Figure 7.1 



Water Resource Regions 



New England. 101-106 

 Middle Atlantic, 201-206 

 South Atlanllc-Gull. 301-309 

 Great Ukes, 401-408 

 Ohio, 501-507 

 Tennessee, 601-602 

 Upper Mississippi, 701-705 

 Lower Mississippi, 601-803 

 Sourls-Red-Rainy, 901 

 Missouri, 1001-1011 

 Artiansas-While-Red. 1101-1107 



Texa»<3ull, 1201-120S 

 Rio Grande. 1301-1305 

 Upper Colorado, 1401-1403 

 Lower Colorado, 1501-1503 

 Great Basin, 1601-1604 

 Columbia-North Pacific, 1701- 

 Callfomia-South Pacific, 1801 

 Alaska, 1901 

 Hawaii. 2001-2004 

 Caribbean, 2101-2102 



1707 

 ■ 1807 



Three categories of water use are generally recog- 

 nized: (1) Withdrawal use which removes water from 

 its natural course, uses it, and then returns it to 

 a stream or underground source where it is avail- 

 able for reuse; (2) consumptive use which represents 

 that portion of the withdrawal consumed through 

 evaporation, transportation, or by discharge to irre- 

 trievable locations: and (3) instream uses such as 

 boating, fishing, navigation, and hydroelectric power. 



The 1975 National Water Assessment prepared by 

 the Water Resources Council contains estimates of 

 withdrawals, consumptive use, and, to some extent, 

 instream uses for 1975, with projections for 1985 

 and 2000.3 



In this report, the projections for water demand 

 beyond 2000 have been made by the Forest Service 

 by extending the general trends shown in the pro- 

 jections by the Water Resources Council. The 



^U,S. Water Resources Council. The 1975 assessment of water 

 and related land resources, op. cii. 



estimates for 1980 and 1990 are interpolated from 

 the projections of the Council. 



Water Withdrawals by Major Use 



Freshwater withdrawals were approximately 339 

 billion gallons a day in 1975 (table 7.1). Irrigation 

 was the largest withdrawal use, accounting for 47 

 percent of the total (fig. 7.2). Withdrawals for steam 

 electric cooling were second in importance (26 per- 

 cent). Another 15 percent was used in manufacturing. 

 Domestic use and mineral extraction activities 

 accounted for most of the remainder. 



Demand for water withdrawals is projected to 

 decrease to about 306 billion gallons per day by 

 the year 2000. Most of the projected decrease should 

 occur before 2000 and is concentrated in manufac- 

 turing, steam electric cooling, and irrigation. These 

 declines are expected because of increased emphasis 

 on water conservation and the adoption of tech- 



274 



