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• Chapter Four - The Great Lakes Today - Concerns

 

 

THE GREAT LAKES TODAY: CONCERNS

FOUR

Wilderness is the raw material out of which man has hammered the artifact called civilization ... No living man will see again the virgin pineries of the Lake states, or the flatwoods of the coastal plain, or the giant hardwoods ...

- Aldo Leopold

Distribution of Population (135 GIF)

While parts of the Great Lakes ecosystem have been changed to better suit the needs of humans, the unexpected consequences of many of the changes have only recently become apparent. Since about 1960, there has been an awakening to the magnitude of these changes and the harsher implications of some human activities. The largest categories of impact are pollution, habitat loss and exotic species.

Modern, large-scale agriculture, with its reliance on synthetic fertilizers and pesticides, is one of the main nonpoint sources of pollution to the Great Lakes. (Great Lakes Program Office, U.S. EPA, Chicago, Illinois.)

Deterioration in water quality and habitat began with modern settlement. At first the impact was localized. Agricultural development, forestry and urbanization caused streams and shoreline marshes to silt up and harbor areas to become septic. Domestic and industrial waste discharges, oil and chemical spills and the effects of mining left some parts of the waterways unfit for water supply and recreation. Waste-treatment solutions were adopted to treat biological pollutants that threatened the immediate health of populations. In some jurisdictions, regulations were passed to prevent capricious dumping in the waterways. Eventually, however, it took a major threat to the whole Great Lakes basin to awaken authorities to the fact that the entire Great Lakes ecosystem was being damaged.

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 feces 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.

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 settlement 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 that 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 harbors 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 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 owing, 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 that 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,

 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.

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Toxic Contaminants

Sign on the Grand Calumet River, Indiana.  (Lake Michigan Federation, Chicago, Illinois.)

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.

The carcinogenic effects of toxic pollutants are believed to have caused this tumor (ossifying fibroma) on a sauger from the Great Lakes. (Great Lakes Program Office, U.S. EPA, Chicago, Illinois.)

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.

The crossed bill of this Cormorant is believed to be an effect of toxic contamination of the food chain in isolated locations on the lakes. (Great Lakes Program Office, U.S. EPA, Chicago, Illinois.)

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 estrogen, 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 estrogen, 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 estrogen-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.

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Pathways Of Pollution

While efforts were underway to reduce point sources of pollution and to study nonpoint pollution sources, it was discovered that many pollutants are deposited from the atmosphere. Like the precursors of acid rain, which can originate far from where the damage occurs, nutrients and toxic contaminants can be carried long distances from their sources to be deposited in the lakes in wet and dry forms. Atmospheric deposition of a pollutant in the Great Lakes basin was first recognized with phosphorus. Measurements of rain, snow and dust fall showed that about 20 percent of the phosphorus loading to Lake Michigan was from the atmosphere. Because this source could not be controlled, the need to reduce phosphorus in detergents, in sewage treatment and from fertilizer runoff was reinforced. Atmospheric deposition of toxic chemicals was recognized by measurements of PCBs in precipitation after these chemicals were discovered in Great Lakes fish in 1971. Long-range transportation of substances was confirmed by the PCBs and toxaphene discovered in fish from a lake on Isle Royale, a remote island in Lake Superior isolated from any known direct sources of the pollutants.

Transport of substances such as PCBs is complicated by the fact that they tend not to stay dissolved in water and thus volatilize back into the atmosphere or become attached to particles. As a result, large quantities of PCBs volatilize out of the lakes, as well as being deposited into them from the vast reservoir of synthetic organic chemicals moving about in regional and global air masses.

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 harbors 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 harbors, 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.

Sediment Resuspension. Polluted sediments that have settled out of the water can be stirred up and resuspended in water by dredging, by the passage of ships in navigation channels, and by wind and wave action. Sediments can also be disturbed by fish and other organisms that feed on the bottom.

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.

Loadings To A Closed System

In considering pathways of pollution, it is important to recognize that in the case of the Great Lakes, unlike rivers that run to the oceans, pathways end in the lakes. Regardless of whether pollutants are diluted by large stream flows or temporarily stored on sediment particles on stream bottoms, they will eventually reach the lakes and add to the total burden.

Because the lakes respond to total quantities of persistent substances as well as localized concentrations, it is important to understand the total loading of pollutants to each lake from all pathways. This was first recognized for phosphorus, as reflected in the Great Lakes Water Quality Agreement.

As laboratory capability for analysis has improved together with the understanding of how persistent toxic substances cycle in the ecosystem, total loadings are becoming known. This knowledge, together with bioaccumulation factors, can translate loadings into predictable levels in biota. These developments hold the promise that the Lakewide Management Plans called for in the Agreement can provide the 'schedule of load reductions of Critical Pollutants that would result in meeting Agreement Objectives.

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Control Of Pollutants

As major progress has been made in control of industrial and municipal discharges to waterways, the importance of other sources has become better understood.

