New Report: State of the Science on Restoring Western Headwater Mountain Streams
The removal of beavers and other land disturbances have led many creeks to cut deeper into their valleys and detach from their floodplains, dropping the water table and drying out the landscape.
As western mountain snowpacks diminish and wildfires race across parched landscapes, appreciation has grown for the moist mountain meadows and wetlands that hold water up high, feeding streams throughout the summer and providing fire-resistant refuges for wildlife. Before beavers and their dams were largely eliminated by the fur trade, these natural water storage features and refuges were common across western states’ mountain landscapes.
The removal of beavers and other land disturbances have led many creeks to cut deeper into their valleys and detach from their floodplains, dropping the water table and drying out the landscape. A growing field of stream restoration, known as low-tech process-based restoration (LTPBR), seeks to reverse these changes through methods that mimic beaver activity in hopes of enticing them to return.
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Projects across the west have demonstrated the benefits of LTPBR on the landscape. Projects have improved water quality, provided important habitat, trapped sediment, increased riparian vegetation and forage, and bolstered resilience against drought, fire, and floods. These benefits are achieved by installing low-tech, hand-built structures, creating “speedbumbs” that enable water from snowmelt and storms to spread across the riparian area, slowing peak flows and recharging groundwater. The rewetted soil “sponge” supports healthy riparian vegetation and reduces wildfire risks.
As LTPBR projects have proliferated across western states, both excitement about their benefits and questions about potential impacts have grown. A new report from American Rivers reviews the published science and case study information on LTPBR to better understand the full range of benefits these projects can provide, and provides scientific evidence to address potential concerns. The report finds ample evidence for LTPBR benefiting habitat and buffering the impacts of droughts, floods, and wildfires, but concludes that more research is needed to better understand the full suite of ecosystem service benefits. It also provides insights on how to address human and social factors related to LTPBR projects, such as mitigating beaver dam impacts to infrastructure.