Reduced water quality has a significant effect on 

 recreation and aesthetics. Excessive algae growth, suspended 

 solids, and color are water quality conditions that directly 

 affect aesthetic quality. Residents of the Clark Fork Basin 

 have complained that foam, scum, algae growth, and sediments 

 have increased in the middle and lower segments of the river. 

 Idaho residents have complained of algae and bacterial scums, 

 especially in near-shore areas surrounding docks and beaches. 

 These physical and visual impacts of reduced water quality 

 are important but they are seldom quantified or measured 

 directly. Often these problems are the indirect result of 

 other, more basic water quality conditions. 



Effects from Existing Hydropower Development 



Historically, the Clark Fork was a major spawning 

 ground for fish migrating out of Lake Pend Oreille, Idaho. 

 Some historical records suggest that fish may have travelled 

 as far upstream as Missoula, a distance of 211 miles from 

 Lake Pend Oreille (Malouf 1974) . The three dams on the lower 

 Clark Fork modified the habitat and blocked access to 

 spawning grounds for fish migrating out of the lake. The 

 Thompson Falls Dam, constructed in 1916, blocked migrations 

 for all but the lower 70 miles of river, and the Cabinet 

 Gorge Dam, constructed in 1953, eliminated the remaining 

 fishery for migratory westslope cutthroat trout, kokanee 

 salmon, and bull trout (a fish ladder was constructed at the 

 Thompson Falls Dam, but information regarding its usefulness 

 is lacking) . 



Each of the lower river reservoirs is a run-of-the-river 

 impoundment, constructed for the primary purpose of hydro- 

 electric power production. The operations of the power 

 plants, including drawdowns and the physical characteristics 

 of the reservoirs, combine to create adverse conditions for 

 fish production. The relatively rapid water exchange, or 

 flushing rate, in each reservoir limits the plankton 

 production needed to sustain greater fish populations. Fish 

 food availability (aquatic insects and other benthic 

 organisms) are also severely affected by water level 

 fluctuations and reservoir drawdowns. Spawning beds within 

 the reservoir and access to tributary spawning areas may be 

 severely diminished depending on the timing of reservoir 

 drawdowns and the onset of spawning. Testing has also shown 

 that large numbers of fish species predisposed to migrate 

 (i.e. rainbow) are flushed downstream during spring runoff. 



During the period of 1953 to 1963, large numbers of 

 trout and kokanee salmon were stocked in Cabinet Gorge 

 Reservoir, but a self-sustaining fishery was not established. 

 Since 1963, fish stocking in Cabinet Gorge has been suspended 



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