Site conditions for the S. Fork Newaukum R. RM !0.9-13Early Action Project Reach reflect a complex geologic and glacial history as manipulated by a legacy of logging, channelization, and landcover conversion. Prior to human disturbance the project reach likely consisted of extensive floodplain wetlands and forests, numerous large wood accumulations, and narrower, multi-thread or anabranched channels. The first European settlers arrived circa mid-19th century and began the homesteading and clearcutting practices that resulted in channelization and the losses of riparian vegetation, wetlands, and forests.

This legacy of landcover conversion and channel manipulation combined with regionally significant flood events triggered bank stabilization projects that exist throughout the reach, limiting lateral migration, and progression through the stages of channel evolution described in other chapters. Two-dimensional hydraulic simulations show that there is very little connection of floodplain habitat features during average seasonal events, with small backwater channels and alcoves becoming activated at near the annual flood of approximately 850 cfs. As flows increase, floodplain channels become activated, and substantially more floodplain becomes inundated around 3,800 cfs, which corresponds to the 2-year event. Widespread inundation begins to occur at flows between the 5- and 10-year events. Preliminary analysis suggests that habitat availability in the transition between the average seasonal events to regular flood event flows is where the most profound impacts to available fish habitat occurs.

Large wood dynamics reflect a legacy of river and forest management with recruitment primarily from upstream reaches through slope failure and avulsion processes. Certain sections of the study reach do recruit large wood via bank erosion processes, but the wood represents second or third growth timber that is smaller than historical wood sizes and does not have the same ability to self-stabilize within the channel.

The South Fork Newaukum River supports anadromous runs of winter steelhead, fall Chinook salmon, spring Chinook salmon, and Coho Salmon. Physical habitat modeling suggests that the primary controls on habitat suitability are the result of the low baseflows and high velocities associated with the simplified channel and floodplain typical of the study reach. While certain subreaches of the study reach exhibit physical properties associated with higher functioning streams (e.g., frequently connected floodplains, mobile beds on an approximately a