Direct discharges to waterways are known as point sources. Because such sources have specific owners and can be easily sampled, regulatory programs have resulted in a high degree of control. Nonpoint sources include urban and agricultural runoff, airborne deposition of pollutants from automobiles and commercial activities, and contaminated sediments and contaminated groundwater. Control of nonpoint sources is made difficult by their diffuse nature, episodic release and lack of institutional arrangements to support their control.

Because of the myriad of widespread contributors, nonpoint sources are far less suited to regulatory control. As a consequence, public education, pollution prevention and voluntary actions are very important. The importance of pollution prevention is gaining increasing recognition both as an effective means of dealing with nonpoint pollution and in dealing with pollutants from point sources that continue to cause problems even after state-of-the-art treatment has been applied. Pollution prevention focuses on eliminating pollutants before they are produced. This includes changing production processes and feedstocks, and choice of environmentally benign products by consumers.

One preventive approach has been to ban the production/extraction and use of certain individual chemicals and metals and to prevent the direct discharge of others into waterways. The production and use of DDT were banned after it was shown that the pesticide thinned the shells of bird eggs, causing reproductive failures. The levels of DDT in the environment began to decline immediately following regulation. In the case of PCBs, production has been banned but their use is still being phased out.

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.

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 percent in Minnesota to 92 percent 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.

Exotic Species

This shopping cart was left in zebra mussel-infested waters for a few months. The mussels have colonized every available surface on the cart. (J. Lubner, Wisconsin Sea Grant, Milwaukee, Wisconsin.)

An equally important cause of change 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.

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 because of toxic chemicals present in the fish. Advisories are now issued on a regular basis to limit exposure and protect health.

Because of current scientific uncertainty about the toxicity of these chemicals to humans, 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 large quantities 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 persistent contaminants accumulate in fatty 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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Sustainable Development

Pollution prevention, protecting and restoring habitat, protecting biodiversity, understanding the ecosystem and cleaning up old pollution problems are all a part of sustainable development. The term 'sustainable development' first gained visibility in the report of the World Commission on Environment and Development, commonly known as the Bruntland Commission. The report, entitled 'Our Common Future', defined the concept generally as the process of change in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are made consistent with future as well as present needs. If the Parties to the Great Lakes Water Quality Agreement are to fulfill its purpose 'to restore and maintain the chemical, physical and biological integrity of the waters of the Great Lakes Basin Ecosystem' it is clear that attaining sustainable development within both countries is essential.

A major test of whether sustainable development has been achieved will be whether this integrity has been restored or maintained. The concept of integrity of an ecosystem recognizes that ecosystems contain mechanisms that create both stability and resiliency within them. Integrity includes the capacity of the system to remain intact, to self-regulate in the face of internal or external stresses and to evolve toward increasing complexity and integration.

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 (one Area of Concern - Collingwood Harbour - has been cleaned up).

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.

Major Diversion Proposals

A number of proposals have been made for large-scale diversion of water from water-rich regions of North America to water-poor areas experiencing growth in population and industry. The plans generally call for interbasin transfer of Great Lakes water or Canada's Arctic fresh waters southward to the western U.S. Massive engineering schemes needed to do this have often been proposed by private entrepreneurs interested in selling the water or benefiting from improved water supply to their area.

In the l960s, a California engineering firm proposed a 'North American Water and Power Alliance' (NAWAPA). The plan included diversion of water from Alaska and northwestern Canada through a major valley in the Canadian Rockies (Rocky Mountain Trench) for distribution as far as Mexico by a system of canals and rivers. Efforts to revive NAWAPA in the l970s failed. At the direction of the U.S. Congress the U.S. Army Corps of Engineers suggested diversion of water from the Great Lakes via the Mississippi River to compensate for rapid depletion of groundwater from the Ogallala aquifer in the high plains states of Nebraska, Kansas, Oklahoma and Texas. A Colorado proposal called for a canal or a pipeline to carry water from the Great Lakes to rapidly growing economies in the Southwest. Both ideas were opposed by all Great Lakes states and the Province of Ontario.

The Great Recycling and Northern Development (GRAND) Canal concept was revived in l985 after being proposed in the l950s. The plan calls for turning James Bay into a freshwater lake using a dam to prevent mixing with saltwater from Hudson Bay. Fresh water would then be pumped over the Arctic divide and transferred into the Great Lakes. Great Lakes water would in turn be diverted for sale to western states. Development would require an estimated $l00 billion (Canadian) and the support of Ontario and Quebec, all the Great Lakes states as well as the federal governments of both countries.

Invariably the proposals have failed to materialize for economic reasons. Increasingly, however, opposition to these proposals is based on environmental concerns because the environmental impacts of large-scale diversions have not been adequately assessed. In the 1985 Great Lakes Charter all the state governors and the premiers of Ontario and Quebec agreed to cooperate in consideration of any proposed diversion.

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 favorable 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.

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