To assist the Congress and the administration in deciding the future course of the national waer-quality program, we reviewed the findings of recent studies on the quality of waer in U.S. rivers and streams and the progress that has been made toward the goals of the Clean Water Act. From our in-depth review and synthesis of the literature and the advice of expert consultants, we formulated four evaluation questions: 1. What is the present condition of the nation's water quality? 2. How has the nation's water quality changed over time? 3. What pollution sources degrade water quality? 4. What has been the effect of the Construction Grants Program on water quality? In addition to reviewing and synthesizing relevant inforrmation from the studies that addressed these questions, we evaluated the methodologies they employed to reach their conclusions."--Page 12.