WATER TEMPERATURE 



Maximum daily water temperatures equaled or exceeded 70 F at 

 each of the three stations where temperature was monitored 

 (Figure 5) . The influence of the North Fork of the Blackfoot 

 River (RM 54.1) on temperatures in the Blackfoot River are 

 apparent at Scotty Brown Bridge (downstream 8.5 miles) where 

 temperatures were 4 to 5 F less than at Raymond Bridge (6 miles 

 upstream from the North Fork) . Water temperatures monitored near 

 Belmont Creek (32.2 miles below the North Fork) were more similar 

 to temperatures at Raymond Bridge than at Scotty Brown Bridge. 



Water temperatures greater than 68 F are generally 

 considered to be above the optimal level for salmonid growth. 

 From mid-July to late August, maximum daily water temperatures 

 exceeded 68 F at the Raymond Bridge, Scotty Brown Bridge, and 

 Belmont Stations 38, 11, and 44 days, respectively. 



Despite low streamflow levels, spot checks of water 

 temperatures in reaches 1 and 2 did not detect temperature 

 problems in 1988. Significant groundwater inflows in these 

 reaches appear to moderate water temperature. 



Water temperatures in the Clearwater River are significantly 

 influenced by the Clearwater chain of lakes. Warm water leaving 

 these lakes during 1988, however, was largely diverted for 

 irrigation near highway 200. Water remaining near the mouth of 

 the Clearwater River primarily originated from groundwater 

 recharge. Consequently, the Clearwater River did not elevate 

 water temperatures of the Blackfoot River as expected. 



Low stream substrate temperatures resulting in anchor ice 

 (ice formed on the stream bottom) in the Raymond Bridge area were 

 observed in late November, 1988. In December, 1988 an estimated 

 90% of the Raymond section had anchor ice. Anchor ice occurred 

 in pools, runs and riffle areas. 



TROUT POPULATIONS OF THE BLACKFOOT RIVER 



The Blackfoot river possesses a diverse wild trout fishery. 

 Species composition throughout the river varies greatly 

 depending upon location within the drainage. Cutthroat and brook 

 trout dominate the headwaters, followed by several miles of brown 

 trout fisheries, and finally becoming a trout fishery dominated 

 by rainbow trout in the lower two reaches (Table 2) . 

 Accordingly, results from fish sampling have been arranged to 

 address distinct river reaches, which were identified based on 



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