Pumpage of ground water and changes in water levels in Galveston County, Tex., 1952-57.
No important changes in the total rate of withdrawal from wells in Galveston County took place from 1952 to 1957. The average rate was about 25 mgd (million gallons per day). However, the amount of water pumped for public supply increased from about 13.3 mgd in 1951 to about 15.3 mgd in 1957 and the amount of water pumped for irrigation increased from about 500,000 gpd in 1951 to an estimated 2 mgd in 1957. During the same period the amount of water pumped for industrial supply decreased from 12.8 mgd to about 6 mgd. Use in Galveston County of surface water from the Brazos River also remained about the same from 1952 to 1957--about 70,000 acre-feet per year. Industrial use of surface water increased from 18.700 acre-feet in 1951 to 43,200 acre-feet in 1957. Irrigational use of surface water for growing rice declined from about 50,000 acre-feet in 1951 to about 22,500 acre-feet in 1957. Water levels in wells in Galveston County changed very little or declined slowly in the period 1952-57. Water levels in wells in the vicinity of the city of Galveston's well field near Alta Loma have declined very slowly since 1945, but have shown more seasonal fluctuation since 1954 because of seasonal pumping-rate changes. Water levels in the Texas City area changed very little between 1952 and 1957, but the water levels in wells in the shallower sands of the Beaumont clay in northern Galveston County continued to decline at an average rate of 2.5 to 3.5 feet per year from 1952 to 1957. The land surface continued to subside in the period 1952-57, although in the Texas City area, where most of the subsidence has taken place, the rate of subsidence lessened. The chemical quality of the water from wells was about the same in the period 1952-57 as in 1951, except in a few wells in the Alta Loma and Texas City areas. Most of the wells in the city of Galvestons old well field near Alta Loma yielded water of about the same chloride content in 1952-57 as in 1951, except the water from well 2, which increased in chloride content at about the same rate as from 1946 to 1951. However, the chloride content of water from well 2 was less in 1957 than that from wells 3,4, and 8, which was between 750 and 900 parts per million from 1952 to 1957. The chloride content of water from wells in the city of Galveston's new well field near Alta Loma changed very little from 1952 to 1957, although the chloride content of water from well 10 increased to about the same as that in well 9 in 1957. In the Texas City area a few of the wells in the upper sands of the Beaumont clay yielded water that had a higher chloride content than in 1951, but the increase was small and may or may not be indicative of future changes.