Scope: This report summarizes part of the hydrologic data needed to determine the effects of streamflow on ground-water storage. The report includes (1) streamflow data at selected points between the water-conservation reservoirs on the Salt and Verde Rivers and the Gila River as Gillespie Dam, (2) changes in ground-water levels in 169 observation wells from February 1978 to May 1980, (3) an estimate of the streamflow losses along the Salt and Gila Rivers between Granite Reef and Gillespie Dams from March 1978 to June 1980, and (4) the infiltration rates on May, 9, 1979, for the Salt River downstream from Granite Reef Dam. Most of the hydrologic data in this report are available in computer-printout form and may be consulted at U.S. Geological Survey offices in: Federal Building, 301 West Congress Street, Tucson, and Valley Center, Suite 1880, Phoenix. Copies of the data can be obtained at private expense.