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Glossary of Environmental Terms

Term Definition

Refers to section 303 subsection “d” of the Clean Water Act, which requires states to develop a list of water bodies that do not meet water quality standards (a “§303(d) list”). This section also requires TMDLs be prepared for listed waters. Both the list and the TMDLs are subject to EPA approval.


Refers to section 305 subsection “b” of the Clean Water Act, which requires that each state prepare a report every two years that describes the quality of that state’s surface water (referred to as a “§305(b) report”) and submit that report to EPA. Also see Integrated Report.

§319 Subgrants

Refers to grants authorized under section 319 of the Clean Water Act. This section established a grant program under which states, territories, and tribes may receive funds to support a wide variety of nonpoint source pollution management activities, such as technical assistance, training, and demonstration projects. The grant money is supplied by EPA to DEQ; DEQ oversees “subgrants” for specific projects.

§401 Certification

Clean Water Act Section 401 certification allows each state to have input into projects that may affect its waters. It is required for any permit or license issued by a federal agency for any activity that may result in a discharge into waters of the state to ensure that the proposed project will not violate state water quality standards. DEQ is responsible for issuing §401 certifications in Idaho.

Abate (Abatement)

To reduce the degree or intensity of, or eliminate, pollution.

Acquatic Assemblage

See Assemblage.


A volume of water that would cover one acre to a depth of one foot. Often used to quantify reservoir storage and the annual discharge of large rivers.

Acutely Hazardous Waste

A listed hazardous waste that is so dangerous that it can be fatal to humans in small doses (e.g., certain pesticides).


Fish whose life history involves seasonal migration from lakes to streams for spawning.

Administrative Record

All documents that are considered or relied on in making technical or policy decisions.


The attachment of one substance to the surface of another. Clays, for example, can adsorb phosphorus, meaning that phosphorus can attach itself to clay.


A process by which water becomes charged with air directly from the atmosphere. Dissolved gases, such as oxygen, are then available for reactions in water.


Describes life, processes, or conditions that require the presence of oxygen.

Agricultural Burning

A method of removing crop residue to control disease, weeds, and pests; to reduce the need for herbicides and pesticides; and to reduce fire hazards. It is also a method of clearing irrigation ditches and canals.

Air Pollutant

Any substance in air that could, in high enough concentration, harm humans, other animals, vegetation, or material. Also see pollutant.

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