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R eservoir Storage 



Cookson Reservoir was near the full -supply level all year, with contents 

 increasing from 34 800 dam^ on January 1 to a maximum of 39 500 dam^ on 

 April 19. Elevations and contents for selected dates are given in 

 Table 2. 



Table 2 

 Cookson Reservoir Storage Statistics for 1985 



Elevation Contents 



Date (1985) (metres) (cubic decametres) 



January 1 752.149 



April 19 752.805 



December 31 752.222 



Full -Supply Level 753.000 40 900 



Storage increased during the year by 600 darn^ due to above normal 

 precipitation in the fall and base flows in Girard Creek which are 

 maintained by dewatering operations at the Poplar River Mine. These flows 

 assisted in offsetting the evaporative losses and releases from the 

 reservoir. 



On-Demand Release 



Based on the apportionment recommendations of the IJC, the United States 

 is entitled to an on-demand volume of 617 dam^ at any time from June 1, 

 1985 to May 31, 1986. As of December 31, 1985 Montana had not requested 

 this release. The on-demand volume entitlement for 1984 of 617 dam^ was 

 requested on March 26, 1985, and corrected on April 2, 1985, to be 

 delivered April 25 to May 31. This volume was delivered April 25 to 

 June 3. 



