Water quality law

Water quality laws govern the release of pollutants into water resources, including surface water, ground water, and stored drinking water. Some water quality laws, such as drinking water regulations, may be designed solely with reference to human health. Many others, including restrictions on the alteration of the chemical, physical, radiological, and biological characteristics of water resources, may also reflect efforts to protect aquatic ecosystems more broadly. Regulatory efforts may include identifying and categorizing water pollutants, dictating acceptable pollutant concentrations in water resources, and limiting pollutant discharges from effluent sources. Regulatory areas include sewage treatment and disposal, industrial and agricultural waste water management, and control of surface runoff from construction sites and urban environments.

The Earth's hydrosphere is ubiquitous, fluid, and complex. Within the water cycle, physical water moves without regard to political boundaries between the Earth's atmosphere, surface, and subsurface, through both natural and man-made channels. Consequently, water quality laws must define the portion of this complex system subject to regulatory control. Regulatory jurisdictions may be coterminous with political boundaries (e.g., certain treaty responsibilities may apply to water pollution in all of Earth's international waters). Other laws may apply only to a subset of waters within a political boundary (e.g., a national law that applies only to navigable surface waters), or to a special class of water (e.g., drinking water resources). Cross-jurisdictional waters may be subject to cross-jurisdictional agreements. Even within jurisdictions, complexities may arise where water flows between subsurface and surface, or saturates land without permanently inundating it (wetlands).

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