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Water Quality: The What, Where, and How of Degraded Water

Sources of Water Degradation

Poor water quality is a function of three problems: water pollution, loss of instream flows, and degraded physical and biological habitat conditions. Pollution sources are generally divided into point sources (pipes) and nonpoint sources (runoff). Point sources include discharges from industrial operations and municipal sewage plants. These are the most regulated sources under the Clean Water Act. Runoff that is collected in a pipe or channel system, such as urban stormwater and dairy farms, are also point sources; regulation of stormwater is relatively new. Nonpoint sources include logging, farming, mining, grazing, and urban development. These sources are not regulated under the Clean Water Act and are only controlled to the degree that an individual state chooses to do so. Controls for nonpoint sources are termed "Best Management Practices" or BMPs. These BMPs may be required by state statute or may be entirely voluntary. Preservation of sufficient instream flows for fish is also a matter purely of state law. Finally, physical and biological changes -- such as streams that have lost their natural curves, are suffering from undercut stream banks and lack of large woody debris -- cause serious harm to aquatic life and the integrity of streams. More...

Effects of Pollution

Pollution effects are dependent upon the different uses of water, the types of pollution, and the amounts. Aquatic species -- such as fish, amphibians, shellfish, and the food chain upon which these species depend B require conditions that support basic life functions. Pollution that depresses natural levels of dissolved oxygen, alters natural ranges of pH, temperature and sediment, prevent certain life cycle stages from occurring, from being successful, or from taking place in the proper time period. At acute levels, these pollution problems cause death. These aquatic species, as well as fish-eating people, birds, and mammals, are also affected by toxic contaminants and heavy metals. At sub-lethal levels, these pollutants cause longer term problems, including immune deficiency disorders, chronic diseases, cancer, brain function deficiencies, and reproductive problems. The pollutants that cause these effects have been termed "endocrine disrupters" or "environmental estrogens." They can cause effects at low doses. For example, in the Northwest, studies show that juvenile salmon staying a mere three weeks in Puget Sound's contaminated estuaries suffer measurable detrimental effects, while toxic contaminants in the Columbia River are causing reproductive failure in bald eagles and impairment of reproductive organs in mink. In addition, people are affected by human pathogens B such as salmonella, polio, hepatis B that can cause serious illnesses and death to people who are exposed to them through recreation or inadequately treated drinking water. More on Effects of Pollution..

Information About Degraded Water Bodies

Data and information are collected by many government agencies that monitor water quality, as well as private companies and private citizens. The Clean Water Act requires dischargers with permits to report certain information to state and federal pollution regulatory agencies, in exchange for the privilege of discharging pollution into public waters. The state is responsible for monitoring waterbodies and reporting general trends to EPA through the biannual 305(b) Report. Some of these data, in addition to data collected by other reputable agencies and entities, are used to produce the 303(d)(1) List, a list of waters that violate water quality standards and require clean-up plans. The Toxics Release Inventory (TRI) tracks pollution discharges or emissions of certain chemicals.


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