Reservoir Storage 



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

 from an elevation of 752.320 metres (m) on January 1 to a maximum 

 water level of 752.836 m on April 15. Elevations and volumes of 

 stored water for selected dates are given in Table 2. 



Table 2. Reservoir Storage Statistics for 1984 



Elevation Volume 



Date (1984) (metres) (cubic decametres) 



January 1 752.320 38,300 

 April 15 752.836 42,200 

 December 31 752.149 37,000 



Full-Supply Level 753.000 43,400 



Storage decreased during the year by 1 300 dam-^, and would have de- 

 creased even more during the hot and dry summer if base flows in 

 Girard Creek had not been maintained by dewatering operations at the 

 Poplar River Mine. These flows assisted in offsetting the evapora- 

 tive losses and releases from the reservoir. Based on present condi- 

 tions, most of the predicted runoff for 1985 can be stored in 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, 1984 to May 31, 1985. As of December 31, 1984 Montana 

 had not requested this release. The on-demand volume entitlement for 

 1983 of 370 dam^ was requested on April 10, 1984 to be delivered 

 April 15 to May 15. This volume was delivered April 16 to May 24. 



