The estimated withdrawal use of water in the United States during 1955 was about 740,000 mgd (million gallons per day). Withdrawal use of water requires that it be removed from the ground or diverted from a stream or lake. In this report it is divided into five types: public supplies, rural, irrigation, self-supplied industrial, and waterpower. Consumptive use of water is the quantity discharged to the atmosphere or incorporated in the products of the process in which it was used. Only a small part of the water withdrawn for industry was consumed, but as much as 60 percent of the water withdrawn for irrigation may have been consumed.
Of the water withdrawn in 1955 about 1,500,000 mgd was for generation of waterpower, and all other withdrawal uses amounted to only about 240,000 mgd. Surface-water sources supplied 194,000 mgd and groundwater sources supplied 46,000 mgd. The amount of water withdrawn in each State and in each of 19 geographic regions is given.
The quantity of water used without being withdrawn for such purposes as navigation, recreation, and conservation of fish and wildlife was not determined. The water surface area of the reservoirs and lakes used to store water for these purposes is sufficiently large that the evaporation from this source is greater than the quantity of water withdrawn for rural and public supplies.
The amount of water used for generation of waterpower has increased 36 percent since 1950. The largest increase, 43 percent, was in self-supplied industrial water. Rural use, excluding irrigation, decreased 31 percent.
The upper limit of our water supply is the average annual runoff, nearly 1,200, 000 mgd. The supply is depleted by the quantity of water consumed rather than by the quantity withdrawn. In 1955 about one-fourth of the water withdrawn was consumed. The amount thus consumed is about one-twentieth of the supply.