14,000-9,000 years ago

The glaciers of the last ice age retreat from what is now the Great Lakes basin. 

8,000-9,000 years ago

The region is settled by humans, who follow the retreating glaciers. The water level of the lakes is about 100 metres higher than now.

In the period before contact with Europeans in the 1600s the aboriginal population of the Great Lakes basin is between 60,000 and 117,000. 

The 1600s

While seeking a route to the Orient, French explorers arrive at the Great Lakes. At first they take the vast expanses of water for the Pacific Ocean, until they taste the water. They call the lakes Sweetwater Seas. The first such explorer is likely Étienne Brûlé who, guided by Huron Indians, paddles into Georgian Bay. In 1634 and 1669, French explorers Jean Nicollet and Louis Jolliet reach Lakes Michigan and Erie.

1800

About 300,000 people live around the Great Lakes, mainly around Lakes Ontario and Erie. 

View of Erie Canal by John William Hill, 1829.

1825

The Erie Canal opens, linking Lake Erie at Buffalo with Troy on the Hudson River nearly 600 km away, and allow a connection to the Atlantic Ocean. This is the first significant canal allowing direct water access past natural barriers of the Lachine Rapids and Niagara Falls.

1829

The Welland Canal opens, allowing ships to bypass the natural barrier of Niagara Falls, more than 50 metres high. Three more canal projects were to deepen and widen the passage, allowing both ocean-going boats and non-native species such as the sea lamprey to reach the upper lakes.

1848

The Illinois and Michigan ship canal is built at Chicago to enable boats to sail between the Great Lakes and the Illinois River, which connects to the Mississippi. This becomes known as the Chicago Diversion. 

1854

A cholera epidemic caused by contaminated water kills five per cent of Chicago’s population. This is one example of the toll of typhoid and cholera caused by increasing amounts of untreated human sewage entering the drinking water not only in Chicago but wherever development was exceeding the capacity of the water to safely dilute human wastes. 

1870s

Hamilton Harbour is so contaminated that water is undrinkable. A steam-driven pump is installed to bring water from Lake Ontario. This is a story that will be repeated around the basin as people keep trying to put water intakes beyond the reach of their own waste discharges.

1891

A typhoid epidemic in Chicago caused by contaminated water leads to a move to deepen the canal to carry wastes away from the drinking water intake.

1896

Last Atlantic salmon reported in Lake Ontario.

1900

The Great Lakes population reaches 11.5 million.

The Chicago Diversion is enlarged and renamed the Chicago Sanitary and Ship Canal. The canal is deepened to the point that it reverses flow of the Chicago River from Lake Michigan and water pours out of the lake to reach the Des Plaines, Illinois and Mississippi rivers and eventually the Gulf of Mexico. It allows more ship traffic, and it flushes Chicago’s sewage down the river and away from Lake Michigan, its source of drinking water. This leads to a long-running dispute over how much water should flow through the canal.

1905

An International Waterways Commission is formed by Canada and the United States to advise governments on levels and flows in Great Lakes. It functions from 1905-1913, with some work continuing to 1919. It recommends a treaty on waters and a permanent body.

1908

Since the late 1800s, chlorination is proposed then tested as a way of disinfecting drinking water. By now it is being used in a number of drinking water treatment plants in the United States. By 1910, Toronto starts to chlorinate its drinking water. This period marks the widespread use of drinking water chlorination, a process that is to save untold numbers from disease and death.

1909

The United States and Great Britain on behalf of Canada, sign the Boundary Waters Treaty a historic agreement on the sharing of common waters, aimed at eliminating disputes. The agreement contains a prescient clause: “Boundary waters and waters flowing across the boundary shall not be polluted on either side to the injury of health or property on the other.” 

The agreement creates a six-member International Joint Commission, with three members each appointed by the U.S. president and Canada’s prime minister. The first commission is named in 1911, and starts meetings early in 1912. It is asked by the two countries to identify the extent and sources of pollution of the Detroit and Niagara Rivers.

