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Our Great Lake With about one fifth of all the world's surface fresh water, the Great Lakes are a natural resource of global significance. (Think about that for a moment: global significance.) In Northeast Ohio, our Great Lake Erie shapes our weather, provides a constant source of drinking water, as well as massive amounts of process and cooling water for industry and power generation. The lake is a vast recreational asset, a magnet for tourism and sport fishing. It is the dominant feature of our geography. But it also is a very vulnerable, troubled lake. It's vulnerable because it has the smallest water volume of all the Great Lakes but the greatest pressures from human settlement. The Lake Erie Basin has more urban area, more heavy industry, higher population densities and more row crop agriculture. It receives larger loads of many pollutants than any other Great Lake. Lake Erie is troubled because its ecosystem is in constant turmoil. In addition to dramatic water quality changes in the past century, the composition of plant and animal species in the lake has fluctuated wildly. Whole species of fish, such as sturgeon and northern pike, have been virtually eliminated by over fishing, pollution and habitat destruction. And nonnative species like the zebra mussel have fundamentally altered the base of the food chain by filtering most of the floating plant matter out of the water column. Thus, although the lake is by no means "dead," it is highly unstable and fragile. Challenges Here are some of the major issues facing Lake Erie today: Conventional pollution. Thanks to hundreds of millions of dollars invested in treatment plants since the passage of the Clean Water Act in 1972, we made a lot of progress controlling conventional pollutionmunicipal sewage, oil, grease, ammonia and the industrial discharges which caused visible water quality problems in the lake. A major problem used to be high phosphorus levels from sewage, detergents and agricultural fertilizers. The phosphorus enriched the lake and caused massive algal blooms, which then turned the lake water into a smelly, brown-green soup of decomposing algae and consumed all the oxygen in the water so fish couldn't survive. People said the lake was dead, but is was really too much alivechoking on an overgrowth of plant matter. Now, improved sewage treatment and a ban on phosphorus in detergent in the Ohio Lake Erie Basin have reduced phosphorus loadings 90 percent from a peak in 1968. As a result, algal blooms are rare and the lake is much clearer (also as a result of zebra mussels). Oxygen levels have increased to the point where mayflies, which dwell on the lake bottom during most of their life cycle, have returned to the lake. Scientists are even worrying that now the lake might not have enough nutrients, although there is a concern about rising nitrate levels from agricultural runoff. Toxics. Persistent toxic substances are the invisible pollution threat to the Great Lakes. Even with the best pollution controls, toxic metals (such as lead, mercury, cadmium), pesticides and chlorinated substances like PCBs continue to enter the lake from a variety of sources. Some of these substances persist in the environment for many months or years and accumulate in the food chain, reaching harmful concentrations in predator species. That is why Lake Erie anglers are advised not to each too much of certain fish. There is growing concern that extremely low concentrations of the chlorinated organic compounds can mimic hormones and interfere in subtle ways with reproduction, development, the immune system and the nervous system. Since conventional end-of-pipe pollution controls cannot prevent the release of these substances into the environment, their use must be eliminated by changing industrial practices. That is why environmental groups and many scientists are calling for an end to the use of chlorine in plastics, solvents, paper production and other industrial processes. Pollution prevention programs are helping industry change over to clean production methods. Air pollution also must be curtailed, as a large proportion of certain toxic chemicals come from emissions from coal-fired power plants or are carried to the Great Lakes from hundreds of miles away. An indicator of success on the toxics issue will be the reproductive success of bald eagles, which have established nests near the western basin of the lake in recent years. Urban runoff and sewer overflows. Water pollution doesn't just come from discharge pipes but also from many diffuse, "nonpoint" sources. Every time it rains, a witch's Agricultural runoff. In recent years environmental regulators have been paying more attention to the environmental impact of agriculture. As pollutant loadings from industry and sewage treatment plants have been reduced, the runoff from farm fields has loomed larger as a source of pollution. When rain washes off fields, it carries soil, fertilizer and pesticides. The sediment clogs streams, destroys fish habitat, and increases dredging costs. Fertilizer overly enriches streams and the lake. And pesticides can accumulate in the food chain. Of all the rivers flowing into the Great Lakes, the Maumee flowing into Lake Erie carries the largest amount of sediment and other agricultural pollutants. In response, Ohio EPA is working with local Soil & Water Conservation Districts and farm organizations to promote conservation tillage methods, buffer strips and other erosion prevention programs in the watersheds of Lake Erie tributaries. Exotic species. Incredible havoc in the Lake Erie ecosystem has been caused by exotic (nonnative) species that have hitchhiked to the Great Lakes in the ballast water of ocean-going ships. One notorious example is the zebra mussel, a thumbnail-sized mollusk imported from Eastern Europe. In just a few years, dense colonies of