Long Range Plan For The Klamath River Basin ... - KrisWeb

watershed was considered in 1980 to be at the point where increased stormflow peakscould result, "with implications for bank erosion and aggradation downstream" (Coatsand Miller 1981).Such aggradation did result and was obvious in Turwar Creek in 1989 (Caltrans1989, S. Downie personal communication). In the lower section, streamflow now goessubsurface during late summer and fall, blocking access to fall chinook and possiblyother species. Only steelhead now have access to the stream. Habitat restoration effortsupstream are of questionable effect because of the continuing aggradation and lack of apermanent solution to the present blockage.Eight lower Klamath tributaries were also analyzed for landslide frequency. Theresults (Figure 2-8) indicate a geometric increase in landslide frequency for all but two ofthe streams (Leopold 1981). Between 1940 and 1960, 77% of Little Pine Creek washarvested. Landslides in the watershed averaged 1 per sq. mile in 1950 but jumped to30 per sq. mile in 1965. While the 1964 flood obviously exacerbated the situation, thewatersheds were more vulnerable as a result of land management activities. Leopoldconcluded that "the effects not only accumulate with each increment of land surfacedisturbance, but each increment has a larger effect than the preceding one."Such a rapidly increasing rate of change indicates a threshold being exceeded.As a result, the naturally resilient watershed system is finally thrown out of equilibrium.Impacts of Timber Harvesting on Salmon and SteelheadOver the years, many studies have been made of the effects of logging practiceson water quality, streamflow, and aquatic habitat. It is not the intent here to provide anexhaustive review of the literature, but to highlight some of the latest findings, particularlythose from case studies in the Klamath Basin. In California, biological concern initiallyfocused on log jams blocking access by salmon and steelhead to spawning grounds.Later, interest expanded to streambed damage and to "erosion resulting from improperroad and skid trail construction on steep terrains" (Burns 1972). Local examples ofhabitat damage in the Klamath Basin are also described in Chapter 3 -- HabitatRestoration.Stream habitat impacts, potentially resulting from timber harvest activities, can begrouped into the following categories:o Riparian covero Water Qualityo Streamflow/runoffo Streambed qualityo Instream covero Stream channel stabilityo Migration barrierso Aquatic organisms