from this study will provide a basis for 

 comparison to determine the effect of 

 impoundment on water quality, and an evalua- 

 tion of the Wenatchee River Basin in rela- 

 tion to the preservation of fish resources. 



The water quality of a region is 

 influenced by many characteristics of the 

 watershed, such as: (1) topography, (2) 

 flow characteristics, (3) geology, (4) soil 

 mantle, (5) climate, (6) land use jind vege- 

 tal cover, (7) population, (8) industry, 

 (9) ground water, and (10) irrigation. 



Water samples were collected from Nason 

 Creek, Chiwawa River, Lake Wenatchee, and 

 Wenatchee River. 



Temperature, turbidity, color, and 

 specific conductance were determined to 

 define the physical characteristics. Dis- 

 solved oxygen, carbon dioxide, pH, hardness, 

 alkalinity, sulfates, ammonia, total solids, 

 and trace metallic ions were used to inter- 

 pret the chemical quality. 



On the basis of the results of the 

 physical and chemical tests made during this 

 study, the waters of the Wenatchee River 

 Basin may be summarized as follows: 



Nason Creek . The waters of Nason Creek 

 were characterized by an extremely low con- 

 tent of suspended and dissolved matter. The 

 hardness and alkalinity was very low and the 

 pH was practically neutral. The water was 

 practically saturated with dissolved oxygen. 

 A significant diurnal variation in water 

 temperature was noted during the summer 

 months. Seasonal variations were noted in 

 most constituents. A comparison of a limited 

 sunount of chemical data collected during 

 1940 and the results of the Scime character- 

 istics noted in this study revealed no 

 changes in water quality. 



Chiwawa River . The waters of the 

 Chiwawa River were found to be extremely low 

 in suspended and dissolved matter. They 

 were consistently very low in color, tur- 

 bidity, hardness, and alkalinity, and usually 

 were saturated with dissolved oxygen. Dur- 

 ing the warm weather months considerable 

 diurncil variation in water temperature was 

 observed. 



Lake Wenatchee . The waters of Lake 

 Wenatchee were very soft, slightly acidic, 

 and extremely low in suspended and dissolved 



solids. Temperature, dissolved oxygen, 

 percent saturation of dissolved oxygen, and 

 pH all decreased with depth. Hardness, 

 alkalinity, sulfates, ammonia and total 

 solids were consistent with depth. Carbon 

 dioxide was the only constituent that in- 

 creased with depth. A brief limnological 

 study of Lake Wenatchee was maide during 

 September and October of 1939 and presented 

 an interesting comparison for the data col- 

 lected during the same two months of 1955. 

 These data revealed similar thermal strati- 

 fications in 1939 and 1955. There was a 

 slight increase in the dissolved oxygen 

 content and percent saturation at all depths 

 in 1956 as compared to 1939. This was 

 indicative of a generail decrease of the 

 biological activity in 1955 aind was corrobo- 

 rated by the lower carbon dioxide content 

 noted at that time. 



Wenatchee River . The waters of the 

 Wenatchee River are largely a mixture of the 

 flow from Nason Creek, Lake Wenatchee, 

 Chiwawa River, and Icicle Creek and there- 

 fore possess characteristics very similar to 

 those of the major tributaries. In general 

 they were very low in suspended and dis- 

 solved constituents, very soft, practically 

 neutrsil in pH and saturated with dissolved 

 oxygen. A slight downstream increase in the 

 concentrations of physical and chemical 

 characteristics was noted. A comparison of 

 the physical and chemical characteristics 

 of the Wenatchee River and the Columbia 

 River at Rock Island disclosed that they had 

 about the same amount of turbidity, color, 

 dissolved oxygen, carbon dioxide, and ammo- 

 nia. The Columbia River, in contrast with 

 the Wenatchee River, had about 2-1/2 times 

 the hardness, sdkalinity, and ionized 

 mineral content along with a higher super- 

 saturation with dissolved oxygen cUid pH. 



The impoundment of water produces some 

 important chsuiges in its physical and chemi- 

 cal qualities. These changes may be aujverse 

 to fish life, such as an increase in surface 

 water temperatures, decrease in dissolved 

 oxygen saturation with depth, increase in 

 carbon dioxide with depth, decrease of pH, 

 and the concentration of toxic elements. 

 Some beneficial effects might be a decrease 

 in suspended matter, reduction of color, 

 improvement in ssmitary quality and cooler 

 water temperatures below the dam in the 

 warm weather months. Some biological changes 

 are also involved, such as seasonal buildup 

 of plankton, change in bottom animals, 



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