Great Lakes Report to Congress 1994
REPORT TO CONGRESS ON
THE GREAT LAKES ECOSYSTEM
America's inventive and productive genius has been amply realized in
the Great Lakes region. Early in the last century, steamships and the
Erie Canal helped to open a 2,200 mile waterway into the heart of a
continent. Through this corridor came timber to build a growing nation
and ores to feed the successive industrial ages of iron, then steel.
America's first oil refineries were within the Great Lakes watershed,
helping to spark the region's automobile industry that grew into the
preeminent industry of twentieth century America. The connection of
railroads and canals to the Lakes contributed to unprecedented
agricultural development in the Midwest and Great Plains.
During the twentieth century, fuels and industrial minerals have been
found elsewhere around the world, and modern means of transportation
have made them widely accessible. With the spread of industrial
economies, the Great Lakes region's disproportionate share of world
manufacturing has inevitably eroded. Yet, productive industries, such as
forest products, shipping, agriculture, food processing, chemicals,
mining, metals, and heavy manufacturing continue to be important.
Manufacturing remains the largest sector in the economy of most Great
Lakes States.
Before its development, the Great Lakes region was endowed with
extraordinary natural abundance--oceans of freshwater, splendid forests,
plentiful animals, rich soil, immense wetlands, multitudes of waterfowl.
The Great Lakes were an important part of the breeding range of the
passenger pigeon, one of the most numerous birds in the world. Waters
teemed with fish. Sturgeon up to 6 feet long were common. A fisherman
using a dip net could reap many hundreds of whitefish in a day.
Much of the majesty and plenty of the Lakes remain, although human
actions have often changed or damaged the ecosystem. The last passenger
pigeon died early in the twentieth century, the tragic survivor of a
species exterminated by hunting and the loss of oak and beech forest
habitat. Today, few sturgeon survive. Lake trout populations are not
self-sustaining. A top predator, the bald eagle, breeds with less
success along the shores of the Lakes than inland. Habitat available to
fish and wildlife is greatly reduced, as are their populations.
To help place today's Great Lakes environmental issues in context,
this chapter discusses physical features of the Lakes, their economic
development during the past three centuries, and ecological outcomes
associated with this development.
By many measures, the five Great Lakes are freshwater seas. Formed by
the melting retreat of mile-thick glaciers 10 to 12 thousand years ago,
the Great Lakes water system represents about 18 percent of the world's
surface freshwater and 95 percent of the surface freshwater of the
United States. If poured over the landmass of the continental United
States, the 6 quadrillion gallons of the Lakes would immerse the "lower
48" States to a depth of almost 10 feet. The Lakes and their connecting
channels have 7,437 miles of shoreline across eight States and the
Province of Ontario. Their 201,000 square mile watershed holds nearly
80,000 small lakes--one-third within the United States--that could
collectively cover an area larger than Lake Erie.
By virtue of their size, the Lakes affect the climate of their
region. Heat stored in the Lakes during the summer warms adjacent land
in the winter. Areas of Michigan, southern Ontario, and western New York
have warmer winters than some other parts of North America at similar
latitudes. These same areas, however, receive heavy snowfalls as
prevailing winds from the west pick up moisture over the Lakes. In
spring and summer, the Lakes are slow to warm, cooling nearshore land.
As would be expected across such a large area, the physical
characteristics of the Great Lakes watershed vary. In the north, the
land is heavily forested, particularly by conifers. The soil is
generally thin and acidic, covering an ancient bedrock called the
Laurentian Shield. The climate is cold. Principal industries are timber,
mining, and hydroelectric power. In the south, soils are deeper and
fertile, rocks sedimentary and nutrient rich, temperatures warmer, the
density of human population greater. Vast wetlands and deciduous forests
have generally been replaced by agricultural, industrial, and
residential uses.
By surface area, Lake Superior is the largest freshwater lake in the
world. It is the second largest in water volume, trailing only the
immensely deep Lake Baikal in Siberia. Superior holds just over one-half
of the water in the Great Lakes system. Because of its huge volume,
Superior has a water retention time of 173 years, which is the longest
of the Lakes. The St. Marys River, which flows southeasterly into Lake
Huron, is Superior's outlet.
Lake Michigan is the only Great Lake that lies wholly within the
United States. The second largest Lakes in terms of water volume,
Michigan holds 21 percent of the water in the system. Lake Michigan has
the second longest water retention time, 62 years. Water from Lake
Michigan primarily flows out through the Straits of Mackinac into Lake
Huron. A much smaller outflow is artificially diverted into the
Mississippi River system via the Chicago Sanitary and Ship Canal.
