In Iron may be the result of anaerobic 

 decomposition at the resrrvolr bottom vltb 

 the resulting increase in Iron solutlbllity 



Yaklaa River at Prosser and Klona , 

 Figures ^6 and ^7, Table 22 l 



The U. S. Geological Survey water 

 quality samples collected in I9IO-II were 

 taken frcm the Yakima River at Prosser 

 while those collected in 1953-5^ were at 

 Kiona, I6 miles downstream from Prosser. 

 There are no tributaries of any signifi- 

 cance between these stations. During the 

 irrigation season, return flows from the 

 Roza project enter the river between these 

 stations . 



Between I9IO and 19^0, the wai^rshed 

 population increased by 12U percent, the 

 irrigated acreage by I3I percent and an 

 industrial waste population equivalent of 

 138,C)00 persons was euided to the river. 

 River flow was regulated for irrigation 

 purposes by the construction of the Keeche- 

 lus, Kachess, Cle Klum, Bumping, and Tleton 

 Reservoirs, Impounding a total of l,06l4-,000 

 acre -feet. 



On comparing the I9IO and 19^^*^ qual- 

 ity data, it will be observed that all 

 constituents have increased diuring the 43 

 year period excepting for sulfate, color 

 and iron which have decreased. The larg- 

 est increases occiirred in the late sunner 

 and autumn when irrigation return flows 

 were greatest. Nitrates and alkalinity 

 showed an Increase for all months. 



Ccmparlng quality values in the two 

 time periods and using weighted averages 

 to compensate for the heavier flow in I9IO- 

 11, the percentage increase in the con- 

 stituent was as follows: Alkalinity - 55; 

 hardness - 3^; silica - 28; dissolved 

 solids - 27; calcium plus magnesixjm - 38; 

 sodiiim plus potassium - k3} chlorides - 52; 

 and nitrate - 6hO. SvLLfate decreased 23 

 percent and iron 700 percent. The effect 

 of irrigation on water quality is discussed 

 in a subsequent chapter of this report. 



Deschutes River at Moody , 

 Figures 58 and 59, Table 23 ; 



The Deschutes River has been control- 

 led for power and irrigation development by 



Table 22. — ^Water quality comparison. 

 Takima Riirer at Prosser, 1910-11 (U.S.G.3.) 



In P. P.M. 



Jan. 



Feb. 



Mar. 



J\me 



July 



Sept. 



Oct. 



Not. 



Dec. 



Each sample represents composite of 10 or more daily samples. 



As p.p.B. CaCOj. 



Computed from Ca * Hg as CaOO,. 



16 miles downstream from ProsSer. 



81 



