Elk City Sandstone
The Elk City Aquifer is located in the southwest region of Oklahoma, primarily within Washita and Beckman counties with parts of the aquifer in Custer and Roger Mills counties. The total area of the Elk City Aquifer is approximately 246 square miles. Elk City, Sayre and smaller municipalities such as Dill city, Burns Flat, and Canute are supplied by the aquifer. Municipalities and irrigation are the main use of the aquifer. In the southwest region the climate is semi-arid with an average temperature of 58.8°F and an average annual precipitation of approximately 24.5 inches per year. The natural discharge of this aquifer is through evapotranspiration, springs, and streams. The aquifer is recharged predominantly by precipitation with some recharge by subsurface inflow and return irrigation flow. The Elk City Aquifer consists of the Elk City Sandstone, which is fine grained and a reddish color. It is the uppermost Permian-age unit in the Anadarko Basin and has a maximum thickness of 220-260 feet. Underlying the Elk City Sandstone is the Doxey Shale. The Doxey Shale is approximately 160-195 feet thick and is exposed near the edges of the aquifer, creating a natural boundary preventing the downward flow of water. As a result, seeps and springs occur at the edges of the aquifer. Above the Elk City Sandstone are sediment deposits of Late Tertiary on the western side and Quaternary on the eastern side.
The Oklahoma Water Resource Board will be conducting a 20-year update study of the aquifer that is scheduled to be completed by the end of 2014. The goals of the study include: 1) updating aquifer maps such as saturated thickness, aquifer thickness, and potentiometric surface, 2) compile groundwater use from the aquifer and, 3) incorporate Oklahoma Comprehensive Water Plan projections for management purposes.