The Ogallala aquifer, which consists of semiconsolidated clay, sand, and gravel, is the principal source of ground water in the Oklahoma Panhandle. This aquifer commonly yields 500 to 1,000 gallons per minute (32 to 63 litres per second) and may yield as much as 2,500 gallons per minute (158 litres per second). Based on an estimated average storage coefficient of 0.1, the quantity of water stored in the Ogallala aquifer was computed at approximately 50 million acre-feet (6.17 x 101° cubic metres). Local overdevelopment of this water resource has resulted in water-level declines of more than 40 feet (12 metres) from 1966 to 1972 in some areas of concentrated well development. The amount of ground water in storage has been reduced about 2 percent during this period.
Aquifer tests indicate that transmissivity ranges from 500 to 11,800 feet squared per day (46 to 1,100 metres squared per day), the storage coefficient ranges from 0.002 to 0.11, and hydraulic conductivity ranges from 2.1 to 55 feet per day (0.6 to 16.8 metres per day). In addition to these tests, 802 specific-capacity tests were used to extend transmissivity data.
Recharge to the Ogallala aquifer is primarily from precipitation and may be as much as 1 inch (25 millimetres) per year in areas where catchment and percolation are most favorable. Discharge is primarily from pumping and a small amount of natural discharge.
Aquifers of limited importance are the Dakota Sandstone and the Cheyenne Sandstone Member of the Purgatoire Formation which provide water to irrigation wells in the southwestern part of Cimarron County. Irrigation wells generally are completed jointly in these aquifers and yields of 300 to 500 gallons per minute (19 to 32 litres per second) are common. Water levels in these aquifers have not shown the pronounced declines that have occurred in the Ogallala aquifer. Permian red beds provide only small quantities of water to domestic and stock wells.
Water in the Ogallala aquifer, Dakota Sandstone, and Cheyenne Sandstone Member generally has a dissolved-solids concentration of less than 500 milligrams per litre. The dissolved-solids concentration in water from the Permian red beds generally exceeds 500 milligrams per litre and locally exceeds 2,000 milligrams per litre.
