Upper Sandy River Basin Habitat Restoration Project

Sandy River salmon and steelhead populations have declined over the last century due to degradation of habitat and other factors. The Sandy River Basin Partners (the Partners) have identified the Salmon River and Upper Sandy 6th Field watersheds among the top four areas providing high quality habitat for the basins native fish. The Partners are aligned on a near term goal of restoring these priority watersheds to advance Sandy basin-scale restoration. Completed restoration actions on the Salmon River, its tributary Boulder Creek, and the Zigzag River address primary limiting factors for Sandy basin salmon and steelhead on public land managed by the USFS and BLM located near Welches, Oregon in Clackamas County. This includes the reactivation of flow to historic side channels and floodplain habitat, construction of large wood habitat structures and instream roughness elements, and placement of additional large wood in side channels and on stream margins at all three worksites. Proposed metrics that were originally reported for a single proxy site were distributed to the final worksites.

Sandy River basin spring Chinook, coho and winter steelhead are negatively impacted by loss of habitat. This project will restore habitat elements believed to be most limiting to these fish. The actions proposed will increase habitat complexity and diversity on the Salmon River, Zigzag River and Boulder Creek by increasing side channel habitat, off channel habitat, floodplain connectivity and large wood abundance.

Reactivation of flow to off-channel habitats is intended to provide spawning and rearing habitat for salmon and steelhead. The side channel design intent is to create a permeable, year-round connection point between the mainstem river and existing off-channel habitat. Alluvial material will be excavated from side channel entrances and large wood structures will be built at entrances and associated floodplains to moderate flow, provide scour to maintain the inlet, and provide complex fish habitat.

Large wood habitat structures and large wood placement are intended to maintain and improve side channel, alcove and floodplain connection, and restore habitat complexity and diversity by creating and enhancing scour pools, increasing hydraulic complexity and velocity refugia, promoting gravel deposition, and recruiting naturally occurring large wood. Large wood structures have been designed to emulate structures that existed prior to watershed alteration, and are designed to be self-sustaining.

Restoration objectives to address limiting factors were developed via restoration planning documents. Plans identify current conditions for limiting factors (eg. large wood abundance), historic conditions and restoration potential (the difference between current and historic conditions). This approach provides numeric targets that allow the Partners to develop project objectives that are directly tied to watershed objectives and Sandy basin-scale goals. In addition, monitoring of fish and habitat response makes it possible to adaptively manage the implementation of the restoration plan over time.

The Partners believe that focused, basin-scale restoration work, informed by basin-scale targets that address limiting factors, offers the best approach to ensure recovery of Sandy fish populations. To date, the Partners have completed planned actions in Still Creek, Lost Creek, Cast Creek, and lower South Fork Salmon River, while work in the Salmon, Salmon tributaries, upper Sandy sub-watershed, and mainstem Sandy corridor continues. The proposed project will implement analogous actions that TFT, USFS and BLM have used successfully to restore habitat elsewhere on the Salmon River, Still Creek and Lost Creek on behalf of the Partners. Effectiveness monitoring and observational data demonstrate that these actions have consistently achieved the desired habitat and fish response. Data shows that past work is restoring ecosystem processes so that high quality habitat is self-sustaining. Passive restoration continues in reaches where we have met applied restoration targets, providing a strong indicator of the Partners’ restoration approach and likelihood of proposed actions benefiting salmon and steelhead.

The Pacific Northwest is expected to see dramatic increases in temperatures due to climate change, with more rain in winter and spring, increased variability in peak flows, reduced snow-packs and drier summers. The Partners’ planning documents recommend actions that will recover natural river processes and riparian function by reactivating the floodplain and naturally aggrading the rivers; which will disperse flood flows providing high velocity refuge and attenuating downstream flooding, increasing hyporheic flows and decreasing water temperature, and providing cold water refuge and carbon sequestration in healthy native riparian stands that exclude invasive plants.