49 



fish production in ungrazed streams ranged from 2.4 to 5 times 

 greater than grazed streams. 



Mining - This activity may increase sediment transport and 

 deposition (erosion), decrease stream flows, change stream 

 geomorphic form, decrease vegetative cover, change pH, mobilize 

 toxic heavy metals and increase water pollution. Some past 

 mining activities had devastating effects on salmon and steelhead 

 habitat, altering the streambed and leaving the channel 

 unsuitable for anadromous fish. Areas in Idaho, such as Panther 

 Creek, upper Southfork Clearwater River, and Bear Valley Creek 

 still exhibit degraded habitat caused by earlier mining. 



Hydropower - Proposed hydroelectric projects on public lands may 

 reduce and adversely affect available habitat for anadromous fish 

 as a result of blocked or limited access, inundation, water 

 withdrawal and degradation associated with construction. 



Habitat alteration for enhancement - The effectiveness of methods 

 to enhance anadromous fish habitat is mixed. While some 

 successes have been noted, these structures can fail, causing 

 damage to the streambed or alteration of stream flows. Such 

 structures include weirs, deflectors, boulder placement, cover 

 structures, bank stabilization and the construction of side 

 channels and ponds. 



