SURFACE WATER QUANTITY 



Natural Flow 



The natural flow in the Poplar River basin was well above normal in 1982, 

 assuming the recorded flow of the Poplar River at International Boundary is 

 a good indicator of basin runoff conditions. Snow accumulation prior to 

 runoff was above normal, and combined with a late melt and rapid warming, 

 resulted in a maximum instantaneous discharge of the Poplar River that was the 

 5th highest on record; 113 cubic meters per second (m /s) on April 13, 1982. 



The volume of runoff in the Poplar River between March 1 and October 31, 1982 



was 29,500 cubic decametres (dam ) compared to a long term mean volume of 



3 

 17,200 dam . The recorded runoff volume of the Poplar River during the March 1 



to May 31 period, used as an indicator in setting the minimum and on demand 



releases in the East Poplar River under the International Joint Commission 



apportionment recommendations, was 27,^00 dam . 



Minimum Flows 



Based on the apportionment recommendations of the International Joint Commission, 



the United States would be entitled to a minimum discharge of 0.028m /s from 



3 3 



January until May 31; O.O85 m /s from June 1 until August 31; and 0.057 m /s 



from September 1 to December 31, 1982 on the East Poplar River at the Inter- 

 national Boundary. This stream regime is designed to enhance instream environ- 

 mental values during the summer period in years when spring runoff is high. 



The minimum discharge in the East Poplar River during the period January 1 to 



■J 

 May 31 was 0.023 m /s, with this flow occurring from January 16 to January 25. 



During the January to May period the recorded flow was marginally below the 

 recommended minimum flow for 46 days, all under ice conditions. Cold tempera- 

 tures during this period caused large accumulations of ice in the channel 

 between Cookson Reservoir and the International Boundary which reduced flows 

 to less than what had previously been measured. The flow was below the recom- 

 mended minimum for 2k days in August when a discharge of 0.076 m /s was recorded 

 on August 6 and August 9 to 31. The minimum flow during the period September 1 