Lake Huron, the second largest Great Lake in terms of surface area,
is slightly larger than Lake Michigan. Huron holds about 16 percent of
the water in the Great Lakes and has a water retention time of 31 years.
Huron's outlet, the St. Clair River, flows into shallow Lake St. Clair
(average depth 11 feet).
Lake Erie is the smallest in water volume, having an average depth of
only 62 feet. Erie has three distinct basins, as defined by water depth
and underwater ridges. The shallow western basin averages 24 feet in
depth. The central basin is deeper; its waters stratify by temperature,
and its narrow bottom layer is vulnerable to depletion of dissolved
oxygen. The eastern basin is the deepest; its bottom layer is thicker
and less vulnerable. Erie has the shortest water retention time, 2.7
years, making it the Lake most responsive to both environmental abuse
and cleanup.
Erie is the southernmost of the Lakes. Its waters are the warmest in
summer and most productive biologically, supporting abundant fisheries.
Because of its shallowness, Erie is the Lake most affected by air
temperature. As a result, it regularly has 95 percent ice cover in the
winter, in contrast to deeper Lake Ontario, which has an average cover
of only l5 percent. Erie's watershed is the most agricultural, most
urban, and least forested; about two-thirds of it is used for farming.
Erie has the highest rate of sedimentation, receiving soil particles
from the rich farmlands of its watershed.
Lake Ontario is the smallest in surface area but contains more than
three times Erie's water volume. The Canadian population within Lake
Ontario's watershed is about twice that of the United States and has
increased significantly during the 1970s and 1980s, while the U.S.
population has remained stable. Canada's largest industrial region lies
along the western and northwestern shores of Lake Ontario and includes
Toronto, a metropolitan area of three million people.
The major source of water to Lake Ontario is the Niagara River
flowing from Lake Erie. Lake Ontario is about 325 feet lower in
elevation than Erie, causing the river to cascade at the famous Niagara
Falls. Ontario's outlet is the St. Lawrence River, which has an annual
flow that represents less than one-half of one percent of the water
volume of the entire Great Lakes system.
This relatively small outflow is a notable characteristic of the
Great Lakes. The system does not flush contaminants quickly. This
attribute makes the Great Lakes ecosystem especially sensitive to
environmental stresses. Another important characteristic of the Lakes is
their clarity. Before intense European settlement of the region began
around 1800, the Lakes contained little phosphorus, were rich in oxygen,
and, with the exception of shallow waters, were very clear. One reason
for these phenomena was that shorelines were rimmed by forests and
wetlands, allowing little nutrient runoff to stimulate production of
microscopic plants (i.e., phytoplankton, such as algae). Although
phytoplankton are the foundation of the Great Lakes food web, excessive
algal growth clouds water. Despite today's level of development, most of
Superior and Huron remain very clear, as do parts of the northern basin
of Lake Michigan.
The most biologically productive areas are Green Bay, Saginaw Bay,
and western Lake Erie, relatively warm shallow waters that are fed,
respectively, by the Fox, Saginaw, and Maumee Rivers The Lakes sustain a
rich diversity of birds and other wildlife. Following the Atlantic and
Mississippi flyways, an estimated three million waterfowl migrate
through the Great Lakes each year, relying on them for food and shelter.
During their spring and fall migrations, up to 25,000 birds of prey can
be observed each day from Whitefish Point in eastern Lake Superior. The
Lakes host multitudes of cormorants, egrets, gulls, herons, and terns.
Native animals include deer, fox, moose, wolves, and fur-bearing
mammals-- beaver, mink and muskrat--that fueled the early development of
the region by European settlers.
During the past 300 years, various industries have boomed in the
Great Lakes region. Fur trapping, especially of beavers, thrived from
the last half of the seventeenth century until the early nineteenth
century. As trapping depleted beaver populations in the region, the fur
trade expanded westward to California, Oregon, the Arctic Ocean. Even
after trapping had moved west, the Lakes remained vital to the industry
for waterborne transportation. The Lakes and St. Lawrence River provided
a pathway for canoes laden with animal pelts to the Atlantic coast where
furs were shipped to customers in Europe. Many early settlements in the
region were fur-trading posts, including Chicago, Detroit, Duluth, and
Green Bay. Chicago's first non-Native American settler, Jean Baptiste
Pointe du Sable, a Haitian of African and French descent, was a fur
trader who built a cabin beside the Chicago River in 1779.
