Lake Wenatchee 

 Tables 21 and 22 : 



Table 21 (page 70) gives the water 

 quality constituents observed with depth by 

 the University of Washington from June 1955 

 through February 1957. Table 22 (page 76) 

 gives the constituent values observed with 

 depth by the U. S. Fish and Wildlife Ser- 

 vice in September, October and November of 

 1939. The U. S. Fish and Wildlife Service 

 and the University data compare very closely. 

 Dissolved oxygen saturation values have not 

 been corrected for altitude and the new 

 solubility values. Therefore, each satura- 

 tion value should be increased by about 9 

 percent, making most of the shallow samples 

 saturated with dissolved oxygen. 



The hydrogen-ion concentration (pH) 

 is less than 7.0 (acidic) most of the year. 

 Alkalinity was all bicarbonate (HCO^-) and 

 never exceeded 16 mg/1 as CaC03. Both 

 carbonate and non-carbonate hardness were 

 observed with carbonate predominating. Total 

 hardness was usually less than 15 mg/1 as 

 CaCXDo. The water is clear, its color ex- 

 ceeding 10 only once and its turbidity was 

 usually less than 10. Total solids were 

 normally under 50 mg/1. Table 27 summarizes 

 tables 21 and 22 by listing the minimum, 

 average and maximum constituent values ob- 

 served at different depths throughout the 

 sampling period. 



WATER TEMPERATURES 



Strong winds blowing over the lake 

 tend to keep the water well-mixed with depth. 

 The only significant quality change with 

 depth is that of temperature. Stratifica- 

 tion, as determined by temperature measure- 

 ments, occurred only in the late summer and 

 autumn. (See section following on tempera- 

 ture observations.) Lake Wenatchee is a 

 typical oligothrophic lake that is low in 

 dissolved mineral matter, has a continuous 

 abundance of dissolved oxygen and has cold 

 water in its greater depths throughout the 

 year. 



Tables 24 and 25 (pages 86 and 90) 

 present water temperature data in the sur- 

 vey area. Table 24 lists average-monthly 

 water temperatures computed from thermo- 

 graph records of the U. S. Fish and Wildlife 

 Service and of the Chelan C ounty P.U.D. The 

 average temperature is taken as the average 

 of the daily maximum and minimum tempera- 

 tures. Thermographs at Pasco, below Grand 

 Coulee Dam, the mouth of the Snake River 

 and the mouth of the Yakima River are oper- 

 ated for only a portion of each year. 

 Diurnal temperature variations (as shown 



Table 27. — Lake Wenatchee, minimum, average and maximum constituent values 

 with depth in milligrams per liter. June 1^55 - February 1957. 



* Single observation - Ca and Mg values appear in error. 



94 



