Fecal coliform bacteria are found in the feces of humans and other warm blooded animals. These bacteria can enter lakes and rivers directly or from storm water runoff, agricultural wastes and wastes from birds and mammals, as well as from human waste discharged into the water.Fecal coliform by themselves are not dangerous, but are an indicator of contamination. Fecal coliform bacteria naturally occur in the human digestive tract and aid in the digestive process. In infected people, pathogenic organisms are found along with the fecal coliform.
If a fecal count in swimming water exceeds 200 Colony Forming Units (CFU), the risk increases that pathogenic organisms are also present. A person swimming in water with fecal counts exceeding 200 risk getting sick. Pathogens can enter the body through cuts in the skin or through the nose, mouth, and ears.