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Diagnostics
Aquatic Stressors
Section 303 of the 1972 Clean Water Act requires States, Territories, and Tribes to develop lists of waters that are impaired based on biological, chemical, or physical criteria. For impaired waters, the Clean Water Act mandates that States, Territories, and Tribes impose limits on the amount of pollutants that a waterbody can receive; this limit is known as a Total Maximum Daily Load, or TMDL. In cases in which the impairment is judged to exist based on biological criteria, it is necessary to diagnose the cause(s) of impairment prior to the establishment of a TMDL. The nationwide scope of this problem is enormous: approximately 44% of stream or river miles; 49% of lakes, reservoirs, and ponds; 98% of Great Lakes shoreline waters; and 42% of estuaries have been designated as impaired based on biological criteria.
To determine the causes of biological impairment, waterbodies must be considered within the context of their watershed; consequently, EPA's research plan to study aquatic stressors includes development of methods and tools to enable this work. The Aquatic Stressors research plan lays out five projects which share the goal of supporting the TMDL process and improving the current state of the science of monitoring and assessment. Research in under this topic includes development of the following:
- a conceptual model and a framework for information management;
- a classification framework;
- diagnostics and case studies to test their application;
- generic models with which to evaluate the interactions of multiple stressors; and
- a decision-support system.
View information about the Implementation Plan for Diagnostics Research within the Aquatic Stressors PDF file. (PDF, 197 pp, 3.21 MB, About PDF).