As the beaver industry declined because of the scarcity of beavers
and whims of fashion, early settlers began harvesting trees on a large
scale. Three principal types of forests surrounded the Lakes. Spruce and
fir trees grew in the north on the Laurentian Shield above Superior and
down the eastern shore of Huron. Birch, hemlock, and pines ranged south
of Lake Superior to northern Michigan, north of Lake Erie, and around
Lake Ontario. Hardwoods, such as ash, oak, maple, and dogwood, grew
south of this region. Settlers cleared land for agriculture and
buildings. Commercial logging began in the l830s, after the opening of
the Erie Canal and the advent of steamships, which provided access to
eastern markets. Logging began in Michigan and soon extended to
Minnesota and Wisconsin. Loggers cut softwoods first, chiefly white
pine, often hundreds of years old and more than 100 feet high. Softwoods
framed homes and ships. Hardwoods became barrels and furniture.
The heyday of lumbering was from 1850 to 1900. Grand Rapids, today
Michigan's second largest city, was a sawmill boom town in the 1850s;
later it earned renown as a center for furniture-making. During the
1890s, there were 100 sawmills adjacent to the Saginaw River; by tonnage
shipped, Saginaw was the largest port on the Lakes. Tugboats pulled
enormous floating trains of trees from Canada to Saginaw mills. Around
Muskegon Lake, beside Lake Michigan, there were 50 active sawmills in
1900. By 1910, there were none.
The Great Lakes lumber industry ran out of trees early in the
twentieth century. The climate and soils of the North Woods and the
Laurentian Shield are generally not conducive to farming. With the
passage of time, forests have now returned to much of their former
domain in the northern half of the region, though trees are much younger
and smaller than their predecessors. Today, these woods are harvested
for paper. The paper-making industry, which started in the 1860s,
remains important in both the United States and Canada. In 1982, the
forest industry of Michigan, Minnesota, and Wisconsin employed about
150,000 people and had sales of $15 billion. An additional 80,000
persons were employed in forest recreation.
The mining industry grew concurrently with the lumber industry and
remains important today. In 1845, rich iron ore was found in the
Marquette Range of Michigan's upper peninsula. Additional iron ranges
were later discovered in Minnesota and Wisconsin. In 1855, completion of
the Sault Canal opened Lake Superior to shipping and permitted mining of
these ranges.
Iron ore from the mineral-rich Lake Superior watershed helped to make
the Great Lakes region a center of iron-making, steel-making, and heavy
manufacturing. Ore was shipped to lakeside cities, such as Buffalo,
Cleveland, Detroit, Gary, and, in Canada, Hamilton and Sault-Sainte
Marie. Another key ingredient for steel-making, limestone, was quarried
near the northeast shore of Michigan peninsula. Coal from Illinois,
Ohio, and Pennsylvania fired industrial hearths.
Oil became another significant industry. The world's first oil well
was tapped in the northwestern Pennsylvania town of Titusville in 1859.
Oil was later found near the Lakes in such locations as Midland,
Michigan; Toledo, Ohio; and north-east of Lake St. Clair. Cleveland,
Ohio, already an industrial hub in part because it was the terminus of a
canal that linked the Lakes to the Ohio River, became the Nation's
oil-refining center. In 1863, a 23-year old bookkeeper, John D.
Rockefeller, invested $4,000 in a Cleveland oil refinery. By 1880, his
Standard Oil Company refined 95 percent of the Nation's oil.
Since iron ore, limestone, coal, oil, and waterborne transportation
were readily available, the Great Lakes region became an industrial
heartland of both the United States and Canada. The automotive industry
was born in a Michigan triangle bounded by Lansing, Flint, and Detroit,
supplanting the carriage industry that had been thriving there.
Detroit's population soared by almost 400 percent between 1890 to 1920
as Ford Motor Company began mass production of automobiles. The Ford,
Chrysler, and General Motors corporations were producing eight million
vehicles a year by 1950.
Industries associated with the automotive business, such as tool and
die, machining, aluminum and rubber, were drawn to the area. By the
1920s, Akron, Ohio, where Benjamin Goodrich had open a rubber factory in
l871, was processing almost half the world's rubber. Proximity to the
steel industry attracted appliance and agricultural equipment
manufacturers. Proximity to industrial customers attracted chemical
manufacturers. Brine wells in southeastern Michigan were appealing to
chemical firms. To draw on these wells, Herbert Dow founded what became
one of America's largest chemical firms, Dow Chemical Company, in
Midland, Michigan, in 1891.
