TABLE 3-31, 



INVENTORY OF DAMS BY COUNTY WITH 50 AF 

 OR MORE CAPACITY IN THE CLARK FORK BASIN 



County 



No . Dams 



No. Used for Irrigation 



1 



14 

 

 11 

 11 

 23 

 2 



Total 



80 



67 



Source: Montana Water Resources Board 1968. 



Ravalli County has the highest number of small storage 

 projects, which were constructed many years ago. Most lie on 

 the west side of the Bitterroot Valley. Almost all of them 

 utilize existing high mountain lakes in the Selway-Bitterroot 

 Mountains. Dams were built on the outlets to store addition- 

 al water for late-season irrigation use. 



The impacts of these small projects is not completely 

 known. Many of the mountain lakes provide fishing for 

 persons who hike into them, as many are in roadless and 

 wilderness areas. Dams at some lakes have been breached for 

 safety reasons, creating water too shallow for fishery 

 production. Other dams are still in place but unused, and 

 the higher water levels of those lakes produce better 

 fisheries. Lakes with adequate depth provide moderate 

 fishing opportunities for various trout species. There is 

 minimal natural reproduction in inlet and outlet streams in 

 some lakes, and most are maintained by periodic stocking. 

 These lakes are extremely aesthetic, but drawdowns detract 

 from this pleasantness in some cases. 



Because the projects store snowmelt and the stored 

 water is released after spring runoff, there is probably a 

 beneficial effect on the flow of tributary streams in late 

 season, at least up to the first point of diversion. 

 However, most of these tributaries are partially or totally 

 dewatered by the time they reach the Bitterroot River. 

 Return flows from use of the stored water may help hold up 

 flows in the lower Bitterroot. 



3-126 



