The Skokomish Tribe’s recent salmon habitat restoration project on a working farm shows how such work can benefit both fish and farms.
The tribe purchased more than 100 acres of the old Bourgault farm in the Skokomish River Valley in 2011. The farm regularly floods during significant rain events as the Skokomish River cuts through the property at river mile 5, regularly spilling over the riverbank and sending fish into flooded hayfields.
While the tribe couldn’t prevent flooding, work was done in 2020 to redirect the water with a 2,500-foot-long and 12-foot-wide overflow channel that was dug through the farm to alleviate the flooding.
Now when the fields flood, most of the water stays within the channel and fish are able to take refuge, then go back to the river as needed, said Lisa Belleveau, the tribe’s habitat biologist.
“The channel is taking in flow that would have spread out on the farm, stranding tons of fish,” Belleveau said. “There were fish in the field all the time after major floods and they just ended up as bird food.”
The other end of the channel feeds into a wetland complex, where dirt mounds and large woody debris help slow the water flow, adding floodplain roughness to the habitat, Belleveau said. The mounds are made of fill from the channel and held in place by woven cedar mats. Large woody debris structures were installed on the river-facing side of the mounds, and then native trees, such as spruce, fir and cedar, were planted on the mounds.
“The couple dozen floodplain roughness mounds with woody debris promote forest recovery and habitat diversity,” she said. “When the channel becomes activated at about 15 feet, 5 inches, it diverts the sheet flow into the wetland complex. Once the overflow channel fills, the flow hits those mounds and doesn’t scour the farmland as much as before, slowing down the water, then later funneling it back to the river.”
The channel is beginning to scour from overflow, which is expected and will naturally carve the channel deeper over time, carrying even more flow into the wetland complex rather than across the field, she said.
The primary goal of the project is to restore salmon habitat and create a functional floodplain while minimizing disturbance to the land that is still used for farming hay, Belleveau said.
To further support the salmon habitat, the tribe established a riparian buffer of 75 feet on each side of the overflow channel that has been planted with nearly 8,000 native shrubs and trees. Plants include willows, cottonwoods, cedars, red osier dogwood and salmonberry, and seem to be establishing well, she said.
Establishing riparian buffers on salmon-bearing streams provides bank stability, shade, pollution control and the woody debris that salmon need to survive, she said, as it’s part of the overall salmon habitat restoration work needed to support salmon populations.
Alex Papiez, Skokomish Tribe restoration biologist, plants native vegetation behind one of the mounds that is supported by a logjam on Bourgault Farm. Story and photo: Tiffany Royal
