Table 1. — Mean water iemperalure and mean volume of 

 flow from the Snake River into Brownlee Reservoir and 

 discharge at Brownlee Dam, May 1962 to June 1964 



' Courtesy of Bureau of Commercial Fisheries, River Basins Studies, 

 Boise, Idaho. 



of 1962 was relatively minor — only 6.4 m. ; fill-up 

 was short in 196;] and was completed by early May. 

 As a result, the triermoclinc was formed fully 2 

 months earlier than in 1962. 



OXYGEN CONCENTRATIONS 



The cliroiiolog-ieal changes in oxygen concen- 

 trations pei-mit description of seasonal changes 

 and estimates at particular times (fig. 5). 



Seasonal changes are described best by starting 

 with Januai-y 196.", when dissolved oxygen con- 

 centrations approached saturation throughout the 

 reservoir at all tlejiths; conditions changed little 

 until March when some decrease was evident below 

 4;» m. Concentrations by May dropped to 1 p.p.m. 

 on the bottom at stations 14 and 15, where the res- 

 ervoir first receives a deposit of silt from the Snake 

 Kiver. Oxygen content of the entire resei-voir 

 ranged between 1 and 7 p.p.m. 



Oxygen depletion continued at the lower depths 

 from May until November when turnover began. 

 The oxygen content near the surface ((>-15 m. ) 

 increased in some areas, however, and generally 

 ranged from 4 to 13 p.p.m. Increase of oxygen at 

 the surface was presumably due to algae, which 

 wei'e readily \isible throughout the reservoir. Ivow- 

 est concentratiiins of oxygen came in August, when 

 all w;»ter below 2.") ni. had a concentration of 3 



Table 2. — Air temperature at Weiser, Idaho,' and on west bank at station 14, Brownlee Reservoir, June 1962 to June 1964 



1963 



Locality and month 



Average Average Average Average Average Average 

 maximum minimum median maximum minimum median 



'C. "C. °C. °C. °C. °C. 



Weiser, Idaho: 



January. 1.3 —8.5 —3. 3 



February... 10.4 -.8 4.8 



March 13.6 -.7 6.4 



April 15.4 1.8 8.6 



May. 23.9 6.6 16.2 



June 29.2 9.4 19.3 26.6 9.6 17.6 



July 32.2 13.3 22.7 31.6 9.5 20.6 



August 30.2 11.4 22.7 32.8 11.2 21.9 



September 26.6 6.8 16.7 28.7 9.2 19.0 



October 17.8 2.9 10.3 20.6 3.7 12.1 



November 10.1 -.6 4.8 9.9 -.8 4,6 



December 4.6 -2,2 1.2 .6 -7.6 -3.6 



Station 14, Brownlee Reservoir: 



January 



February 12.4 1.9 7.2 



March 13.9 2.1 8.0 



April 16.7 3.6 10.1 



May 25.1 10,5 17.8 



June 27.3 12,9 20,1 



July 34.2 16,2 25.2 



August 34.5 18.4 26.4 



September... . 28.8 15.2 22.0 



October 22.2 17.9 20.1 



November... 1L3 3.1 7.2 



December.. 3.0 —2.8 .1 



' Courtesy of radio station KWEI. 

 304 



U.S. FISH AND WILDLIFE SERVICE 



