The building of the dams and hydro projects at Clowhom, can be compared with the Enloe Dam in Washington State, good for power, disastrous for fish.
The loss of fish habitat at Clowhom was an issue in the eighties when I lived and worked here, and it is still an issue now. I am trying to learn more about the situation, and will inform you on what I can find.
My Native friends say there was an important sockeye run, and several other anadromous fish species in the old Clowhom.
http://www.bchydro.com/bcrp/about/docs/ch14_final.pdf a comprehensive report
2.1 Historic and Current Species Presence
Table 14-1 lists the species currently found in major reaches of the Clowhom River basin.
2.1.1 Upstream of Clowhom Dam
An extensive sport fishery for rainbow and cutthroat trout existed in the original lakes from 1927 to 1956 (Keller & Leslie 1996). A fishing lodge continues to operate (BC Hydro 1994). The pre-impoundment lakes were judged to be unproductive due to their depth and the lack of benthic organisms and observable plankton (Smith and Larkin 1950).
The upper Clowhom River has extensive spawning gravels (Smith and Larkin 1950; B.C. Game Commission 1956; J. Stephen, Conservation Officer, field notes). Most reservoir tributaries are presently limited in habitat quality due to steep gradients, coarse substrates, obstructions, and low summer flows (Lewis et al. 1996). Some tributaries, e.g., Red Tusk Creek, have been used as spawning habitat but species were not specified (Hirst 1991b).
2.1.2 Downstream of Clowhom Dam
Archival information indicates the absence of anadromous fish in the Clowhom basin in the last century, at least in large or consistent numbers. A small side channel existed prior to initial dam construction in 1950 that reportedly enabled coho salmon and steelhead to ascend the falls and possibly contained some spawning and rearing functions (workshop).