Functionally defined as the condition of the aquatic community that inhabits unimpaired water bodies of a specified habitat as measured by community structure and function (USEPA Region 5).

All wetlands and deep-water habitats within a channel, with two exceptions--wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens and habitats with water that contains ocean-derived salt in excess of 0.5 part per thousand.

An action that has an apparent direct or indirect negative effect on the conservation and recovery of an ecosystem component listed as threatened or endangered [U.S. Forest Service (USFS)].

All forms of monitoring conducted beyond the immediate influence of a discharge pipe or injection well and may include sampling of sediments and living resources [U.S. Environmental Protection Agency (USEPA) Region 5].

A. Other categories of data (see Water-quality data ) critical to interpreting water-quality data and formulating courses of action. These ancillary categories of data will be considered only as they relate to information management and data sharing. Ancillary data critical to water-quality decisionmaking include, but are not limited to, land use/l [..]

An association of interacting populations of aquatic organisms in a given water body or habitat (USEPA Region 5).

The stream channel, lake or estuary bed, water, and (or) biotic communities and the habitat features that occur therein (USFS).

Environments characterized by the presence of standing or flowing water (USFS).

A body of rock that is sufficiently permeable to conduct ground water and to yield economically significant quantities of water to wells and springs [Bates, Robert L., and Jackson, Julia A., eds., 1987, Glossary of Geology (3d ed.): Alexandria, Va., American Geological Institute, p. 33].

Water bodies for which the State is able to make use-support decisions based on actual information. Such waters are not limited to those that have been directly monitored; it is appropriate in many cases to make judgments based on other information (USEPA Region 5, modified).