Colxmbla River Basin 



The principal river basin in the 

 Pacific Hortbwest is the Columbia River 

 Basin. This river system llkevlse has the 

 greatest multipurpose water uses existing 

 and proposed. It has supported very leorge 

 runs of anadromous fishes for whose con- 

 tinuation, hioge sums of money have been 

 spent. This water q\iallty study has con- 

 fined itself within the Columbia River 

 Basin. Figure 1 shows the drainage bound- 

 aries of the Basin. There are seme 259,000 

 square miles in the drainage basin, of 

 ^ich 39,700 are In Canada. It includes 

 the majority of land area in the States of 

 Washington, Idaho and Oregon, the western 

 part of Montana, and smaller areas in 

 Nevada, Wyoming and Utah, cooprlsing about 

 seven percent of the nation's area. 



The Colimbla River has its headwaters 

 in Coliaibia Lake, British Columbia, about 

 70 miles north of the International border 

 at an elevation of 2,650 feet. After flow- 

 ing U65 miles through Canada in a circui- 

 tious manner, the river enters the United 

 States near the northeast comer of Wash- 

 ington. It flows through Washington in a 

 series of big bends and beccxies the border 

 between Washington and Oregon as it flows 

 westward to the Pacific Ocean. Between 

 headwaters and the ocean, the river is some 

 1,200 miles long. Its ann\iftl average dis- 

 charge is around 160,000,000 acre -feet of 

 water (or 220,000 cubic feet per second) 

 that flows into the Pacific Ocean. The 

 headwaters of the Columbia and its princi- 

 pal tributaries are in the mountains where 

 precipitation is fairly high. Mo\mtaln 

 snow packs produce ground storage pliis 

 seasonal peak flows in late spring. 



The central part of the Columbia, like 

 its principal tributary, the Snake, lies in 

 an arid region where Irrigation is necessary 

 for diversified faming. About l^, 500,000 

 acres are now (1956) under iirigation, two- 

 thirds of which are in Southern Idaho. 

 Ultimate develop»ent calls for a total of 

 about 7,500,000 acres to be irrigated (3)- 

 (See table 1 and figs. 3 and U.) 



Because of its rapid fall from head- 

 waters to the ocean, the Columbia and its 

 tributaries offer many sites for hydroelec- 

 tric -pcrwer developnent. Despite the fact 

 that there are now nearly 200 hydroelectric - 

 power developoents in the Basin, only about 



Tkbl* 1. — IrrlCfttloa, cxlstiac «ad propoa«4,' 

 tributary aboT* statad location 



u 



1/ Includ«B 80,000 acras In Caxuul« -- 00 eatimata oa 

 proposad futura irrl^atloa in Canada. 



2/ rroB rafaranoaa (3), (^)> and (6). 



y EatlaaM fna rafaranca (3). 



IRRIGATION, EXISTING AND PROPOSED 

 FIG. 3 



