The Ogallala-Roger Mills aquifer covers approximately 400 square miles in west-central Oklahoma and is part of the High Plains aquifer which underlies portions of 8 states in the central United States. It is primarily located in western Roger Mills County with a small area located in northwestern Beckham County. The aquifer consists of semi-consolidated sediments of the late Tertiary-age Ogallala Formation and unconformably overlies Permian-age Elk City Sandstone, Doxey Shale, and Cloud Chief Formation. It is composed of poorly to moderately cemented layers of tan to white sand, gravel, clay, and silt. The thickness of the aquifer decreases from west to east across the study area. The maximum thickness is about 335 feet but generally ranges from 0-250 feet. Recharge to the aquifer is primarily due to infiltration of precipitation. Other sources of recharge include streams, subsurface inflow, and return irrigation flow.
The Ogallala-Roger Mills aquifer provides water for primarily irrigation, livestock, industrial, municipal and domestic purposes with well yields averaging 50 gallons per minute. Public water supply systems that rely on the aquifer include the Red Star Rural Water District and the Town of Reydon. Total dissolved solids concentrations range from about 250 to 1100 mg/L. The chemical composition of the groundwater in the Ogallala ranges from calcium bicarbonate to sodium bicarbonate and is generally considered good for drinking water.