During the 1970s and early 1980s, foreign competition and rising
energy costs caused red-ink and job losses in Great Lakes heavy
industry, especially in the United States. By that time, foreign
economies devastated by the Second World War had developed strong
competitors to Detroit's automobile manufacturers. The demand for
fuel-efficient cars made lighter materials, such as plastics and
aluminum, desirable alternatives to steel. During the 1970s, Detroit
lost 20 percent of its residents. About one million manufacturing jobs
disappeared in the early 1980s in just five Great Lakes States.
Yet heavy industries, including mining, steel, machine tools, and
cars, remain important. Today, manufacturing continues to be the largest
sector in the economy of most Great Lakes States. In 1991, five Great
Lakes States made 61 percent of the cars produced in America. Mining and
manufacturing are also major elements in the economy of the Province of
Ontario. The Sudbury area produces the largest quantity of nickel in the
world. Ontario is a major producer of gold, silver, platinum, uranium,
zinc, iron, copper, salt, and gypsum. The province produces nearly 50
percent of Canada's manufactured goods. Employment in Ontario's
manufacturing sector has increased over the last 20 years.
Agriculture is another productive element of the regional economy.
During the nineteenth century, cheap land blessed with ample top soil,
flat terrain, and railroads that brought crops to distant markets
contributed to extraordinary agricultural productivity in the American
Midwest. After 1914, combustion engines supplanted horses in powering
farm machinery. Since 1950, farm yields have soared further because of
developments in biology, chemistry, and engineering. Breeding plants has
provided varieties with higher yields. Fertilizers, especially nitrogen,
have raised soil productivity, and pesticides have abated crop losses to
weeds, fungi, and insects. Farm machines have become vastly more
effective.
As a result of these developments, agricultural output within the
U.S. Great Lakes watershed has increased during the last 40 years,
although farm acreage has actually decreased by one-third. Cropland
accounts for 18 percent of the land in the U.S. counties of the
watershed, predominantly in the south. Corn is the largest crop (42
percent of farm acreage), followed by soybeans (24 percent), and small
grains, especially wheat (17 percent). Dairy products, fruits,
vegetables, and tobacco are also important.
Convenient waterways have abetted the regional economy. The Erie
Canal, completed in 1825, connected Buffalo to the Hudson River at
Albany. At the same time, Canada constructed the Lachine Canal to bypass
rapids on the St. Lawrence and the first Welland Canal between Lakes
Ontario and Erie to bypass Niagara Falls. The 27-mile long Welland has
been enlarged a number of times.
The five parallel locks at Sault-Sainte Marie, connecting Lakes
Superior and Huron, are among the busiest in the world. In 1990, 5,000
vessels carried 90 million tons of cargo (including 50 million tons of
iron ore) through these locks. Many commercial vessels are headed to or
from the port of Duluth/Superior, which ranked 14th in the United States
by tonnage shipped in 1987, and Thunder Bay, Ontario, the port of
embarkation for one-half of Canada's grain production.
The St. Lawrence Seaway connects Lake Ontario to Montreal and
provides the final link in a 2,200 mile commercial waterway between
Duluth and the Atlantic Ocean. Completed in 1959, the Seaway is 27 feet
deep, as are the shipping channels that cut through the St. Marys, St.
Clair, and Detroit Rivers, and Lake St. Clair. This inland waterway is
navigable by one-third of the world's saltwater fleet. In 1989, 40
million tons of cargo passed through the Seaway.
The waters of the Lakes provide other economic benefits. They are a
source of drinking water to millions. Industries use water to make
products (as in the beer for which Milwaukee is famous) and to cool
manufacturing processes. Some rivers are harnessed to generate
electricity; up to one-half the natural flow of the Niagara River is
diverted for this purpose.
Another large element of the Great Lakes economy is recreation,
including sight-seeing, fishing, boating, camping, and hiking. In 1988,
Michigan had more registered boat owners than any other State. The Lakes
sustain both sport and commercial fisheries, although recreational
fishing is more important today. As the value of recreational fishing
has increased, some jurisdictions have established policies that favor
sport fishing. The Great Lakes Fisheries Commission has estimated that
five million sport fisherman on the Great Lakes spent $2 billion in
1985; during the same year, the value of the commercial fish catch was
just $41 million. The largest recorded commercial harvests were in 1889
and 1899. By weight, the commercial yield in recent years has been about
two-thirds of these peak years, yet the value is small since the size
and species harvested are less desirable.
