The month of sample collection is indicated 

 in the table. Table C in the appendix 

 lists the average monthly values of the 

 constituents at each station together with 

 the year or years of sampling. Figures 12 

 through 25 illustrate the principal con- 

 stituent variations at representative loca- 

 tions in the Columbia River Basin. 



GenereLL: With the exception of the Willa- 

 mette River, all streams s£unpled had an 

 abundance of dissolved oxygen. Supersatu- 

 rated conditions were frequent during the 

 summer when phytoplankton activity was high. 

 Dissolved oxygen values as low as 2.8 p. p.m. 

 were observed in the lower Willamette River 

 during August. The Snake, Unatilla and 

 lower Yakima Rivers together with Crab and 

 Rocky FordCreeks differ markedly from the 

 other streams sampled because of their 

 relatively high content of dissolved mate- 

 rial, high summer eilkalinities and because 

 of their high summer water temperatures. 

 The Snake River has a meirked influence on 

 the Columbia River water quality below 

 Pasco. 



O Y- 



FEe yAR VR MAT JUN 



lUG SEP OCT NOV DEC. 



Trace elements tested for were low. 

 Lesui and silver were not found at any 

 sampling station. Manganese was obseirved 

 in trace quantities only on the Lewis 

 River below Merwin Dam. Traces of copper 

 were found occasionally at several sampling 

 stations as was zinc and eiluminum. 



Columbia River: Figure 12 is a monthly 

 average plot of selected and constituents 

 below Coulee Dam. Minimum values lag the 

 period of high runoff by about two months 

 because of the large storage in Lake 

 Roosevelt and in the Ceinadian lakes £ind 

 impoundments. The yearly fluctuation in 

 constituents is relatively low because of 

 the leveling-off or evening-out effect of 

 the impoundments which mix the inflowing 

 waters. Figure I3 is a similar plot for 

 the Columbia River at Maryhill, 85 miles 

 below McNary Dam. The yearly range in 

 constituent values fluctuate far more than 

 at Grand Coulee and they more closely 

 follow the rate of river discharge in an 

 inverse relationship. Maximum constitu- 

 ents are in the autumn when the river flow 

 is low. 



COLUMBIA RIVER AT GRAND COULEE 



AVERAGE MONTHLY VALUES — YEARS 1950 - 1951 



rt» HAR ARR HAT JUN JUL AM SIR OCT NOV OCC 



COLUMBIA RIVER AT MARYHILL 



AVERAGE MONTHLY VALUES — YEARS 1952 " 1953 



USGS DATA 

 FIG. 12 



uses. DATA 



FIG. 13 



?s 



