Mid-Willamette Beaver Partnership: Habitat Assessment and Prioritization

The 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 support through paired Technical Assistance actions. This project provided the opportunity to create a fine-scale beaver habitat assessment and prioritization tool which identifies key locations for enhancement through Beaver-based Restoration. Data from the Beaver Restoration Assessment Tool (BRAT) was combined with information gathered from regional experts to develop a regional beaver restoration action plan (BRAP) which includes restoration and conservation strategies for at least two reaches for each watershed council. The project effort also included the sharing of our results and process with partners, stakeholders and other restoration practitioners to advance beaver-focused restoration efforts across Oregon. This project has elevated the understanding of how individual projects within each watershed can have regional effects and has provided modeling for areas that are best avoided. Restoring beaver populations and habitats where appropriate, implementing mitigation strategies where conflict occurs, and mimicking dam-building activities can help rectify the losses of watershed ecosystem diversity and address legacy impacts while providing a cascade of ecosystem benefits to prepare against future disturbance.
Because the project’s actual end date falls outside of the PCSRF FFY 2020 award, no state funds on this project are reported 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.