The North American Beaver (Castor canadensis) used to span nearly the entirety of North America but was nearly extirpated from many river systems due to human encroachment and exploitation. With the removal of these ecosystem engineers, streams and rivers lost a level of complexity that was previously provided by the presence of beaver dams. One river that has been affected is the Klamath River, which flows through 257 miles of southern Oregon and northern California and is essential to many communities, including the Yurok Tribe (USFWS, 2013). The Yurok Tribal Fisheries Program (YTFP) began installing Beaver Dam Analogs (BDAs) in McGarvey Creek in 2018 as a way of mitigating stream damage caused by historic land use and the decline in Castor canadensis populations. Objectives included increasing stream habitat complexity for native salmonids, including threatened Coho Salmon (Oncorhynchus kisutch). BDAs influence stream geomorphology, and monitoring the characteristics of these influences will further help us understand their potential role in restoration. Our study compared stream channel morphology of nine cross-sections at three BDAs at McGarvey Creek BDA Site 1 between two time periods: immediately following installation of the BDAs (2018), and three years post-BDA installation (2021). An overbank flow analysis was also conducted to observe changes in floodplain connectivity through the comparison of shear stress, wetted perimeter, and velocity values pre-BDA construction (2017), immediately following BDA installation (2018), and post-BDA installation (2021). The BDAs at our study site increased floodplain connectivity to adjacent hydrologic units and the addition of BDAs added a level of stream complexity previously lost. This study has provided further understanding of how BDAs influence stream geomorphology and fisheries habitat over time in McGarvey Creek.
Environmental Science and Management