the BOR's more detailed estimates. Using the same assump- 

 tions about the location of developments, depletions, and 

 electric rates, there was only a 20 percent difference in 

 the calculation of losses ($7.84 vs. $6.5 million). 



The potential for storage at Hungry Horse to mitigate 

 these losses was found to be limited. The BOR study found 

 that, while total generation within Montana could be 

 restored, there was great disparity in gains and losses at 

 each of the hydropower plants. There were substantial 

 generation gains at Kerr Dam (MFC) resulting from releases 

 from Hungry Horse, but the effect at Noxon Rapids (WWP) could 

 not be mitigated. This is because Noxon Rapids has the 

 capacity to use almost the entire annual flow of the Clark 

 Fork. Using storage to reshape the timing of these flows 

 increases generation at Kerr by making flows usable that 

 might otherwise exceed plant capacity and be lost to spill. 



Furthermore, the BOR points out that there would be 

 significant impacts associated with changing the operation of 

 Hungry Horse Reservoir. "An increase in winter releases 

 would increase the risk that Hungry Horse would not refill in 

 the spring. This could affect the reservoir fishery and 

 recreation use. Additional restrictions on Hungry Horse may 

 cause other headwater projects in the Columbia River system 

 to be drafted more heavily in the coordinated system 

 operation, as the Northwest utilities reformulate their 

 system operation to maximize the FLCC based on new deplistions 

 and contractual constraints." 



MUNICIPAL WATER SUPPLIES 



Public water supplies in the Clark Fork Basin are 

 derived from a number of sources. The majority of the 

 communities use ground water as their primary source of 

 water, but a few rely heavily on tributary surface water* 

 In the Missoula area, the public water supply is obtained 

 primarily from the Missoula Aquifer, which is partially 

 recharged by the Clark Fork. An inventory of municipal water 

 supplies in the basin is provided in Table 2-11. 



The DHES-WQB administers the Safe Drinking Water Act, 

 and, in conjunction with public utilities, it monitors these 

 public water supplies to insure that bacterial, chemical, and 

 radiological contents remain within safe limits. WQB 

 personnel review and approve all construction and modifica- 

 tions to public water systems and conduct annual inspections 

 of each system. 



2-18 



