While water pollution has many impacts on the environment, its effects are most readily visible in the lakes and streams where pollution kills fish and other aquatic life. According to TEACH Great Lakes, biologists declared Lake Erie a dead lake in the 1960s, yet it was full of life. The problem was that it was the wrong kind of life, which caused a disruption in the lake due to pollution.
Toxic heavy metals are one type of pollution that affects lakes and rivers. Often, heavy metals come from industrial processes, such as the steel mills that once surrounded many of the Great Lakes. These materials are toxic to fish and shellfish, but they have the potential to affect the rest of the food chain, including the animals that live on land as well as those in the water.
Bacteria and other pollutants from sewage affect the health of organisms living in the water as well as those who drink it. Clean drinking water is an issue for many animals.
Without pollution, large natural lakes contain few nutrients for plants, and their temperatures remain cool all year long. They slowly dissolve minerals from the soil and decaying plant matter needed to support adequate plant life for the food chain. Pollution increases the plant nutrients in the water, while industrial waste increases its temperature. As the wrong type of plant growth increases, the oxygen supply decreases. While improving conditions for some species, pollution affects the natural balance and beauty of bodies of water as well as the environment.