The primary goal of the Clean Water Act is “to restore and maintain the chemical, physical and biological integrity of the nation's waterways.” One measure of that integrity is the dissolved oxygen content of water, which can be dangerously altered by the structure of dams and hydroelectric plants. However, two federal courts of appeals have held that Congress did not intend to regulate the destructive discharges of dams under the Clean Water Act. This paper briefly describes the relationship between dissolved oxygen and water quality and explains how dams and hydroelectric facilities pollute the surrounding waters. The paper concludes that the erroneous decisions of the two circuit courts are serious threats to the economic viability and biological integrity of the nation's waterways. Actions by both Congress and the Environmental Protection Agency are suggested.