The National Research Councils' (NRC) "Committee on the Assessment of Water Reuse as an Approach to Meeting Future Water Supply Needs" pointed out the need for the development of ecological assessments describing how site-specific environmental stressors may affect aquatic life and water quality at different locations. The upper Trinity River in the Dallas-Fort Worth area, dominated by wastewater treatment plant (WWTP) effluent, is heavily relied upon for municipal drinking water. Increasing water supply needs are a major issue in this rapidly urbanized, effluent-dominated watershed. This watershed is the ideal situation to develop the NRCs' mandate. Benthic macroinvertebrates, dominated in our study area by small worms and juvenile aquatic insects, live in direct association with sediment, contaminants, and colonizing microbiota (biofilms). They are an integral part of the trophic transfer of energy through the aquatic food web. Historical studies conclude that many reaches support a diverse benthic communit