Ground-water development in Utah and effects on ground-water levels and chemical quality

Abstract

Systematic ground-water development began in Utah shortly after settlement by Mormon pioneers in 1847. By 1939, about 230,000 acrefeet per year of ground water was being withdrawn from wells for irrigation, public supply, industrial use, and rural-domestic and stock supply. Withdrawals increased from about 600,000 to 700,000 acre-feet per year during 1963-67 to about 800,000 to 900,000 acre-feet per year during 1989-93, with a peak of 940,000 acre-feet in 1990. Most ground-water withdrawals from wells have been from unconsolidated basin-fill deposits in 13 areas along or near the eastern edge of the Basin and Range Province, which extends from the northern edge of Utah to its southwestern part. The proportions of withdrawals for various uses have changed; in 1964, 72 percent of withdrawals was for irrigation and II percent for public supply, whereas in 1993,64 percent was for irrigation and 21 percent for public supply. Long-term withdrawals from wells have caused declines in water levels in parts of western Utah from the 1940's and 1950's to 1994; the withdrawals apparently have caused local increases in dissolved-solids concentrations in ground water. Water levels have declined as much as 67 feet owing to withdrawals for public supply and industrial use in northwestern Utah, and as much as 88 feet owing to withdrawals for irrigation in southwestern Utah. Declines of this magnitude, however, are confined to local areas of large withdrawals. Withdrawals for irrigation apparently have caused increases in dissolved-solids concentrations in ground water in at least six irrigated areas of western Utah. Minor land subsidence related to compaction of basin-fill deposits caused by water-level declines has been observed locally in southwestern Utah.