Water quality criteria, 1972-2017
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Water quality criteria are the metrics used to determine water quality based on the water's designated use, such as drinking, farming, fishing, recreation, fishing, habitat for aquatic life, and industrial processes. Water quality criteria generally include the identifiable or anticipated effects of certain pollutants or contaminants in a particular water source. These criteria are used to maintain water quality in lakes, rivers, streams, and other surface bodies of water. Under the Clean Water Act, the U.S. Environmental Protection Agency (EPA) is required to set water quality criteria representing specific levels of chemicals or conditions in a body of water that are not anticipated to cause adverse effects to human and ecological health. EPA-set water quality criteria act as recommendations to states authorized to establish water quality standards within their borders.[1][2][3]
Background
Clean Water Act
- See also: Clean Water Act
Under the Clean Water Act, the U.S. Environmental Protection Agency (EPA) publishes and periodically revises water quality criteria. These criteria are based on scientific data regarding the known or anticipated effects of certain pollutants on human and ecological health, aquatic life, and recreation. The criteria also take into account pollutant levels at or below which will ensure that a body of water's quality is adequate for its designated use. Under the Clean Water Act, authorized state governments enforce water quality standards to maintain overall water quality within their borders. States can adopt EPA-set water quality criteria to determine their standards, adopt EPA criteria but modified based on site-specific conditions within their states, or develop criteria based on their own scientifically based methods.[2][4][5][6][7]
Examples of the metrics used to set surface level water quality are described below:[8][9][10]
- Human health criteria are used to determine the pollutant levels at which water would not negatively affect human health.
- Aquatic life criteria are used to determine the pollutant levels at which aquatic plants and animals can survive in surface waters. These criteria are adopted for both saltwater and freshwater aquatic life. Scientists that set these criteria examine the toxicity of certain bodies of water, how certain toxin levels affect the growth, reproduction, and overall health of aquatic organisms, and whether certain toxin levels in aquatic life could also adversely affect human health.
- Sediment quality criteria are used to determine acceptable pollutant levels in sediments inhabited by worms, plants, and micro-organisms. These organisms are consumed by fish, birds, and mammals. Scientists examine how toxins can move up the food chain and accumulate in animal tissue. In addition, scientists study toxin levels to determine which levels are safe for living organisms.
Safe Drinking Water Act
- See also: Safe Drinking Water Act
The Safe Drinking Water Act of 1974 requires the EPA to issue national drinking water standards to limit any contaminants that may pose health risks or are likely to be found in public water supplies. Federal standards apply to all privately and publicly owned water systems that regularly service at least 25 people. The EPA selects and regulates contaminants based on the following criteria:[11][12][13]
- Potential adverse health effects
- A high likelihood that a contaminant will be found in public water systems at a level and frequency that could affect public health
- Probability that regulating a contaminant will reduce health risks for people who regularly use public water systems
Contaminants regulated through national drinking water standards include microorganisms (such as harmful bacteria), radionuclides (such as cancer-causing chemicals), organic chemicals (such as benzene and pesticides), and inorganic chemicals (such as arsenic and lead). The EPA sets maximum contaminant levels at which no known or anticipated adverse health effects occur in individuals.[11][13]
In addition, the act gave state governments primary enforcement and oversight authority over public water systems (if the EPA determines a state has met the act's requirements). As of March 2017, national drinking water regulations applied to approximately 152,700 privately and publicly owned drinking water systems. Of that total, 51,350 water systems—approximately 34 percent of regulated systems—served the same residences year-round.[11]
See also
Footnotes
- ↑ U.S. Environmental Protection Agency, "Water Glossary, W," accessed November 26, 2014
- ↑ 2.0 2.1 U.S. Environmental Protection Agency, "Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000)," accessed September 7, 2017
- ↑ Business Dictionary, "Water quality criteria," accessed September 3, 2017
- ↑ U.S. Environmental Protection Agency, "Human Health Ambient Water Quality Criteria: 2015 Update," June 2015
- ↑ U.S. Government Publishing Office, "§ 1313a. Revised water quality standards," accessed September 2, 2017
- ↑ U.S. Environmental Protection Agency, "Basic Information on Water Quality Criteria," accessed September 22, 2014
- ↑ U.S. Environmental Protection Agency, "Rules and Regulations Implemented under the Clean Water Act (Water Quality Standards)," accessed September 23, 2014
- ↑ U.S. Environmental Protection Agency, "Water Quality Criteria," accessed March 9, 2015
- ↑ U.S. Congressional Research Service, "Clean Water Act: A Summary of the Law," December 15, 2010
- ↑ U.S. Environmental Protection Agency, "Water Quality Standards Regulations and Federally Promulgated Standards," accessed September 23, 2014
- ↑ 11.0 11.1 11.2 Congressional Research Service, "Safe Drinking Water Act (SDWA): A Summary of the Act and Its Major Requirements," March 1, 2017
- ↑ U.S. Environmental Protection Agency, "Summary of the Safe Drinking Water Act," accessed July 10, 2017
- ↑ 13.0 13.1 U.S. Environmental Protection Agency, "Drinking Water Regulations and Contaminants," accessed July 11, 2017
