The loss of wetlands in many watersheds has reduced the ability of nature to process these nutrients before they enter rivers, streams, and ultimately estuaries. When the algae die off, the decaying process uses up the oxygen in the water, leaving little, if any, for fish and other aquatic organisms. Toxic substances , such as pesticides from lawns, gardens, and farms, and lead, oils, and greases deposited on roads from cars and trucks, can all run off the land with rainfall and snowmelt. Industrial plants and municipal wastewater treatment plants can also contribute to the amount of toxic substances entering streams and rivers and ultimately lakes, estuaries, and coastal waters. Fish kills and loss of the recreational uses of an area can occur.
Pathogens are microscopic organisms like bacteria and viruses.
They come from untreated or poorly treated sewage, pet and farm animal waste, and improperly handled medical waste. Pathogens in the water in unsafe amounts result in beach closures, shellfish bed closures, fish kills, and human health problems. Resource Impacts Activities in the watershed can adversely affect a variety of resources. Along with bays and estuaries, nearshore waters are collection places for pollutants that flow from the watershed. What happens in one part of the watershed can affect another part, sometimes hundreds of miles away.