22 



TOO 



600 



PREIMPOUNDMENT 



1000 

 900 



m 800i 



< 



5 70 ° 



5 



v 600 



z 



I 500 



< 400 



> 



300- 



200- 



100 



F M A 



* 



POSTIMPOUNDMENT 



/ 



\ 



\ 



\ 



FIGURE 2. Average monthly discharges (cfs) + 1 standard deviation in 

 the Beaverhead River at the U.S.G.S. gage near Twin Bridges 

 before impoundment (1951-63 water years) and after impound- 

 ment (1965-75 water years). 



* 



