The Upper Subbasin provides important spawning grounds and year round rearing habitat for anadromous salmonids. High water temperature and a shortage of deep, complex pool habitat are factors limiting salmonid production in the mainstem Redwood Creek below Minon Creek. The lack of deep and complex pool habitat was also identified as potential limiting factors in tributary streams.
The Upper Subbasin was severely affected by the combination of intensive land use activity and the 1964 and other recent flood events. The channel more than doubled in width and shade benefits of riparian vegetation and moderating air temperatures from near stream forests were lost leading to increased water temperatures. Habitat impairments associated with channel widening and high stream temperature still adversely effect habitat suitability throughout much of the upper Redwood Creek mainstem.
While habitat conditions certainly differ from those of pre-management days, it does appear that aspects of the upper mainstem have recovered from the impacts of land management and floods. Much sediment has moved downstream, pools have re-formed and the channel substrate has improved in spawning suitability. However, excessive erosion continues to be a problem as the Upper Subbasin currently yields more suspended sediment to the mainstem of Redwood Creek than the Middle and Lower subbasins combined.
The upper Subbasin offers good opportunities for implementing watershed improvement activities. Watershed management strategies aimed at reducing sediment inputs by reducing erosion will help address landscape issues that contribute to impairment of aquatic habitat. Stream habitat improvement projects should focus on preserving cool water flowing from the headwaters reach of Redwood Creek re-establishing riparian shade and reducing the channel width along mainstem Redwood Creek. Restoration projects such as tree planting and adding LWD and shelter complexity to stream channels may increase the rate of stream recovery. Adding shelter complexity to cool water refuge sites will provide summer steelhead protective cover needed during their summer holding stage. In tributary watersheds, stream habitat improvement activities should focus on increasing frequency, depth and complexity to pool habitats, adding instream shelter complexity, and promoting nearstream coniferous forest growth retention.