AND THE ENVIRONMENT IN CANADA. Ottawa: Supply and Services Canada, 1992.
Hough, J.L. THE GEOLOGY OF THE GREAT LAKES. University of Illinois Press, 1958.
International Joint Commission. AN ENVIRONMENTAL MANAGEMENT STRATEGY FOR THE GREAT LAKES SYSTEM. Final Report, International Reference Group on Great Lakes Pollution from Land Use Activities (PLUARG). Windsor, Ontario, 1978.
International Joint Commission. GREAT LAKES DIVERSIONS AND CONSUMPTIVE USES. Report by the International Great Lakes Diversion and Consumptive Uses Study Board, 1981.
International Joint Commission. REPORT ON GREAT LAKES WATER QUALITY. Report of the Great Lakes Water Quality Board. Presented at Kingston, Ontario, 1985.
International Joint Commission. REVISED GREAT LAKES WATER QUALITY AGREEMENT OF 1978 AS AMENDED BY PROTOCOL SIGNED NOVEMBER 18, 1987.
Jacobsen, Joseph L.
Prenatal Exposure to an Environmental Toxin: A Test of Multiple Effects
, DEVELOPMENTAL PSYCHOLOGY, Vol. 20, No. 4, 1984.
Keating, Michael. TO THE LAST DROP: CANADA AND THE WORLD
S WATER CRISIS. Toronto: Macmillan of Canada, 1986.
Koonce, J. STATE OF THE LAKES ECOSYSTEM CONFERENCE WORKING PAPER: AQUATIC COMMUNITY HEALTH OF THE GREAT LAKES. Environment Canada and United States Environmental Protection Agency, 1994.
Kuchenberg, Tom. REFLECTIONS IN A TARNISHED MIRROR: THE USE AND ABUSE OF THE GREAT LAKES. Sturgeon Bay, Wisconsin: Golden Glow Publishing, 1978.
Le Strang, Jacques (ed.). THE GREAT LAKES - ST. LAWRENCE SYSTEM. Boyne City, Michigan: Harbor House Publishers Seaway Review, 1985.
J. Manno, et al. STATE OF THE LAKES ECOSYSTEM CONFERENCE WORKING PAPER: EFFECTS OF GREAT LAKES BASIN ENVIRONMENTAL CONTAMINANTS ON HUMAN HEALTH. Environment Canada and United States Environmental Protection Agency, 1994.
Marine Advisory Service of the Michigan Sea Grant College Program. LAKE SUPERIOR, MICHIGAN, HURON, ERIE, ONTARIO AND GREAT LAKES BASIN. Extension Bulletins E-1866 - 1871. Cooperative Extension Service, Michigan State University, East Lansing, Michigan, 1993.
Neilson, M., et al. STATE OF THE LAKES ECOSYSTEM CONFERENCE WORKING PAPER: NUTRIENTS: TRENDS AND SYSTEM RESPONSE. Environment Canada and United States Environmental Protection Agency, 1994.
Nriagu, J.A., and M.S. Simmons (eds). TOXIC CONTAMINANTS IN THE GREAT LAKES. New York: John Wiley and Sons, 1984.
Phillips, D.W., and J.A.W. McCulloch. THE CLIMATE OF THE GREAT LAKES BASIN. Toronto: Environment Canada, 1972.
Royal Commission on the Future of the Toronto Waterfront. REGENERATION: TORONTO'S WATERFRONT AND THE SUSTAINABLE CITY: FINAL REPORT. Ottawa: Supply and Services Canada, 1992.
Scott, S., R. Vezina and M. Webb. THE ST. LAWRENCE RIVER: ITS ECONOMY AND ENVIRONMENT. Toronto: The Centre For The Great Lakes Foundation, 1989.
The Nature Conservancy. THE CONSERVATION OF BIOLOGICAL DIVERSITY IN THE GREAT LAKES ECOSYSTEM: ISSUES AND OPPORTUNITIES. Chicago, Illinois, 1994.
TREATY BETWEEN THE UNITED STATES OF AMERICA AND GREAT BRITAIN RELATING TO BOUNDARY WATERS BETWEEN THE UNITED STATES AND CANADA. January 11, 1909. University of Michigan. JOURNAL OF GREAT LAKES RESEARCH. All volumes. Ann Arbor, Michigan.
Wilson, E. O. THE DIVERSITY OF LIFE. New York: W.W. Norton and Company, 1992. World Commission on Environment and Development. OUR COMMON FUTURE. Oxford University Press, 1987.
N FUTURE. Oxford
University Press, 1987.