At the onset of the twentieth century, the human population of the
watershed was slightly more than 10 million. According to 1986 census
data, the region has 35 million residents--27.5 million U.S. citizens
and 7.5 million Canadians. The Lake Superior and Lake Huron watersheds
are sparsely inhabited. The south and southwestern shoreline of Lake
Michigan, the Canadian shore of Lake Ontario, and the U.S. side of Lake
Erie are heavily populated. The third and sixth most populated U.S.
metropolitan areas (Chicago and Detroit) and the largest Canadian
metropolitan area (Toronto) are situated near the Lakes. Native American
tribes also reside in the region. Five U.S. Indian reservations lie
adjacent to the shores of the Great Lakes; 14 do so on the Canadian
side.
Some Ecological Impacts of Development
Intense development of the Great Lakes region has wrought vast
changes to its ecosystem. Humans have altered habitat, introduced exotic
(i.e., nonnative) species, and contaminated the Lakes.
Some effects have been dramatic. Through discharge of raw sewage into
the Lakes, cities infected their water supplies with typhoid and cholera
during the late nineteenth and early twentieth centuries. By the
mid-195Os, nonnative sea lamprey (parasitic eel-like fish) decimated
lake trout to the extent that commercial catches in Lakes Huron and
Michigan fell to 1 percent of the yield obtained 20 years before. By the
1960s, mats of algae fouled Lake Erie beaches and water intakes. In
1967, millions of another exotic fish, alewife, washed up on the Lake
Michigan shore, victims of the combined effects of cold weather and
starvation. Overpopulation, related to the decline of alewife predators,
such as lake trout, contributed to the massive die-off. In 1969, a
stretch of the Cuyahoga River in Cleveland was so laden with oil
products, chemicals, and debris that it caught fire. Since the 1960s,
researchers have noted reproductive problems in birds, such as
double-crested cormorants, which have been born with grotesquely crossed
beaks. These problems are probably caused by bioaccumulative toxic
chemicals.
Many of these once acute problems have abated. Treatment of both
drinking water and sewage ended water- related epidemics. Application of
a toxicant to spawning grounds slashed the population of sea lamprey,
although this exotic species is firmly established as a resident of the
Lakes. Stocking of lake trout bolstered their numbers; however, the
species generally is unable to sustain itself. Reductions in loadings of
phosphorus have lessened many problems associated with nutrient
over-enrichment, such as excessive algae. Stocking of salmon and trout
has helped to control alewife numbers. Since the passage of the Clean
Water Act in 1972, the reduction in pollutant loadings has greatly
improved overall water quality, allowing fish to return to some harbors
from which they had disappeared. The health of many fish and wildlife
populations has improved as their burdens of contaminants have declined.
Yet the Great Lakes ecosystem has been pervasively changed in other,
less dramatic ways, many of which are permanent. The decline in the
beaver population resulted in fewer beaver dams, which had impeded
tributaries and helped to create wetlands. In their absence, river flows
increased; faster rivers captured and carried more silt, burying the
spawning grounds of fish.
Harvesting trees exposed soil to direct sunlight, causing drying, and
to wind and water, causing erosion. This, in turn, added silt to rivers.
Forests had provided shade along tributaries. In their absence, the
temperature of streams increased, further modifying the fish habitat.
Forest clearance also increased seasonal variation in tributary flow.
Low wintertime flow exposed streambeds, freezing fish eggs.
Agriculture also increased soil erosion. Since 1950, eroding soil
particles and rainfall runoff have carried agricultural
chemicals--pesticides and fertilizers. The over-enrichment of Lake Erie
was partly the result of increased nutrient use by farmers.
The growth of human population has imposed further ecological change.
Roads, sidewalks, roofs, and parking lots distort natural infiltration
of water into the ground. Rain that would otherwise seep into the soil
is caught by drainage systems and discharged to streams. As a result,
tributaries have become more variable in their flow and less hospitable
to fish.
The Lakes have been extensively altered for shipping and flood
control. River mouths, critical habitat for fish and wildlife, have
especially attracted development. Hundreds of them have been dredged and
surrounded by breakwaters. Dredging and the wash from ship propellers
injure organisms in bottom sediments upon which fish feed. Canals and
ships have introduced nonnative species. Unchecked by natural predators,
some of these have profoundly damaged native species.
Wetlands and sand dunes are two other habitats modified by humans.
Wetlands have vital ecological functions, serving as nursery, resting,
and breeding habitat for fish and wildlife. Perhaps two-thirds of the
region's wetlands have been drained or filled since 1800. The downtown
areas of Chicago, Detroit, and Milwaukee largely rest on filled-in
wetlands. In fact, Chicago takes its name from an Indian word for the
wild garlic that once grew there in marshlands beside Lake Michigan.
