Coho salmon are listed as a candidate species, and coastal cutthroat are proposed for a threatened listing. Mayfield, Mossyrock, and Cowlitz Falls dams form complete barriers to natural upstream migration and inhibit downstream migration. Over 300 miles of formerly productive habitat is either inaccessible or inundated by the reservoirs. Almost throughout WRIA 26, LWD abundance is below habitat standards. Adequate large woody debris in streams, particularly larger key pieces, is critical to developing pools, collecting spawning gravels, and providing habitat diversity and cover for salmonids.
Riparian conditions are also poor within most of the basins.
Loss of riparian function affects water quality, erosion rates, streambank stability, and instream habitat conditions. Water quality, especially high water temperatures, was identified as a major limiting factor within certain subbasins of WRIA 26. Both low flows that limit the rearing habitat and connectivity, and increased peak flows that alter instream habitat were considered significant problems in many subbasins. Most of the historic off-channel and floodplain habitat has been disconnected from the river by diking and hardening the channels and due to the 1980 eruption of Mount St. Helens. Continue to monitor the impacts of the operation of the dams on salmonids and the success of the reintroduction efforts above the dams.