During 1975-79, total withdrawals of ground water in the Houston district decreased by 9.7 percent. This percentage represents a decrease from 505 million gallons per day (22.1 cubic meters per second) during 1975, to 456 million gallons per day (20.0 cubic meters per second) during 1979. The decrease resulted from an increased use of surface water that became available from Lake Livingston on the Trinity River during late 1976. During 1975-79, withdrawals of ground water decreased in the Pasadena, Katy, Baytown-La Porte, Johnson Space Center, Texas City, and Alta Loma areas but increased in the Houston area. The decreased withdrawals in the Katy area resulted partly from a small decrease in the acreage of rice planted, but mostly from a decrease in water needed for irrigation during 1979. The pumping of ground water increased in the Houston area because of the growth in population.
From spring 1975 to spring 1980, water levels rose in the southeastern one-half of the district and declined in the northwestern one-half. The maximum rise of water levels in wells in the Chicot aquifer was 110 feet (33.5 meters); the maximum rise in wells in the Evangeline aquifer was 150 feet (45.7 meters). The maximum decline of water levels in wells in the Chicot aquifer was 60 feet (18.3 meters); the maximum decline in wells in the Evangeline aquifer was 70 feet (21.3 meters).
No significant changes occurred in the chloride concentration in water from wells in the Alta Loma area during 1975-79. The concentration of chloride in water from a well completed in the middle part of the Chicot aquifer at Hitchcock is increasing, probably because of updip migration of the freshwater-saltwater interface.