1918

The first report on Great Lakes water quality is issued by the International Joint Commission on the Pollution of Boundary Waters Reference. The report states that the “…situation along the frontier is generally chaotic, everywhere perilous and in some cases, disgraceful.”

1925

The U.S. Government challenges the right of Chicago to divert Lake Michigan water without consulting its neighbors. The other Great Lake states, with support from Canada, allege potential economic losses in a series of subsequent lawsuits. The suits lead to U.S. Supreme Court decrees in 1930 and 1967, with an amendment in 1980. The court allows the diversion to continue, but cuts its flow from a high of 280 cubic metres per second down to 90.

1930

The Great Lakes basin population is close to 23 million, an increase of 30 percent in 20 years.

1931

A burning oil slick on lower Don River in Toronto severely damages a steel and wooden pedestrian bridge and is hot enough to buckle steel rails.

Sea lamprey on host fish

1930s and 1940s

The sea lamprey, an eel-like primitive, jawless fish native to the Atlantic, moves into Lakes Huron, Michigan and Superior, devastating commercial fisheries, particularly for Lake Trout.

The 1940s

Demands for chemicals, rubber, steel, nuclear weapons and other materials in support of the Allied effort in the Second World War lead to a major industrial expansion in the Great Lakes basin. This period marks the start of large-scale chemical and heavy metal discharges to the lakes. The heaviest pollution appears to have been in the 1960s and 1970s, then tapers off.

1946

The International Joint Commission is asked by the two nations to investigate pollution on St. Clair River, Lake St. Clair and the Detroit River. That reference is later extended to include the St. Marys River.

1949

The Supreme Court of Canada orders a pulp and paper company in Espanola, Ontario to stop polluting the Spanish River, because that violated the rights of fishermen and a tourist operator who had sued. The Ontario Government passes legislation allowing the pulp mill to continue to pollute the water.

The 1950s

The “dying” of Lake Erie becomes one of the biggest environmental stories in North America. In fact, the lake is being over fertilized by phosphorus, particularly from sewage and detergents. This causes excessive growth of algae, and when they die, their decomposition sucks oxygen out of the water, killing life in certain parts of the lake. At one point, this process chokes off oxygen to 65 per cent of the lake bottom. 

Starting in the mid-1950s, scientists note reproductive failures in fish-eating birds, including the almost total reproductive failure of some species, such as double‑crested cormorants, bald eagles and herring gulls in Lake Ontario. This is later attributed to toxic chemicals including the widely used insecticide, DDT.

1950

Report of the International Joint Commission on the Pollution of Boundary Waters Reference from 1946. It reports major concern over the amount of bacteria plus phenols, oil, iron, phosphorus, chloride and discoloration in the Niagara River. The report recognizes that sewage treatment has not kept up with population growth. The IJC finds injury to health and property from municipal and industrial wastes and shipping.

1952

Canada and the United States sign an agreement to start the St. Lawrence Seaway project, which will open up the lakes to ocean ships.

1955

The municipality of Richmond Hill, north of Toronto, is sued by a downstream resident for polluting the Don River with sewage and the resident wins in court. Ontario passes legislation overturning this decision and a similar one involving Woodstock. 

Canada and the United States sign the Great Lakes Fishery Convention, which leads to the formation of Great Lakes Fishery Commission. One of its major issues is control of the sea lamprey.

1956

St. Lawrence Seaway

The Ontario Water Resources Commission, the first agency of its kind, is created to deal with sewage issues and drinking water treatment needs.

1959

Opening of the St. Lawrence Seaway, with its deep, wide canals, allows ocean-going freighters access to the lakes. This also allows the more widespread introduction of exotic or alien species, which hitchhike rides in the ballast water picked up in foreign ports. 

DDT is detected in the Lake Erie ecosystem. 

