dissolved substances, turbidity, and color, Tab 



over that observed in 1910-11 because of (weighted 



soil tilling, removal of natural vegetative values fo 



covering and because of the addition of Values we 



deciduous tree leaves that impart color to where dat 



water. periods. 



Table 31. — Weighted-average constituent values 

 in the Wenatchee River, 1910 and 1954-57*. 



* Weighted according to flow for average-monthly 

 values shown in table 30. 



_1/ Less months of February, April cind May. 



2/ For March, April, May and June only. 



le 31 gives the weighted-average 

 according to flow) constituent 



r these two comparison periods. 



re weighted only for those months 



a were available during both 

 Percentage increases were: total 

 I alkalinity 43; total hardness 

 26; total solids 62; calcium 

 plus magnesium 19; sodium plus 

 potassium 0.0; color 125; tur- 

 bidity 14; and iron 0.0 percent. 

 Sulfate decreased by 71 percent. 

 The reduction in sulfate may 

 be due to a difference in test 

 technique or it may be due to 

 high sulfate values in 1910-11 

 when rapid leeching was taking 

 place in newly irrigated lands. 



Weighted-average constit- 

 uent values are obtained by 

 multiplying the average-monthly 

 discharge for the times of 

 sampling by the average values 

 of the individual constituents 

 for the month and dividing the 

 year's sura of these products 

 by the total discharge for the 

 year. These weighted-average 

 values are affected by high- 

 flow periods as dissolved con- 

 stituents are usually low 

 during period of high discharge. 

 Thus, we ighted-aver age constit- 

 uent values will show lower 

 concentrations than those values 

 obtained by averaging the 



Table 32. — Comparison of constituents discharged by Wenatchee 

 River in 1910-11 and 1954-57, 10^ tons/year. 



At Cashmere 

 1910-11 



Near mouth 

 1954-57 



Total alkalinity 



Sulfate 



Ca + Mg y 



Na + K -^ 



Total solids 



iron y 



Total hardness 



84.78 

 31.21 

 16.16 



8.43 

 237.9 



0.044 

 91.94 



124.11 



9.57 



24.85 



10.92 



352.1 



0.043 

 127.4 



1/ Less months of February, April and May. 



110 



