Sediments

Particles of soils, sand, silt, clay, and minerals wash from land and pavedareas into creeks and tributaries. In large unnatural quantities, thesenatural materials can be considered a pollutant. Construction projectsoften contribute large amounts of sediment. Certain lumbering practicesaffect sediments in runoffs. Sediments may fill stream channels and harborsthat later require dredging. Sediments suffocate fish and shellfishpopulations by covering fish nests and clogging the gills of bottom fishand shellfish.

Petroleum Products

Oil and other petroleum products like gasoline and kerosene can find theirway into water from ships, oil drilling rigs, oil refineries, automobileservice stations, and streets. Oil spills kill aquatic life (fish, birds,shellfish, and vegetation). Birds are unable to fly when oil loads thefeathers. Shellfish and small fish are poisoned. If it is washed on thebeach, the oil requires much labor to clean up. Fuel oil, gasoline, andkerosene may leak into ground water through damaged underground storagetanks.

Animal Waste

Human wastes that are not properly treated at a waste treatment plant andthen released to water may contain harmful bacteria and viruses. Typhoidfever, polio, cholera, dysentery (diarrhea), hepatitis, flu and common coldgerms are examples of diseases caused by bacteria and viruses incontaminated water. The main source of this problem is sewage getting intothe water. People can come into contact with these microorganisms bydrinking the polluted water or through swimming, fishing, or eatingshellfish in polluted waters. Often unexpected flooding of barnyards orstock pens can suddenly increase the toxic effects of animal waste inwater. Animal waste can also act as a fertilizer and create damage byincreasing nutrients. (see fertilizers)

Organic Waste

Domestic sewage treatment plants, food processing plants, paper millplants, and leather tanning factories release organic waste that bacteriaconsume. If too much waste is released, the bacteria population increasesand uses up the oxygen in the water. Fish die if too much oxygen isconsumed by decomposing organic matter.

Inorganic Compounds

Detergents, pesticides, and many synthetic industrial chemicals arereleased to waterways. Many of these substances are toxic to fish andharmful to humans. They cause taste and odor problems and often can not betreated effectively. Some are very poisonous at low concentration.

Inorganic Chemicals

Inorganic chemical and mineral substances, solid matter, and metal saltscommonly dissolve into water. They often come from mining and manufacturingindustries, oil field operations, agriculture, and natural sources. Thesechemicals interfere with natural stream purification; they destroy fish andother aquatic life. They also corrode expensive water treatment equipment,and increase the cost of boat maintenance.

Fertilizers

The major source of pollution from agriculture comes from surplusfertilizers in the runoff. Fertilizers contain nitrogen and phosphorousthat can cause large amounts of algae to grow. The large algae blooms coverthe water surface. The algae die after they have used all of the nutrients.Once dead they sink to the bottom where bacteria feed on them. The bacteriapopulations increase and use up most of the oxygen in the water. Once thefree oxygen is gone, many aquatic animals die. This process is calledeutrophication.

Heated or Cooled Water

Heat reduces the ability of water to dissolve oxygen. Electric power plantsuse large quantities of water in their steam turbines. The heated water isoften returned to streams, lagoons, or reservoirs. With less oxygen in thewater, fish and other aquatic life can be harmed. Water temperatures thatare much lower than normal can also cause habitat damage. Deep dams oftenlet extra water flow downstream. When the water comes from the bottom ofthe dam, it is much cooler than normal.

Acid Precipitation

Aquatic animals and plants are adjusted to a rather very narrow range of pHlevels. pH is a measure of the acidity of a solution. When water becomestoo acid, due to inorganic chemical pollution or from acid rain, fish andother organisms die.

Pesticides, Herbicides, Fungicides

Agricultural chemicals designed to kill or limit the growth of life formsare a common form of pollution. This pollution results from attempts tolimit the negative effects of undesirable species on agricultural cropproduction. Irrigation, groundwater flow, and natural runoff brings thesetoxic substances to rivers, streams, lakes, and oceans.