Mid-Willamette Beaver Partnership: Habitat Assessment and Prioritization

Overwhelming support exists among researchers, agencies, and restoration/conservation organizations to develop a social-ecological road map for promoting beaver and their dams. In response, Bonneville Environmental Foundation (BEF) and the Luckiamute (LWC), Marys River (MWRC), and North Santiam Watershed Councils (NSWC) have formed the Mid-Willamette Beaver Partnership (MWBP) to leverage that support through this proposal. These basins, covering parts of Marion, Linn, Benton, Lincoln, and Polk counties, are host to ESA-listed Chinook and winter steelhead and a wide array of beaver-dependent fish and wildlife species. Based on existing data analysis, this project proposes the development of beaver management plans and restoration and conservation strategies for at least two reaches for each watershed council.

Because the projects end date falls outside of the PCSRF FFY 2020 award period, no state funds are used as match to PCSRF.

Major limiting factors to improving salmonid production in general, and specifically in the mid-Willamette tributary basins, include warm summer temperatures, a lack of in-stream habitat complexity, and a lack of gravel substrate retainment for spawning. Incised single-threaded channels lead to high velocity flows, high sediment export, poor groundwater recharge or hyporheic flow, and a reduction of pool-riffle morphology. Climate change exacerbates these conditions with higher frequency of drought and flashier streams during the rainy season. Salmonid habitat suffers as a result with minimal areas to be utilized for cover from predators or high velocity flow, reduced food production and little opportunity for spawning. Beaver dams alter these processes and improve salmonid habitat by retaining sediment that begins rebuilding incised channel streambeds, reconnecting floodplains, recharging groundwater and improving summer baseflows. Spatially and quantitatively, beaver dams create more fish habitat. A common misconception is that beaver ponds increase stream temperatures when in fact, the temperature stratification and the improved ground-surface water connections that occur in ponds are more likely to improve temperature conditions downstream during low summer flows (Weber et al. 2017). Declines in salmonids have been attributed to declines in beaver habitat and the positive correlations of beaver complexes with salmonids and other native fish are extensively documented (Burchsted et al. 2010; Castro et al. 2015; Bouwes et al. 2018; Dittbrenner 2018). The habitat scoping and restoration plan proposed in this application will allow the Luckiamute, Marys River and North Santiam Watershed Councils to identify and prioritize reaches to target for beaver-based restoration and conservation strategies. Prioritized reaches can also serve as translocation sites for beaver trapped on properties where coexistence is not possible. These follow-up restoration and conservation activities will increase aquatic habitat quantity and improve habitat quality for salmon and steelhead, along with many other aquatic organisms.