Soil in runoff carries contaminants that smothers and kills aquatic life. Fertilizers, car exhaust and detergents cause explosive plant and algae growth, which depletes water of oxygen,
killing fish and animals as well as creating a terrible smell. Loose grass clippings and leaves also add to this and clog drainage systems. Pet droppings and septic tank overflows can cause diseases like dysentery, hepatitis and parasite infections by getting into drinking water and recreation areas. Oil, paint, cleaning supplies and other toxic materials from cars and batteries contaminate drinking water and kill fish, animals and plants.