Fuel oil, gasoline and kerosene may leak into ground water through damaged storage tanks. Animal Waste Human wastes that are not properly treated at a waste treatment plant before being released to water may contain harmful bacteria and viruses. The main source of this problem is sewage getting into the water. People can come into contact with these microorganisms by drinking the polluted water or through swimming, fishing, or eating shellfish in polluted waters. Often unexpected flooding of barnyards or stock pens can suddenly increase the toxic effects of animal waste in water.
Animal waste can also act as a fertilizer and create damage by increasing nutrients.
Organic Wastes Domestic sewage treatment plants, food processing plants, paper mill plants, and leather tanning factories release organic wastes that bacteria consume. If too much waste is released, the bacterial populations increase and use up the oxygen in the water. Fish die if too much oxygen is consumed by decomposing organic matter. Inorganic Compounds Detergents, pesticides and many synthetic industrial chemicals are released to waterways. Many of these substances are toxic to fish and harmful to humans.