This is a major period of economic expansion, leading to large-scale discharge of chemical wastes into the lakes. Persistent toxic substances begin to accumulate in the food chain. It is also a period when public concern about the environment becomes a major force in society. This begins the process of a long turnaround from increasing to decreasing discharges of pollutants into the environment. One of the early successes is the move to reduce phosphorus pollution, particularly in Lakes Erie and Ontario. 

Rachel Carson, author of Silent Spring

1962

The publication of Silent Spring by Rachel Carson is a major trigger point in the development of the modern environmental movement. The book raises concerns about risks from chemicals and pollution for the environment and human health.

1964

Canada and the United States ask the International Joint Commission to investigate the deteriorating state of Lakes Erie, Ontario and the international section of the St. Lawrence River.

1965

The International Joint Commission recommends action to reduce phosphorus, particularly by improving sewage treatment.

Mink breeders in Michigan note reproductive failures in animals fed Great Lakes fish.

1966

A federal water administration is created in Canada’s Department of Energy Mines and Resources.

The Cuyahoga River on fire

1969

The oily surface of the Cuyahoga River in downtown Cleveland catches fire, and a fireboat is called in to battle the blaze. The river surface had previously caught fire in 1936 and 1952, but the 1969 incident provokes international coverage and helps to focus attention on the need to tackle the gross pollution still being discharged into the Great Lakes. It is influential in debates leading to the U.S. Clean Water Act, the creation of the U.S. Environmental Protection Agency and the 1972 binational Great Lakes Water Quality Agreement.

Pollution Probe is created in Toronto by a small group of University of Toronto students assisted by some faculty. The organization chooses water pollution, especially that of the Don River, a tributary of Lake Ontario as one of its first issues.

This is a turnaround decade for the Great Lakes. It is a decade of discovery for toxic chemicals in the lakes’ ecosystem, and many people become fearful for their drinking water because of leaking chemical dumps. It is also a decade when the United States and Canada sign two major Great Lakes Water Quality Agreements, pledging efforts that will cost billions of dollars to reduce pollution.

Researchers are finding deformities such as crossed bills, club feet and missing eyes observed in Great Lakes birds that consume large amounts of fish.

By the latter part of the decade, researchers are pointing out the importance of non-point sources of pollution, including runoff from pollution on the land agricultural and airborne chemical fallout.

1970

By 1970, the Great Lakes basin population reaches nearly 31 million, an increase of 36 percent over 20 years.

The announcement that mercury has contaminated fish in Lake St. Clair and Lake Erie triggers the first major crisis of confidence in Great Lakes fish. Mercury, a heavy metal, can cause nerve damage. The discovery that it has penetrated the food chain leads to large-scale fisheries closures in the region.

During the following decade, scientists find a number of dangerous chemicals in Great Lakes fish and wildlife, including polychlorinated biphenyls (PCBs), a widely used insulating fluid and the insecticides Mirex, Lindane, Aldrin, Endrin, Chlordane and Heptachlor. This leads to extensive warnings about the hazards of eating fish from the lakes.

The United States creates the Environmental Protection Agency.

1971

Canada creates a Department of the Environment.

The International Joint Commission report on pollution of the lower Great Lakes leads to negotiations between Canada and the United States on a Great Lakes Water Quality Agreement.

The first Canada-Ontario Agreement Respecting Great Lakes Water Quality pledges the two levels of government to co-ordinate their actions to protect the lakes.

Fish consumption warnings are issued for Lake Michigan trout because of PCBs in the fish. This follows studies showing that ranch mink raised on such fish suffer reproductive problems.

The company manufacturing PCBs voluntarily limits production, and stops it entirely in 1978. However, many tonnes remain in use, mainly in electrical equipment, and PCBs escape into the environment through accidents and mishandling.

1972

Canada and United States sign the first Great Lakes Water Quality Agreement, which aims to control sewage and phosphorus discharges. This leads to severe restrictions on phosphates in detergents, and to billions of dollars of investments in sewage treatments. The 1972 agreement also raises toxic substances as a major concern.

