The U.S. Army Corps of Engineers is studying the adequacy of the existing ground-water supplies of North Fort Hood, located in Coryell County in central Texas and an important part of the U.S. Army's Fort Hood Military Reservation. The U.S. Geological Survey was requested to compile the available ground-water data, collect additional data, and assess the effects of the long-term development of ground water in the North Fort Hood area.
Nearly all ground water in the North Fort Hood area is withdrawn from the Hensell and Hosston Members of the Travis Peak Formation. The total average annual rates of ground-water withdrawals, mostly for public supply, has steadily increased from nearly 0.5 million gallons per day during 1955 to mare than 1.5 million gallons per day during 1980.
The principal effect of the long-term development of ground water in the area has been a large decline of water levels in wells. The water level in a well near Narth Fort Hood declined from a depth of 100 feet during 1943 to nearly 480 feet during 1982. The water level in a well at Gatesville was above ground level during 1898. A nearby well had a water level of 476 feet below land surface during 1982. The long-term average of water-level declines for wells in the area ranges from 8 to more than 9 feet per year.
The historical confined (artesian) conditions of the principal aquifer have changed to water-table conditions in some areas as the artesian head 9 drops below the base of the confining layer due to pumping. The greater storage property of the unconfined system will decrease the rate of water-level declines. However, well yields will continue to decrease in relation to the general decline of hydraulic head in the aquifer.
The ground water in the area is slightly saline and concentrations of some constituents generally exceed chemical-quality limits set by the U.S. Environmental Protection Agency for public water supplies. Hie historical chemical changes in the ground water generally are insignificant and appear unrelated to the large declines of water levels in wells of the area.
