The Upper Washita watershed (HUC 11130302) covers approximately 2,934 square miles in southwestern Oklahoma. The hydrology of the watershed is primarily characterized by the Washita River, which flows through the area and is fed by numerous tributaries. The watershed is prone to flash flooding, particularly during heavy rain events. Snowpack in the area is generally minimal, with very little accumulation occurring on an annual basis. Surface water in the watershed is primarily used for agricultural purposes, and several reservoirs have been constructed to assist with irrigation efforts. The primary constituents of these reservoirs include sediment and nutrients from agricultural runoff, which can lead to water quality issues. The region experiences a semi-arid climate, with hot summers and mild winters. The area has experienced a trend of decreasing precipitation in recent years, which has led to increased water stress for agricultural and other users of surface water in the area.