Total fresh and saline withdrawals during 1990 were an estimated 408,000 million gallons per day (Mgal/d) for all offstream water-use categories (public supply, domestic, commercial, irrigation, livestock, industrial, mining, thermoelectric power), or 2 percent more than the withdrawals estimated for 1985. Average per-capita use was 1,620 gallons per day (gal/d) of freshwater and saline water and 1,340 gal/d of freshwater. Total surface-water withdrawals were an estimated 327,000 Mgal/d during 1990, or 1 percent more than during 1985. About 68,200 Mgal/d of surface water withdrawn (21 percent) was saline water. Total ground-water withdrawals were an estimated 80,600 Mgal/d, or 9 percent more than during 1985. About 99 percent of groundwater withdrawn was freshwater. The use of reclaimed wastewater averaged about 750 Mgal/d, or 30 percent more than during 1985.
A comparison by water-resources region (figure 1 (GIF file) (or as a (PostScript file (621Kb)); (table 1) 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Mid Atlantic, South Atlantic-Gulf, Pacific Northwest, California) accounted for nearly one-half of the total water withdrawn in the United States. About 54 percent of the Nation's total withdrawals were in the East (water-resources regions east of and including the Mississippi regions). These regions account for about one-third of the Nation's land area.
A similar comparison of total withdrawals by State
indicates that California accounted for the largest withdrawals, 46,800 Mgal/d, more
than the total withdrawn in Texas and Idaho, the next largest users. Some 20
States and the District of Columbia had less water withdrawn for offstream uses
during 1990 than during 1985.
Table 2--Total withdrawals by State
Figure 2a--Total withdrawals by State: Externally viewable GIF file (60 Kb), or PostScript file (509Kb)
Figure 2b--Surface-water withdrawals by State: GIF file, or PostScript file (968Kb)
Figure 2c--Ground-water withdrawals by State: GIF file, or PostScript file (968Kb)
Irrigation is the largest category of freshwater use and thermoelectric power is the largest category of freshwater and saline water use. The California and Missouri Basin water-resources regions accounted for 21 percent of total freshwater withdrawals during 1990. In these water-resources regions, 73 percent of the withdrawals were for irrigation ((table 3). The State of California accounted for the most freshwater withdrawn for public supply, domestic, and irrigation, and the most saline water withdrawn for thermoelectric power (table 4). Largest surface-water withdrawals occurred in the Mid Atlantic region which is fifteenth out of twenty-one regions in land area. Of the 45,000 Mgal/d withdrawn in the Mid Atlantic region, 56 percent was saline water used for thermoelectric power plants (table 5). The State of California led the Nation in both freshwater and saline surface-water withdrawals (table 6). Five water- resources regions, the Lower Mississippi, Missouri Basin, Arkansas-White-Red, Pacific Northwest, and California, accounted for 75 percent of the nation's irrigation ground-water withdrawals (table 7). The State of California accounted for 18 percent of total ground-water withdrawals. Irrigation was the predominant use of ground water in 22 states, most located in the West (table 8).
Freshwater consumptive use in the East was about 12 percent of the freshwater withdrawn in the East and accounted for 21 percent of Nation's freshwater consumptive use (figure 3 (GIF file), or as a PostScript file (621Kb)). By comparison, freshwater consumptive use in the West was about 44 percent of freshwater withdrawals. The higher consumptive use in the West is attributed to the fact that 90 percent of the total water withdrawn for irrigation occurred in the West and irrigation accounts for the largest part of consumptive use. California accounted for the largest consumptive use (figure 4), or as a PostScript file (508Kb)).
The distribution of per-capita freshwater withdrawals by State is shown in figure 5 (GIF file), or as a PostScript file (508Kb)) and table 2. High per-capita values are characteristic of thinly populated states having large acreages of irrigated land such as Idaho, Montana, and Wyoming. In contrast, figure 6 (GIF file), or as a PostScript file (508Kb)) shows the intensity of freshwater withdrawals by State in million gallons per day per square mile. The smaller states in the northeast show the most intense withdrawals by area.
For an overview of how the 339,000 Mgal/d of freshwater withdrawn during 1990 was used, the eight offstream categories mentioned above have been combined into five major categories: public supply, domestic and commercial, irrigation and livestock, industrial and mining, and thermoelectric power. The source (withdrawals), use (withdrawals, deliveries), and disposition of freshwater for each category of use are summarized in figure 7: (A) view as an inline graphic, or (B) view as an external GIF file, or (C) view as a PostScript file (30K). The source column shows the proportion of withdrawals by source and the distribution of withdrawals by water-use category. Source data indicate, for example, that surface water was the source of 259,000 Mgal/d of freshwater, or 76.5 percent of total freshwater withdrawals in the United States. Of the 259,000 Mgal/d of surface water, 50.2 percent was withdrawn directly for thermoelectric power. Public supply is considered a source of water and figure 7 shows the total quantity of water withdrawn by public supply, the percentage of surface and ground water withdrawn, and the percentage of water delivered to the other water-use categories. The use column shows total freshwater use for each category and the percentage each category represents of total offstream water use. In addition, the use column shows the proportion of the source (surface water, ground water, public supply) and disposition (consumptive use, return flow) for each category. The use data indicate, for example, that domestic and commercial use totaled 39,100 Mgal/d, (including losses in the public-supply distribution system), or 11.5 percent of the Nation's total freshwater withdrawals. Of this 39,100 Mgal/d, 85.2 percent was supplied by public-supply systems, and 82.7 percent was returned to a surface- or ground-water source after use. The disposition column shows the quantity of consumptive use and return flow after use. The disposition data indicate that of the total freshwater withdrawn, consumptive use was 94,000 Mgal/d, or 27.8 percent, and return flow was 245,000 Mgal/d, or 72.2 percent (including 27,500 Mgal/d of irrigation conveyance losses). Irrigation accounted for 84.3 percent of consumptive use and thermoelectric power accounted for 52.0 percent of return flow.