References and Suggestions for Futher Reading
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Dieldrin
Dieldrin concentrations in Lake Michigan lake trout increased from a mean of 0.27 microg/g in 1970 to 0.58 microg/g in 1979, then they declined to 0.17 micro/g in 1986 and 0.18 microg/g in 1990. While concentrations varied between lakes, the pattern observed in Lake Michigan was also observed in Lakes Superior, Huron and Ontario, i.e., a general decline, but with peaks in 1979 and 1984. In Lake Erie walleye, mean dieldrin concentrations decreased from 0.10 microg/g in 1977 to 0.04 microg/g in 1982, then increased to 0.07 microg/g in 1984, then declined again to 0.03 microg/g in 1990. Between 1979 and 1990, mean dieldrin concentrations declined significantly in the top predator fish from lakes Michigan, Huron and Erie.
Dieldrin concentrations are well below the IJC objective of 0.3 microg/g in whole fish.
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Physical Characteristics of the System
The magnitude of the Great Lakes water system is difficult to appreciate, even for those who live within the basin. The lakes contain about 23,000 km3 (5,500 cu. mi.) of water, covering a total area of 244,000 km2 (94,000 sq. mi.) The Great Lakes are the largest system of fresh, surface water on earth, containing roughly 18 percent of the world supply. Only the polar ice caps contain more fresh water.
In spite of their large size, the Great Lakes are sensitive to the effects of a wide range of pollutants. The sources of pollution include the runoff of soils and farm chemicals from agricultural lands, the waste from cities, discharges from industrial areas and leachate from disposal sites. The large surface area of the lakes also makes them vulnerable to direct atmospheric pollutants that fall with rain or snow and as dust on the lake surface.
Outflows from the Great Lakes are relatively small (less than 1 percent per year) in comparison with the total volume of water. Pollutants that enter the lakes - whether by direct discharge along the shores, through tributaries, from land use or from the atmosphere are retained in the system and become more concentrated with time. Also, pollutants remain in the system because of resuspension (or mixing back into the water) of sediment and cycling through biological food chains.
Because of the large size of the watershed, physical characteristics such as climate, soils and topography vary across the basin. To the north, the climate is cold and the terrain is dominated by a granite bedrock called the Canadian (or Laurentian) Shield consisting of Precambrian rocks under a generally thin layer of acidic soils. Conifers dominate the northern forests.
In the southern areas of the basin, the climate is much warmer. The soils are deeper with layers or mixtures of clays, silts, sands, gravels and boulders deposited as glacial drift or as glacial lake and river sediments. The lands are usually fertile and can be readily drained for agriculture. The original deciduous forests have given way to agriculture and sprawling urban development.
Although part of a single system, each lake is different. In volume, Lake Superior is the largest. It is also the deepest and coldest of the five. Superior could contain all the other Great Lakes and three more Lake Eries. Because of its size, Superior has a retention time of 173 years. Retention time is a measure based on the volume of water in the lake and the mean rate of outflow. Most of the Superior basin is forested, with little agriculture because of a cool climate and poor soils. The forests and sparse population result in relatively few pollutants entering Lake Superior, except through airborne transport.
Lake Michigan, the third largest in area, is the only Great Lake entirely within the United States. The northern part is in the colder, less developed upper Great Lakes region. It is sparsely populated, except for the Fox River Valley, which drains into Green Bay. This bay has one of the most productive Great Lakes fisheries but receives the wastes from the world's largest concentration of pulp and paper mills. The more temperate southern basin of Lake Michigan is among the most urbanized areas in the Great Lakes system. It contains the Milwaukee and Chicago metropolitan areas. This region is home to about 8 million people or about one-fifth of the total population of the Great Lakes basin. Fortunately for the lake, drainage for much of the Chicago area has been redirected out of the Great Lakes Basin.
Lake Huron, which includes Georgian Bay, is the third largest of the lakes by volume. Many Canadians and Americans own cottages on
the shallow, sandy beaches of Huron and along the rocky shores of
Georgian Bay. The Saginaw River basin is intensively farmed and
contains the Flint and Saginaw-Bay City metropolitan areas. Saginaw
Bay, like Green Bay, contains a very productive fishery.
Lake Erie is the smallest of the lakes in volume and is exposed to the greatest effects from urbanization and agriculture. Because of the fertile soils surrounding the lake, the area is intensively farmed. The lake receives runoff from the agricultural area of southwestern Ontario and parts of Ohio, Indiana and Michigan. Seventeen metropolitan areas with populations over 50,000 are located within the Lake Erie basin. Although the area of the lake is about 26,000 km2 (10,000 square miles), the average depth is only about 19 metres (62 feet). It is the shallowest of the five lakes and therefore warms rapidly in the spring and summer, and frequently freezes over in winter. It also has the shortest retention time of the lakes, 2.6 years. The western basin, comprising about one-fifth of the lake, is very shallow with an average depth of 7.4 metres (24 feet) and a maximum depth of 19 metres (62 feet).
Lake Ontario, although slightly smaller in area, is much deeper than its upstream neighbour, Lake Erie, with an average depth of 86 metres (283 feet) and a retention time of about 6 years. Major urban industrial centres, such as Hamilton and Toronto, are located on its shore. The U.S. shore is less urbanized and is not intensively farmed, except for a narrow band along the lake..
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