Buffers & Beavers Help Salmon at Pilchuck Tree Farm
/If you were a salmon traveling upstream, your chance of making it to your spawning bed hinges on many factors including the temperature and abundance of water. As a result, continuous streamside tree canopy and resident beavers are critical players in a salmon’s success. Trees shade and cool the water temperature, while beavers’ infrastructure supports consistent streamflow and helps create cool, deep pools.
“Trib 80” is an unnamed stream flowing into Pilchuck Creek in the Stillaguamish watershed. Although it’s unnamed, Trib 80 plays an important role in the health of Pilchuck Creek and the salmon that spawn there, which includes Chinook salmon and steelhead, both of which are listed as threatened under the Endangered Species Act.
Trib 80 is a cool water source for Pilchuck Creek, which is especially important in the summer when the water temperature is warmer and water levels are lower, both of which can impede salmon migration to spawning areas. Mature tree cover along Trib 80 can help keep Trib 80 and Pilchuck Creek cool as climate change impacts summer water temperatures into the future.
In an effort to provide this tree cover, Snohomish Conservation District worked with several private property owners between 2008 and 2020 to plant riparian buffers along Trib 80. Snohomish County also completed riparian planting projects along this tributary. In 2020, the District approached property owners along Trib 80 again with offers to plant more buffers on their land. Pilchuck Tree Farm enthusiastically accepted. The tree farm cannot harvest close to the water, leaving prime real estate for streamside trees 100-200 feet beside the tributary.
The District is currently implementing Phase 1 of this work, which will plant 15 acres of riparian forest with funding from Washington’s Departments of Ecology and Recreation and Conservation Office, as well as donations from Pilchuck Tree Farm itself. Subsequent phases will expand the riparian planting to 24 acres.
While visiting Pilchuck Tree Farm last year, our Habitat Restoration Team was excited to see evidence of beaver activity. Beavers add pools to rivers and streams, which slows water flow and mitigates flooding. Slowing water also allows it to percolate into the soil and replenish groundwater, which supports summer stream inflow.
In addition to the riparian plantings at Pilchuck Tree Farm, the District is installing 20 Beaver Dam Analogues, which are intended to mimic the form and function of beaver dams, and Post-Assisted Log Structures to help mimic natural wood accumulations in the stream system. The goal of these structures is to encourage beaver activity, reconnect the incised stream to its floodplain, and create pools and habitat diversity in the stream to further protect salmon habitat along this stretch of Trib 80.
Our work at Pilchuck Tree Farm complements other habitat restoration and stewardship projects around the Stillaguamish Watershed. We’re honored to work with the private property owners and land managers who re-tree their streams and contribute to this important effort, and we look forward to supporting salmon recovery in the future.
This project has been funded wholly or in-part by the United States Environmental Protection Agency under an assistance agreement to the Washington State Department of Ecology. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does the mention of trade names or commercial products endorsements or recommendations for use.
This project was also funded by RCO and with a donation from the Pilchuck Tree Farm.
