By Wayne B. Solley, Robert R. Pierce, and Howard A. Perlman
Water withdrawals in the United States during 1990 were estimated to average 408,000 million gallons per day (Mgal/d) of freshwater and saline water for offstream uses--- 2 percent more than the 1985 estimate. Total freshwater withdrawals were an estimated 339,000 Mgal/d during 1990, about the same as during 1985. Average per-capita use for all offstream uses was 1,620 gallons per day (gal/d) of freshwater and saline water combined and 1,340 gal/d of freshwater.
Offstream water-use categories are classified in this report as public supply, domestic, commercial, irrigation, livestock, industrial, mining, and thermoelectric power. During 1990, public-supply withdrawals were an estimated 38,500 Mgal/d, and self-supplied withdrawals were estimated as follows: domestic, 3,390 Mgal/d; commercial, 2,390 Mgal/d; irrigation, 137,000 Mgal/d; livestock, 4,500 Mgal/d; industrial, 22,600 Mgal/d, of which 3,270 Mgal/d was saline water; mining, 4,960 Mgal/d, of which 1,650 Mgal/d was saline; and thermoelectric power, 195,000 Mgal/d, of which 64,500 Mgal/d was saline.
Water use for hydroelectric power generation, the only instream use compiled in this report, was estimated to be 3,290,000 Mgal/d during 1990, or 8 percent more than during 1985 and about the same as estimated for 1975 and 1980.
Estimates of withdrawals by source indicate that during 1990, total surface-water withdrawals were 327,000 Mgal/d, or 1 percent more than during 1985, and total ground-water withdrawals were 80,600 Mgal/d, or 9 percent more than during 1985. Total saline-water withdrawals during 1990 were 69,400 Mgal/d, or 15 percent more than during 1985, most of which was saline surface water. Reclaimed wastewater averaged about 750 Mgal/d during 1990, or 30 percent more than during 1985.
Total freshwater consumptive use was an estimated 94,000 Mgal/d during 1990, or 2 percent more than during 1985. Consumptive use by irrigation accounted for the largest part of total consumptive use, and was an estimated 76,200 Mgal/d. Freshwater consumptive use in the East (water-resources regions east of and including the Mississippi regions) was about 12 percent of freshwater withdrawn in the East and accounted for only 21 percent of the Nation's total consumptive use. By comparison, freshwater consumptive use in the West was about 44 percent of the freshwater withdrawn in the West.
The 1990 estimates of total freshwater withdrawals and consumptive use were just slightly more than the 1985 estimates but substantially less than the 1980 estimates; this is consistent with the general trend indicated by a slackening in the rate of increase of total withdrawals from 1970 to 1975 and again from 1975 to 1980, and a decrease in total withdrawals from 1980 to 1985. Public-supply withdrawals during 1990 were 5 percent more than during 1985, and self-supplied withdrawals during 1990 compared to 1985 were as follows: domestic, 2 percent more; commercial, 95 percent more; irrigation, 0.3 percent less; livestock, 0.8 percent more; industrial, 13 percent less; mining, 44 percent more; and thermoelectric power, 4 percent more.
A comparison of total withdrawals (fresh, saline) by State indicates that 20 States and the District of Columbia had less water withdrawn for offstream uses during 1990 than during 1985. California accounted for the most water withdrawn for offstream use, 46,800 Mgal/d, more than the total of water withdrawn in both Texas or Idaho, the next largest users. A similar comparison by water-resources regions indicates that the coastal regions (New England, Mid Atlantic, South Atlantic-Gulf, Pacific Northwest, California) accounted for nearly one-half of the total water withdrawn in the United States. Total withdrawals in the East accounted for 54 percent of the Nation's total withdrawals, the same as during 1985.