Summary of ground-water conditions in Arizona, 1987-90

Abstract

Annual ground-water withdrawals in Arizona were 2.9, 3.3, 3.6, and 3.4 million acre-feet for calendar years 1987. 1988, 1989, and 1990. The average annual ground-water withdrawal for Arizona from 1980-89 was 3.7 million acre-feet, which was the lowest average annual withdrawal for any decade since the 1940' s. Since 1947, annual ground-water withdrawals in Arizona were at the lowest rate in 1983 and at the second lowest rate in 1987. For 1987-90, the distribution of ground-water use was 11.8 percent for municipal, 8.3 percent for industnal, 72.6 percent for agriculture, and 7.3 percent for draining irrigated lands. More than 94 percent of the ground-water withdrawals in Arizona occurred in the Basin and Range lowlands province during 1987-90. This province contains the two areas with the largest rates of ground-water withdrawal in Arizona--the Salt River Valley and the lower Santa Cruz basin. The average annual ground-water withdrawal for the Salt River Valley from 1980-89 is 1,013,000 acre-feet, which is the lowest average annual withdrawal for any decade since the 1930 's. Ground-water withdrawals in the lower Santa Cruz basin during 1990 were the lowest on record since 1940. In 1985, the Central Arizona Project began delivering Colorado River water to central Arizona to mitigate ground-water overdraft. The Harquahala basin began receiving water from the Central Arizona Project in 1985. From 1985 to 1990, ground-water withdrawals decreased from 59,000 acre-feet to 2,000 acre-feet, and water levels rose as much as 70 feet.