Management history of eastside ecosystems: changes in fish habitat over 50 years， 1935-1992. Part 2.

From 1934 to 1942， the Bureau of Fisheries surveyed over 8000 km of streams in the Columbia River basin to determine the condition of fish habitat. To evaluate changes in stream habitat over time， a portion of the historically surveyed streams in the Grande Ronde， Methow， Wenatchee， and Yakima River basins were resurveyed from 1990 to 1992. Streams were chosen where the primary impacts were natural disturbance (unmanaged)， such as wilderness and roadless areas， and where human impacts (managed) were the major disturbances. In addition， historical changes in land-use， stream flow， and climate regimes were also analyzed. Many of these streams had been degraded from land-use activities (riparian timber harvest， splash dams， stream channelization， livestock grazing， and mining) prior to the historical survey. While the general trend throughout the Columbia River basin has been towards a loss in fish habitat on managed lands and stable or improving conditions on unmanaged lands， the data for these four river basins suggest there is a regional pattern to this change. Based on this information， along with data on the status of anadromous fish runs in these basins， fish habitat has shown some improvement from past abuses in eastern Washington， while continuing to decline in eastern Oregon. This appears to be the result of different land-use histories in the two regions. The river basins of eastern Washington apparently had a period of recovery after World War I from past land-use practices， as the impacts of development decreased. In contrast， river basins of eastern Oregon have been affected continuously by land-use practices over the entire development period (1850-present). From this information， it is clear that land-use practices have degraded fish habitat throughout eastern Washington and Oregon. Strategies to protect， restore， and maintain anadromous and resident fish populations and their habitat， must be based on a watershed approach that protects the remaining habitat and restores historical habitats. (From Volume III: Assessment/Paul F. Hessburg， Science Team Leader and Technical Editor; Eastside Forest Ecosystem Health Assessment/Richard L. Everett， Assessment Team Leader)