This report is one in a series of reports prepared by the U.S. Geological Survey, beginning in 1937, on the ground-water resources in the Houston district. The Houston district includes Harris and Galveston Counties, and parts of Brazoria, Fort Bend, Waller, Montgomery, Liberty, and Chambers Counties. The primary emphasis of this report includes ground-water resources information for the district from 1985-89. Some data collected before 1985 and in early 1990 are included to present long-term trends and relations.

Ground-water withdrawal in the Houston district decreased from 451 to 419 Mgal/d (million gallons per day) between 1985 and 1989. Public supply used 77 percent of the ground water withdrawn in the district in 1985. From 1985 through 1989, withdrawals for public supply decreased from 349 to 338 Mgal/d, withdrawals for industrial use decreased from 37 to 32 Mgal/d, and withdrawals for irrigation use decreased from 65 to 49 Mgal/d.

From 1985 through 1989, ground-water withdrawals decreased from about 197.9 Mgal/d to about 166.9 Mgal/d in the Houston area and increased from about 179.5 Mgal/d to about 180.8 Mgal/d in the Katy area, and remained constant at about 67 Mgal/d in the rest of Harris County. Galveston County ground-water withdrawal decreased from about 6.1 to 4.0 Mgal/d during 1985-89.

During 1977-90, water levels in wells completed in the Chicot aquifer in the eastern part of the Houston district rose as much as 160 ft (feet) and declined as much as 80 ft in the western part. During 1985-90, water levels in wells completed in the Chicot aquifer in the western part of the Houston district rose as much as 140 ft, and declined as much as 40 ft in the western part.

During 1977-90, water levels in wells completed in the Evangeline aquifer in the southeastern part of the Houston district rose as much as 140 ft and declined as much as 200 ft in the northwestern part. During 1985-90, water levels in wells completed in the Evangeline aquifer in the eastern part of the Houston district rose as much as 40 ft, and declined as much as 140 ft in the northern part.

Dissolved-chloride concentrations in water from wells in the Houston district have not changed more than 100 mg/L during 1985-89, except for a decrease at one well in the eastern part of Galveston County. Well KH-65-48-316 yielded water with dissolved-chloride concentration decreasing from 720 mg/L in 1986 to 590 mg/L in 1989.