U.S. Geological Survey U.S. Geological Survey The U.S. Geological Survey's National Water Quality Assessment (NAWQA) Program is designed to assess the status and trends in the Nation's water quality and to develop an understanding of the major factors that affect water quality conditions and trends. Evaluating water quality at a spatial scale from local to national, the program integrates physical, chemical, and biological components. NAWQA has developed nationally consistent biological sampling methods so that results are comparable across different river basins and geographic regions. The biological components of the NAWQA program include ecological studies and studies of contaminants in biota. Ecological studies use a community level approach including algae, benthic invertebrates, and fish. This information will be integrated with hydrology, land use, instream and riparian habitat, and water and sediment chemistry to better assess water resources. The analysis of trace elements and synthetic organic compounds in biological tissues permits an assessment of the occurrence and distribution of contaminants in surface water resources. The results from this integrated, basin-level approach will enable resource managers to better understand and manage aquatic ecosystems and species of special concern.