Polluted stormwater runoff can have many adverse effects on plants, fish, animals, and people.
Bacteria and other pathogens can wash into swimming areas and create health hazards, often making beach closures necessary.
Debris - plastic bags, six-pack rings, bottles and cigarette butts - washed into water bodies can choke, suffocate or disable aquatic life like ducks, fish, turtles and birds.
Excess nutrients can cause algae blooms. When algae die, they sink to the bottom and decompose in a process that removes oxygen from the water. Fish and other aquatic organisms can't exist in water with low dissolved oxygen levels.
Household hazardous wastes like insecticides, pesticides, paint, solvents, used motor oil, batteries and other auto fluids can poison aquatic life. Land animals and people can become sick or die from eating diseased fish and shellfish or ingesting polluted water.
Polluted stormwater often affect drinking water sources. This, in turn, can affect human health and increase drinking-water treatment costs.
Sediments can cloud the water and make it difficult or impossible for aquatic plants to grow. Sediment also can destroy aquatic habitats.