An analysis of water quality data from twenty-one water quality surveillance stations located in the South Platte River Basin of Colorado was conducted. The data collected from 1968 through 1972 indicate significant deterioration of surface water quality in the Denver Metropolitan Area. Total and Fecal Coliform concentrations have increased by two to three orders of magnitude in recent years along with increased BOD5 concentrations, and Dissolved Oxygen concentrations have sometimes dropped below acceptable limits (less than 5 mg/l). The analysis indicates a need to improve water quality with respect to these parameters in order to achieve proposed water quality objectives. A monitoring system is proposed to improve data reliability and provide information on previously undefined variables.