Ontario creates an environment ministry, which incorporates activities of the Ontario Water Resources Commission.

1976

Love Canal becomes the biggest pollution story in North America. Chemicals seeped from an old toxic waste dump in Niagara Falls, N.Y. into neighborhood basements, and bubbled up onto the ground beside the elementary school. The chemicals also drain into the Niagara River and thus into Lake Ontario. In subsequent years, millions of people downstream fear for the safety of their drinking water because of concerns about chemicals leaking from Love Canal and more than 150 other chemical dumps along the Niagara River.

1978

Canada and United States sign the second Great Lakes Water Quality Agreement, introducing the concept of protecting the entire ecosystem of the lakes, the philosophy of zero discharge of persistent toxic substances to the lakes and the policy of the virtual elimination of inputs of persistent toxic substances.

The Pollution from Land Use Activities Reference Group [PLUARG] report focuses attention on the growing importance of non-point sources of pollution, largely from runoff from agricultural and urban wastes.

Protest by residents of Love Canal

The International Joint Commission’s Water Quality Board releases a list of 500 organic or heavy metal contaminants in the air, water land and living creatures of the Great Lakes basin. Scientists would later push that list to over 1,000.

A series of stories point to a health emergency around Love Canal. By spring, state and federal health and environment agencies move in, fencing off the canal itself and testing air and water samples and in August, New York declares a State of Emergency, closes the school and evacuates pregnant women and infants. President Jimmy Carter declares it a federal disaster area, the first time in that country for a disaster created by humans. The governments evacuate 255 families in what is called the “inner ring” of homes nearest the canal. When dioxin, a highly dangerous substance, is found in the Love Canal wastes, more homes are evacuated.

By now about 37 million people live around the Great Lakes, creating one of the world’s major industrial centres, producing a wide array of products, including automobiles, chemicals, petroleum products, steel and hydroelectricity.

During this decade, concern about chemicals in the Great Lakes peaks with a series of scientific discoveries of dangerous pollutants in the ecosystem. Governments make further pledges to control pollution, and Canada and the United States sign a major update to the previous Great Lakes Water Quality Agreements. Industries, under growing criticism for their environmental performance, begin to not just react to regulations but to show leadership in pollution prevention. The Canadian Chemical Producers Association launches the Responsible Care program, which is later picked up by chemical industry groups around the world.

Researchers studying infants whose mothers ate significant amounts of contaminated Great Lakes fish were born smaller and suffered neurological problems.

During the decade, scientists are measuring significant declines in the levels of many dangerous chemicals in birds and fish and improved reproductive success in some birds.

Great Lakes water levels become a major issue late in the decade, as they reach the highest point in the century. This causes extensive flooding and damage to homes and buildings constructed during lower water levels. There are calls for governments to control the lakes, but a study says that major controls are impractical.

The concept of sustainable development is introduced into the environmental debate by the 1987 report of the Brundtland Commission. It provides a way for governments, industries and some non-government organizations to enter a debate on common environmental goals. Some of the most active industries in the debate come from the Great Lakes basin.

1980

A scientist announces that dioxin has been found in herring gull eggs from around the Great Lakes, particularly Lake Ontario.

1981

Pollution Probe issues a report, Toxics on Tap, which says there are 16 suspect chemicals in Toronto’s drinking water, and they pose a health hazard.

1982

The International Joint Commission identifies 39 contaminated Areas of Concern around the Great Lakes, where environmental agency guidelines are being exceeded. [This list is expanded to 42 in 1985.]

Great Lakes United, a binational organization that includes a wide array of people and organizations, is created as a watchdog on lakes issues.

1983

Pollution Probe issues a second report called, Drinking Water: Make It Safe, which creates a new controversy by predicting that between 72 and 156 Toronto residents would get cancer in their lifetimes because of pollution in their drinking water.

