1 . STREAM 

 Twelvemile Creek 



2. DESCRIPTION 



Twelvemile Creek originates on the east slope of the Anaconda-Pi ntlar 

 range at the Continental Divide. The stream flows in a southerly direction 

 for approximately 9.4 miles to its confluence with Deep Creek, a tributary 

 of the Big Hole River. The only major tributary of Twelvemile Creek is the 

 West Fork of Twelvemile Creek. The 10 square mile drainage area is characterized 

 by high alpine meadows with numerous small lakes, timbered ridges and slopes, 

 and broad willow bottoms as elevation decreases. The stream drops rapidly 

 through coniferous forests in the upper reaches and meanders through a broad 

 willow-grass-sedge- riparian zone in the Deep Creek floodplain. The lower 

 willow bottoms are characterized by numerous beaver ponds. The average 

 gradient of the 9.5 foot wide channel is 56.4 feet per 1,000 feet. Ownership 

 majority of the Twelvemile Creek drainage is controlled by the USPS while a 

 smaller portion is controlled by the MDFWP. 



Lands within the Twelvemile Creek drainage are used for recreational 

 hunting, fishing, trapping, and winter sports. Lower portions of the drainage 

 contain important moose winter range and an elk calving area. No estimate of 

 fishing pressure is available for Twelvemile Creek; however, some fishermen use 

 was observed during the summer of 1980. Past commercial uses of the drainage 

 include livestock grazing, timber harvest and diversion of water for irrigation. 

 Present commercial uses include cattle grazing and timber harvest. 



Chemical analyses were performed on water samples collected from Twelve- 

 mile Creek during the summer of 1980. The data revealed that the stream has 

 excellent water quality marked by very low specific conductance, alkalinity, 

 hardness, suspended sediment and concentration of dissolved ions. The stream 

 is a weak calcium-sodium-bicarbonate water of nearly neutral pH. 



The streambank and riparian zones of Twelvemile Creek are relatively 

 stable and in good condition. Activities that could impair water quality and 

 damage habitat include timber harvest in the upper drainage and cattle grazing 

 along the lower reaches of the stream. 



3. FISHERIES 



A 1,000 foot section of Twelvemile Creek was electrof ished on August 6 

 and August 20, 1980. Game fish captured in descending order of abundance were 

 brook and rainbow X cutthroat hybrid trout. Mottled sculpin were the only non- 

 game species collected. Electrof ishing survey data are summarized in Table 28. 



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