Application of the lndex of Biotic lntegrity to Evaluate Water Resource lntegrity in Freshwater Ecosystems

The biotic and abiotic: processes involved in the environmental degradation of freshwater ecosystems are often complex, and their combined effects are not easily measured. Many human activities across the landscape contribute to degradation, including discharge of domestic, agricultural, and industrial effluents; cultural eutrophication; acidification; erosion and sedimentation following human modification of watersheds; straightening, deepening, and clearing of stream channels; drainage of wetlands and impoundments of streams; flow alterations caused by dam operation and water diversions; overharvest of biota; and introduction of nonnative species. Estimating ecosystetn health and integrity may be the best way to assess the total effects of these activities on aquatic environments (Karr 1991).