the Columbia River Basin that will provide 

 a total of 125,000,000 acre-feet of stor- 

 age —' on the river and its tributaries. 

 This storage would make posrible almost a 

 complete regulation of the river system. 

 To accomplish this, the Corps proposes the 

 construction of 27 dams with an additional 

 131 dams, large and small, in the ultimate 

 development . 



Approximately 600,000 acres of land 

 are now irrigated above Priest Rapids (5) 

 in the Columbia River Basin and the future 

 irrigated area may exceed 2,000,000 acres. 

 Irrigation return flows from the Columbia 

 Basin Projects' future annual diversion of 

 3,920,000 acre-feet (_3) are estimated to 

 be 233,000 acre-feet between Rock Island 

 and Priest Rapids and 1,174,000 acre-feet 

 in the vicinity of Pasco. The 1950 popula- 

 tion in the Columbia River Basin above 

 Priest Rapids was approximately 700,000 

 persons C^) (_10) and the estimated future 

 population is about 1,100,000 persons by 

 the year 2000. This anticipated increase 

 in irrigation and population with its con- 

 comitant increase in industry will produce 

 future changes in Columbia River water 

 quality. 



Wenatchee River Basin 



The Wenatchee River Basin is located 

 entirely within Chelan County in north- 

 central Washington, and it has an area of 

 approximately 1,310 square miles (11) . 

 Originating in Lake Wenatchee, the Wenatchee 

 River flows southeastward for 55 miles (12) 

 to its confluence with the Columbia River 

 immediately above the City of Wenatchee. 

 It is an unregulated, rapid, snow- fed stream 

 having a mean annual flow of 2900 cf.s. 

 and a fall of 1,230 feet from Lake Wenatchee 

 to its confluence with the Columbia River 

 (11) . Principal tributaries below Lake 

 Wenatchee are Nason Creek, the Chiwawa River 

 and Icicle Creek (see fig. 4, page 6). 

 Above Leavenworth, the river basin is moun- 

 tainous and heavily forested. Below Leaven- 

 worth, the river enters a broader valley 

 that is fully utilized for fruit growing 

 (apples, cherries, apricots) and related 

 enterprises, such as box factories, packing 

 houses and storage plants. In 1950 the 

 river basin above the City of Wenatchee had 



a population of some 12,000 persons, 3,270 

 of whom were in the Cities of Leavenworth 

 and Cashmere (10). 



Water diversion for irrigation com- 

 menced on a small scale about 1870 and 

 continued until 1923, the last year of any 

 significant irrigation development. There 

 now exists 3,240 acres of irrigated land 

 along the Wenatchee River above Peshastin 

 and 25,470 acres above the river mouth (7). 

 The estimated annual depletion in river 

 discharge from irrigation usage is 50,940 

 acre-feet, which would correspond to a 

 reduction in stream flow of 170 c.f.s. for 

 an irrigation season of five months. 



Lake Wenatchee, at the head of the 

 Wenatchee River, is fed primarily by the 

 Little Wenatchee and the White Rivers. 

 Table 5 lists significant characteristics 

 of the lake. The lake is very frequently 

 subjected to the stirring action of strong 

 winds blowing down from the adjacent moun- 

 tain passes. It is normally frozen over 

 during the winter months. 



Table 5. — Lake Wenatchee 

 characteristics 



Area - square miles 

 Area - acres 



Surface elevation - average 

 Maximum depth - feet 

 Average depth - feet 

 Volume - acre-feet 

 Shoreline length - miles 

 Drainage area - square miles 

 Maximum lake discharge - C.F. 

 Minimum lake discharge - C.F. 



SOURCE OF POLLUTION 



The Wenatchee River is relatively 

 free of pollution. Significant sewage 

 dicharges axe treated prior to disposal 

 in the river. Leavenworth has a modern 

 sewage treatment plant providing secondary 

 treatment to its waste waters and Cashmere 

 has an outmoded sewage treatment plant 

 providing primary treatment _/ only. The 

 minor industrial waste discharges to the 

 river from the fruit industry plants are 



_!/ Storage for power, irrigation and flood 

 control. 



2/ Sedimentation. 



20 



