Burlington Northern Railroad and Interstate 90 trans- 

 portation corridors (transportation of hazardous 

 materials and wastes) 



Because the Clark Fork provides 46 percent of the total 

 recharge to the Missoula Aquifer, surface water quality of 

 the Clark Fork is obviously very important. Upstream 

 activities in the streamflow source area are of major 

 concern, although there is a decreasing gradient of potential 

 impact to the aquifer from surface water contamination in the 

 upstream direction (MCCHD 1987) . The petitioners have 

 defined the project review area as the designated area and 

 the portion of the streamflow source area within a 15-mile 

 radius of Missoula. This represents the area where major 

 development projects would likely have the greatest effect on 

 the quality of the Missoula Aquifer. 



Lower Clark Fork Basin 



Little information has been published on ground water 

 quantity or quality in the Clark Fork drainage basin between 

 Huson and the Montana-Idaho border. The lack of knowledge 

 regarding the ground water resources in the lower drainage 

 basin suggests that it might be prudent to conduct at least a 

 reconnaissance ground water study of the area, particularly 

 in light of the potential mining development in this portion 

 of the basin. Recommendations for ground water studies are 

 outlined in Chapter 5. 



FISHERIES, RECREATION, AND AESTHETICS 



Effects of Surface Water Quality Degradation 



In the mainstem Clark Fork, trout populations appear to 

 be affected by a variety of water quality factors, including 

 dewatering, elevated temperatures, excessive nutrients, and 

 siltation. However, the major factor suppressing trout 

 populations appears to be metals. 



Recruitment of brown trout to the mainstem Clark Fork 

 above Milltown Dam is limited primarily to tributaries and 

 perhaps the river itself in the Warm Springs area. Among the 

 tributaries currently known to support major spawning runs 

 from the river are Warm Springs, Gold, and Rock creeks, and 

 the Little Blackfoot River. The contribution from Flint 

 Creek is currently unknown but will be assessed in the 

 future . 



3-113 



