The geology and ground water in a section of southern High Plains between Lubbock and Silverton, Texas

The Ogallala formation of the Pliocene series (Tertiary Age) is the chief water-bearing formation of the Southern High Plains in Texas. The Ogallala i s characterized by non-marine, brownish-gray lenticular bodies of sand and gravel, with inter-fingered beds of red, yellow, and white clay and silt. There are positive indications that the Southern High Plains are geologically and hydrologically isolated so that all of the water in the Ogallala must come from the precipitation that falls on these plains. The average annual rainfall on the Southern High Plains is about 20 inches with about 70 per cent falling during the growing season, April to September; not over 3 percent of this 20 inches ever finds its way to the water table. There are at least four separate ways to determine the amount of recharge that takes place on the Southern High Plains. First, compute the amount of natural discharge; second, estimate the recharge by water level fluctuations; third, compute recharge from data on underground flow; and fourth, use C.V. Theis method. The volume of water pumped out of the whole Southern High Plains during 1949 was approximately 1.5 million acre—feet and the total volume of ground water in storage in 1949 was about 123 million acre feet. Therefore if the present rate of withdrawal is not exceeded, the estimated life of the ground water supply would be about 80 years, providing all of the water could be removed from storage.