New targets set for phosphorus discharges to Lakes Erie and Ontario.

1984

The Toronto Board of Health releases a report saying that although trace amounts of 83 chemicals have been found in Toronto drinking water at one time or another during the past decade, the levels were low enough that, “Residents of Toronto can drink tap water with reasonable assurance it is not likely to cause harm or injury.”

Canada and the United States release the most comprehensive report yet on the state of the Niagara River listing 261 chemicals of concern in the river, its bottom mud and wildlife.

1985

Concerns about the possibility of water diversions from the Great Lakes to dry southern parts of the United States prompt the eight Great Lakes states, Minnesota, Michigan, Wisconsin, Illinois, Ohio, New York, Pennsylvania and Indiana, along with Ontario and Quebec, to sign an anti-diversions agreement called the Great Lakes Charter.

The discovery of a “blob” of perchloroethylene (dry cleaning fluid) on the bottom of the St. Clair River as result of spill from the Dow Chemical Canada Inc. plant in Sarnia raises fears of toxic chemicals in that region, known as Canada’s chemical valley. Following that incident, Dow promises to virtually eliminate spills and discharges to the river, and begins a major project to stop discharges, spills or leaks to the river.

Scientists calculate that more than 3,000 tonnes a year of chemical wastes flow down the Niagara River every year.

A senior Toronto alderman proposes a drinking water pipeline from Georgian Bay, 180 km away. This is one of a number of proposed or actual pipelines used to bypass contaminated areas of the Great Lakes.

Canada’s federal water policy report is released.

1986

Governors of the Great Lakes states sign the Great Lakes Toxic Substances Control Agreement promising to reduce toxic discharges to the maximum extent possible. Later, Ontario and Quebec sign a memorandum of understanding, which joins them to the agreement.

1987

A Declaration of Intent on Pollution of Niagara River commits the governments of Canada, United States, Ontario and New York, to reduce certain toxic discharges to the river by at least half by 1996.

Zebra mussels infest a water intake pipe

Canada and the United States sign a Protocol to the Great Lakes Water Quality Agreement. One aim is to deal with the more than 300 contaminants now clearly identified in the Great Lakes ecosystem, including the water, sediments, fish, animals, waterfowl and humans. The Protocol also covers such issues as airborne pollution that falls on the lakes, leaking dumps and polluted runoff. The two nations agree to develop Remedial Action Plans to bring business people and citizens into the process of helping to clean up contaminated Areas of Concern around the lakes.

Zebra mussels, an exotic species that likely arrived in the ballast water of an ocean-going ship, are discovered in the Great Lakes. Although only one of about 140 alien species introduced to the lakes since records began in 1810, the mussel attracts a great deal of attention to the issue.

1988

A severe drought affects the U.S. mid-west, and the Mississippi River drops to its lowest recorded levels. The Illinois governor calls for the Chicago diversion to be further opened to draw more water Great Lakes, via Chicago on an emergency basis. This provokes strong opposition around the lakes. 

During this decade, governments, industries and non-government organizations enter a more collaborative approach to dealing with water pollution issues. It is a period of further controls to industrial discharges and the development of Remedial Action Plans to deal with contaminated sites. The populations of some native lakes species are increasing, but there are more reports of exotic species entering the lakes, likely in the ballast waters of ocean-going ships.

By the mid-1990s budget cuts by governments in both Canada and the United States are reducing the ability of environment departments to carry out programs or even to monitor the state of the lakes as effectively.

1990

By 1990, the Great Lakes basin population is more than 33 million, 8 per cent more than in 1970.

The International Joint Commission reports to governments that despite declines in the levels of persistent toxic chemicals in the Great Lakes  ecosystem, they are still high enough to pose a threat to human health, particularly to children.

The IJC and the Great Lakes Fisheries Commission prepare a joint report on the risk of alien invasive species, which are having an ever-great impact on the lakes’ ecosystems.