Before parks were established to preserve the remaining sand dunes at
the base of Lake Michigan, home to a rich diversity of wildlife, were
mined for glass production and for railway bed fill. Cheap lakefront
land and a large nearby labor force in Chicago also made the dunes and
adjacent wild rice swamps attractive to heavy industry. Standard Oil
Company (now Amoco) established a refinery in Whiting, Indiana, in 1889.
Inland Steel Company opened in East Chicago in 1901. The city of Gary
took its name from the surname of the chairman of United States Steel
when America's first billion dollar corporation opened a huge works
there in 1906. Bethlehem, National, and LTV steel companies followed.
Today, northwestern Indiana is home to numerous metal, oil, and
petrochemical facilities. In places, large amounts of oil float on the
groundwater, during drought, the sinking water table lowers oil into
municipal drainage systems. The Grand Calumet River meanders through
this region receiving most of its waters from industrial and municipal
dischargers. Its riverbed holds many toxic contaminants.
Manufacturing firms have contributed a broad range of contaminants to
the Lakes. One of the most injurious is the family of organic chemical
compounds called polychlorinated biphenyls (PCBs). PCBs were widely used
from 1929 until EPA prohibited their manufacture in 1977. They are
highly stable, which made them useful as hydraulic fluids and lubricants
in high temperature or pressure processes. Tests have shown that PCBs
may cause reproductive disorders, birth defects, and cancers in
laboratory animals. The stability that made PCBs desirable in commercial
applications has undesirable environmental consequences; they magnify up
the Great Lakes food web and do not degrade. PCB contamination is the
most frequent grounds for health advisories regarding consumption of
Great Lakes fish.
Though the practice ceased during the 1970s, some chloralkali plants
and some pulp and paper mills released mercury that was later detected
in fish from Lake Huron, Lake St. Clair, western Lake Erie, eastern Lake
Ontario, and the St. Lawrence River at levels that required closure of
some commercial fisheries. In the 1980s, EPA also recognized that pulp
and paper mills, particularly those using the bleached kraft process,
discharge very low concentrations of chlorinated dibenzodioxins and
dibenzofurans as byproducts of pulp and paper bleaching with chlorine.
Dioxins and furans represent a family of 210 related chemical compounds.
The most infamous of the dioxin compounds, 2,3,7,8-TCDD, produces a
variety of toxic effects in laboratory animals at very low doses.
The pulp and paper industry also continues to be a significant source
of conventional pollutants to the Lakes, particularly to Lake Superior.
According to a 1989 report by the International Joint Commission, pulp
and paper mills in the Province of Ontario generally do not use
secondary (i.e., biological) processes to treat their wastewater.
Secondary treatment, usually practiced by U.S. mills, decreases both
conventional pollutants and 25 to 60 percent of toxic organic
byproducts. In 1993, the Province of Ontario announced a multiyear
phase-in of enhanced discharge requirements for this industrial sector.
Chemical companies have left a toxic heritage in the groundwater,
bottom sediments, and soils of the region. American chemical companies
were attracted by hydroelectric power generated from the Niagara River
situated near its banks. Canadian chemical companies similarly clustered
along the St. Clair River. Waste sites along the U.S. side of the
Niagara have been a source of contamination to Lake Ontario. Since the
inception of the Superfund program, cleanup efforts have focused on
these sites, substantially reducing their loadings to the Niagara River.
In addition, metals-based industries have been a significant source
of pollutants. Many presently used steel-making technologies generate
byproducts, including ammonia, cyanide, coal tar, zinc, lead and a range
of air pollutants, including fly ash, sulfur compounds, and the volatile
chemicals benzene toluene, and xylene. Steel mills emit benzo(a)pyrene,
the most toxic member of the family of polyaromatic hydrocarbons (PAHs).
Like other PAHs, benzo(a)pyrene is produced by incomplete combustion of
fossil fuels and is suspected of causing lip and liver tumors in
bottom-dwelling fish. PAHs are common in bottom sediments of the Great
Lakes.
In addition, this chapter has suggested that the changes to the Great
Lakes ecosystem during the last three centuries have been vast and that
a long-term perspective is useful to appreciate the magnitude of damage
to once abundant fish and wildlife populations. The next chapter
discusses current challenges facing the Great Lakes ecosystem that are
the focus of government programs, discussed later in this report.