into streams, springs, seeps, and drains; and pumping from 

 wells (Konizeski et al. 1968). 



In the Missoula Valley (Missoula to Huson) , the geology 

 generally consists of a bottommost layer of Precambrian 

 metasediments; a middle, thick (about 2,000 feet) layer of 

 Tertiary sediments; and a thin (less than 200 feet) layer of 

 Tertiary to Quaternary coarse sand and gravel that is 

 exposed at the surface on the valley floor. 



Although all three are water-bearing formations, the 

 upper layer (called the Missoula Aquifer) is by far the most 

 productive and is the major source of ground water in the 

 valley (Missoula City-County Health Department 1987) . 



The Missoula area depends heavily on the Missoula 

 Aquifer for its water. The primary source of drinking water 

 for Missoula Valley residents, the aquifer also supplies two 

 municipal water systems, many small community water systems, 

 several large industrial users, and private well owners. 

 Stone Container Corporation's pulp mill is the largest 

 individual water user in the area, with a pumping rate of 

 24.5 million gallons per day from 12 large wells. Other 

 sources of discharge from the aquifer include evapotranspira- 

 tion and base flow to the stream (Missoula City-County Health 

 Department 1987) . 



Sources of recharge to the Missoula Aquifer calculated 

 by the Missoula City-County Health Department are: over 50 

 percent from streams that lose water to the aquifer (the 

 Clark Fork alone provides 46 percent of the annual recharge) , 

 24 percent from lateral flow from adjacent sediments, and 

 smaller amounts from precipitation, urban storm water runoff, 

 septic system drainfields, and irrigation and Water line 

 leakage. The Clark Fork loses water to the aquifer over a 

 three-mile segment. 



MINING 



Gold was discovered in the upper Clark Fork drainage in 

 the early 1850s, although it was not developed until the 

 early 1860s. The most successful diggings were located at 

 Gold Creek, Butte, Bearmouth, and in the Little Blackfoot 

 River drainage. Although placer operations in the upper 

 Clark Fork were never major producers, these activities led 

 to the discovery of the silver and copper veins that shaped 

 the later history of this region (Horstman 1984) . 



As placer operations expanded, the demand for water to 

 work the diggings increased, leading to the organization of 

 independent water companies. Flumes and ditch systems were 



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