1991

7:08 am, June 27, 2001: a thick brown  blanket of smog hangs over Toronto

Canada introduces strict new pulp and paper regulations that say mills must not release measurable amounts of dioxins and furans by 1994. Mills must also greatly reduce discharges of other harmful organochlorine chemicals and other pollutants, including those that poison fish or cause oxygen starvation.

The Canada-United States Air Quality Accord calls for reductions in a range of air pollutants, including those contributing to smog across the lower Great Lakes.

Canada, the United States, Ontario, Michigan, Minnesota and Wisconsin agree to establish A Binational Program to Restore and Protect the Lake Superior Basin.

1992

The International Joint Commission recommends that Canada and the United States, in consultation with industry and other affected interests, develop timetables to sunset the use of chlorine and chlorine-containing compounds as industrial feedstocks. This provokes an intense debate and strong criticism of the commission by some industry spokespeople.

1993

Flooding introduces cryptosporidium, a protozoan parasite, into the drinking water system of Milwaukee, Wisconsin. The outbreak affects about 400,000, hospitalizes 4,000 and kills 111. [A smaller outbreak in Collingwood, Ontario in 1996, sickens a number of people.]

A report from the International Joint Commission says that governments need to do more to protect human health from toxic chemicals in the Great lakes, especially those that cause reproductive problems.

1994

Collingwood Harbour on Georgian Bay is the first Area of Concern to be declared restored and is de-listed.

1997

Canada and the United States sign the Great Lakes Binational Toxics Strategy. The goal is to build collaboration among all major groups around the basin, including all levels of government, native peoples and business to work for the virtual elimination of persistent toxic substances resulting from human activity.

After more than two centuries of intense human intervention, the Great Lakes ecosystem is dramatically different. Most of the natural forests have been cut at least once, but some areas, unsuitable for agriculture, have been replanted with trees or allowed to regrow naturally. However, farming has become much more intensive, leading to extensive use of fertilizers, pesticides and other chemicals, and issue of managing large amounts of animal wastes. Major industries have largely controlled discharges to the lakes, but most small and medium-sized businesses do not have sophisticated waste management systems. The basin remains a magnet for humans, and an expanding population is leading to urban sprawl that is removing natural habitat and creating more dispersed sources of runoff that reaches the Great Lakes.

There have been very important reductions in the discharges of dangerous chemicals into the lakes. Both countries have made great strides in destroying PCBs. They have virtually eliminated the use of lead in gasoline, banned a number of very harmful pesticides, and cut industrial and municipal waste discharges. One very difficult issue to still resolve is that of contaminated sediments in the bottoms of industrial harbours and rivers, a legacy of former unregulated discharges. Another is airborne fallout, some of it from faraway sources.

As a result of the reductions in releases of persistent toxic substances that bio-accumulate in the food chain, some species, such as the herring gull, double-crested cormorant and the bald eagle, are making a comeback in the lower Great Lakes. The levels of toxic substances in sport fish have declined sharply in most areas, reducing the risk to people who catch and eat them. There are even efforts to reintroduce the Atlantic salmon to the lakes.

2000

Heavy May rainfalls carry e. coli bacteria from farm wastes into a poorly protected drinking water well for the small, rural town of Walkerton, Ontario. The resulting outbreak of illnesses kills seven and leaves more than 2,300 ill.

2001

The United States and Canada release their latest State of the Great Lakes Report. It says that 25 per cent of the 33 indicators showed good or improving trends, 50 per cent were mixed in terms of improvements or declines and 25 per cent were poor or deteriorating.

In June, the governors of the Great Lakes states and premiers of Ontario and Quebec sign Annex 2001, an update to the 1985 Great Lakes Charter, to help clarify policies to keep control of the use of water resources within the basin.

By 2001, water levels in Lakes Huron, Michigan St. Clair and Erie reach lowest levels since mid-1960s.

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