Analysis of streamflow data shows that water supply in the Washita River basin is variable, ranging from substantial amounts and almost continuous flow in the Washita River in the lower end of the basin to somewhat limited and intermittent flow in the upper part of the basin. The total yield of the basin averages 1,557,000 acre-ft per year, of which somewhat less than 1.3 percent is contributed by headwater areas in Texas. The surface waters are generally of acceptable quality for drinking purposes, excellent for irrigation uses, and suitable for many industrial purposes. In Oklahoma the high amounts of runoff tend to occur in the spring months. High runoff may occur during any month in the year but, in general, the available streamflow is relatively small in the summer. Most tributary streams have little sustained base flow and many are dry at times each year. Because of the high variability in flow, development of storage will be necessary to attain maximum utilization of the available water supplies. This report gives the average discharge at most gaging stations and at several additional sites for the 16-year period October 1938 to September 1954, used as a standard period in this report. Data are also shown on water available at several gaging stations and other sites for a given percentage of the time during the 16-year standard period. For several gaging stations data are given on minimum discharges for periods of various length during the most critical periods of record. For all gaging stations a summary of available basic data on streamflow is presented on a monthly annual basis. For other sites at which discharge measurements have been made, a tabulation of observed discharge is given. (available as photostat copy only)