A water-quality reconnaissance in the Duchesne River basin and some adjacent drainage areas, Utah, covered an area of about 4,400 square miles (11,400 square kilometres)--about 4,000 square miles (10,360 square kilometres) in the Duchesne River basin and the remainder in the drainage areas of Pariette Draw and Pelican Lake. Data were obtained by the U.S. Geological Survey one or more times at 108 sites during the period March 1973 to September 1974 and by the Geological Surveyor other Federal agencies at 49 other sites during earlier years.