Blackfoot River Basin . The Blackfoot River Basin contains 

 two identifiable regions where accumulations of valley-fill 

 sediments contain relatively large quantities of stored ground 

 water and where favorable aquifer characteristics are at least a 

 possibility. One underlies the river reach beginning ten miles 

 upstream of Lincoln and ending two miles below the town. Here 

 sediment accumulations up to 300 or more feet thick receive 

 recharge from the Blackfoot River. The existing withdrawals are 

 mainly small ones from domestic supply wells. There are a few 

 more productive wells utilizing this aquifer, and some test data 

 indicate that well yields of a few hundred gpm may be locally 

 possible (Coffin and Wilkie 1971) . Major increases in ground 

 water use would result in induced aquifer recharge from the 

 Blackfoot River and/or decreased ground water discharge to 

 downgradient gaining reaches of the river. 



The extensive glacial sediments underlying the lower 

 reaches of Nevada Creek, the North Fork of the Blackfoot, and 

 lower Monture Creek suggest that productive aquifer material may 

 exist in places. These aquifers currently supply mostly domestic 

 and stock wells and little information exists regarding the 

 potential for greater ground water uses. 



Lower Flathead Basin 



Little Bitterroot Valley . The Lonepine Aquifer (Donovan 

 1985) of the Little Bitterroot Valley stores a relatively small 

 volume of water in comparison with the regional Kalispell Valley 

 Aquifer, but it is a locally important source of irrigation, 

 domestic, and stock water. In addition, it has interesting 

 management aspects to its behavior and use. 



The Lonepine Aquifer consists of very permeable gravels 

 overlain by a massive thickness of Lake Missoula silts, which 

 provide for effective aquifer confinement and artesian flow 

 conditions. Most large withdrawals from the aquifer are from 

 flowing wells used for irrigation and for supplying a commercial 

 resort dependent on the geothermal flows that contribute recharge 

 to the Lonepine system. Approximately 1,130 AF/year currently 

 flow past the area of irrigation use (eventually reaching the 

 lower Flathead River or shallow alluvial aquifers) . Pumping from 

 the aquifer could allow for the capture of more of this through- 

 flowing water and probably would induce additional aquifer 

 recharge from the Little Bitterroot River. However, large 

 additional withdrawals are not compatible with the maintenance of 

 flowing wells in the area. Additional development could force 

 the replacement of existing irrigation systems and the adoption 

 of new modes of operation by the current water users. 



4-20 



