Low-flow characteristics of streams in the Deschutes River basin, Washington

The purpose of the study was to determine the magnitude and frequency of low flows of streams in the Deschutes River basin.The streams in the basin usually have their low flows in August and September.Seven-day low flows were smallest in 1952 when annual rainfall at the Olympia airport was also the least during the 1945-75 period of continuous gaging-station records in the basin.The magnitude and frequency of seven-day low flows were estimated for 23 streamflow sites, either from frequency analysis of data at long-term stations or from correlation of measured or computed discharges at a stream flow site with data at a long-term station.Seven-day low flows ranged from no-flow at one tributary of Deschutes River having a drainage area of 1.85 square miles to 98 cubic feet per second for Deschutes River near its mouth, where the drainage was 162 square miles.Mean monthly flows were determined for two long-term stations and estimated for the months of July to September for the other streamflow sites.Miscellaneous streamflow measurements made over the years by the U.S. Geological Survey are listed in the Appendix.1.