This major water quality problem is known as polluted runoff the phenomenon in which pollutants on agricultural fields, city streets, and suburban lawns are carried into rivers, lakes, and coastal waters by runoff from rain or snow.
Polluted runoff comes in various forms and causes a series of problems.
Soil sediment from sources such as plowed fields and construction sites can destroy fish habitat and kill aquatic life. Pesticides swept from fields and lawns into water bodies can increase the risks of cancer and birth defects in human beings. Excess nutrients, such as nitrogen and phosphorus from fertilizers applied to lawns and crops, feed algae blooms that can prevent people from swimming and can kill fish and other aquatic life by robbing the water of oxygen. Heavy metals such as lead and copper, which can come from mining and industrial processes, along with bacteria and pathogens from various sources also make their way into waterways through polluted runoff where they can cause a variety of human health problems. Wetlands are a vital line of defense in protecting water quality from polluted runoff.