EPA to develop and publish water quality criteria and information on methods for measuring water quality, including biological monitoring and assessment methods to determine (1) the effects of pollutants on aquatic community components (e.g., plants, plankton, fish) and community attributes (e.g., diversity, productivity, stability) in any body of water, and (2) the factors necessary to restore and maintain the ecological integrity of all navigable waters (EPA, 1990).
Development and use of biological criteria also will help states to meet the intent of several other legislative acts that require an assessment of risk to the environment (including resident aquatic communities) to determine the need for regulatory action (EPA, 1990). Some examples of the latter are the Comprehensive Environmental Response, Compensation, and Liability Act of 1980; the Federal Land Policy and Management Act of 1976; the Fish and Wildlife Conservation Act of 1980; NEPA; the Resource Conservation and Recovery Act first enacted in 1976; and the Wild and Scenic Rivers Act passed in 1968.
Under the Clean Water Act, states were required to begin instituting narrative biological criteria into state water quality standards during 1991-1993; numeric criteria and full implementation are scheduled to occur within a few years (EPA, 1990). These requirements also apply to federal agencies responsible for the management of large tracts of public land (e.g., the U.S. Forest Service and Bureau of Land Management), especially in the western United States. Narrative biological criteria are general definable statements of conditions or attainable goals of biological integrity and water quality for a given use designation; numeric criteria establish specific values based on measures such as species richness, presence or absence of indicator taxa (taxonomically related groups), and trophic composition.
A good example of cooperation among federal agencies in addressing these aspects using biological assessment is the cooperative survey of the Apalachicola-Chattachoochee-Flint River Basin recently initiated by NAWQA and the NBS (NAWQA Information Sheet, April 6, 1994). This river basin, one of the largest in the eastern Gulf Coast Plain, was known for its rich diversity of at least 45 species of unionid mussels, but these populations have either declined or died out. Mussels are sensitive indicators because they are sessile and are dependent on good water quality, physical habitat conditions, and populations of host fish. The life cycle of unionid mussels is closely linked to fish because mussel larvae are obligate parasites on fish before becoming free-living adults. Conservation efforts to protect or restore declining mussel populations require information on both mussel and fish populations in watersheds with differing