zebra mussels spread throughout the Lake Erie basin, clogging water intakes and smothering native mollusks (many of which were already endangered species). The filter-feeding zebra mussels are also credited with making the lake remarkable clear in recent years, but they vacuum up the food needed by fish. Other newly introduced species, such as the Eurasian ruffe, may cause more unpredictable changes in the lake's delicate balance of life. In addition, invasive exotic plants, such as purple loosestrife and phragmites (tall reed grass) are destroying native plant diversity in the lake's shoreline marshes while providing little food for wildlife. Lake levels and erosion. Different interests fight fierce battles over manipulating the water level of Lake Erie. Lakefront residents generally favor low water that does not erode their property. Shipping interests want high water so boats can carry more cargo through shallow channels. Marina operators want a stable level so they can build docks that don't become swamped or left high and dry. People interested in the ecology of the lake, however, believe that the lake and surrounding wetlands are dynamic systems that need naturally fluctuating water levels. A study several years ago by the International Joint Commission, the U.S./Canadian agency that monitors Great Lakes issues, found that building structures to control water levels in the Great Lakes would cost billions of dollars and would indeed harm the environment. The best solution is for humans to develop in ways that are adaptable to the lake, not to control the lake for our short-term convenience. Shoreline development. More than 80 percent of Ohio's Lake Erie shore is developed, and much of the rest is under pressure. Only fragments of the lake's once extensive marshesvital habitat for fish and other wildlife-are still intact. And development increasingly encroaches on the rivers flowing into the lake. While such development often is seen as economic growth, it also limits public access to the shore, destroys habitat and increases polluted runoff. In recent years, Ohio has developed a Coastal Management Program to encourage wise use of the Lake Erie coastal area. The program addresses development in the lake's erosion area, the granting of leases to use submerged land under the lake, and other management issues. Other organizations are encouraging municipalities to require that new development be set back from riverbanks and wetlands. Strong citizen activism is needed to protect the lake from damaging encroachment. Water diversions. As unsustainable development in the parched Southwest creates water shortages, we will likely be confronted again with schemes to divert Great Lakes water. Aside from the enormous cost of pipes or canals, such diversions could damage the Great Lakes ecosystem and take away a competitive advantage of abundant water. According to federal law, all of the eight Great Lakes governors must grant approval for new or increased diversions of water out of the Great Lakes Basin. This issue bears close watching as the political pressure for diversions mounts in the future. Nuclear power plants. A major accident at one of the three nuclear power plants on the shores of Lake Erie could contaminate the drinking water of millions of people for many years. The reactors are also having difficulty disposing of radioactive waste and are beginning to store spent fuel in "temporary" casks on site. If there is a worst-case scenario for the lake, it could very well involve these nuclear plants. The threat has been magnified recently by the increased risk of terrorism. Climate change. A longer-term threat to Lake Erie is global warming from the production of greenhouse gases, such as carbon dioxide. If the Earth's temperature increases 1.5 to 4.5 degrees centigrade by the year 2030, here are some possible impacts: Greater evaporation and transpiration rates will reduce water supply in the Great Lakes Basin by 23-51 percent, with Lake Erie losing about 10 percent. Less water will mean greater competition between agricultural, industrial and urban users. Water quality will decline, as there will be less water volume to dilute pollution. Pressure for water diversions from the Great Lakes and Canada's James Bay to the arid Southwest will increase, abetted by free trade agreements like NAFTA. The mean lake level of Lake Erie will fall about 4 to 5 feet. This will leave marinas high and dry and increase costs of shipping and dredging. Contaminated sediments along the shore will be exposed. Coastal wetlands will be at risk, especially if they are enclosed by dikes and can't migrate lakeward as water levels change. Shoreline erosion will be reduced, but that will bring the danger of increased development along the newly exposed shore (developments that will be in danger if lake levels rise again). In addition, Lake Erie will turn over (exchange cold bottom water and warm top water) less frequently, if at all. This could cause the bottom of the lake to become so devoid of oxygen and nutrients that no fish could live there. The ecological impacts could be catastrophic.
EcoCity Cleveland |
Coastal management Lake Erie Balanced Growth Program Cimate change impacts on the Great Lakes Back to main Watershed Planning
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brew of pollutants washes off city streets into storm sewers and then into lakes and streams. In older urban areas, storm and sanitary sewers are combined in one pipe, so raw sewage can overflow into the environment along with the urban runoff. One immediate human health concern is the high bacteria levels contained in this runoff. For a couple of days after heavy rains many urban rivers and Lake Erie beaches become unsafe for swimming. Correcting urban runoff problems will require everything from better street sweeping to costly construction projects to contain sewer overflows.