Years of work to restore salmon habitat on a productive tributary to the Skagit River is expected to be completed this summer.
Most of Illabot Creek has been protected from habitat loss, but about a half-mile was degraded in the 1970s by construction of the Rockport-Cascade Road bridge. The channel was relocated and constrained. A steeper gradient reduced habitat complexity and limited connectivity with the floodplain.
“This work changed Illabot Creek from a sinuous, multi-thread channel throughout this reach to a straightened, single-thread channel,” said Devin Smith, restoration ecologist for the Skagit River System Cooperative (SRSC), the natural resources extension of the Swinomish and Sauk-Suiattle tribes.
The first phase of the Illabot restoration in 2013 removed 1,150 linear feet of dike, installed logjams and built pilot channels downstream from the road.
“If we don’t maintain the momentum of restoration activities, the restored habitat upstream of the Rockport-Cascade bridge will continue to be degraded by the bank armoring, and Illabot will be isolated from 10 acres of floodplain,” Smith said.
Between now and August, an additional 850 linear feet of dike will be removed, two new 100-foot bridges will be built, and logjams will be installed to reconnect the creek with historical channels.
“The existing bridge will be left in place,” Smith said. “When the project is completed, any one of the three bridges could convey all or a portion of the flow from Illabot Creek.”
Eventually, natural processes of erosion, deposition and channel development will take over, increasing spawning and rearing habitat for chinook, chum, coho and pink salmon, steelhead trout and native char.
“We expect the habitat restored by this project to be colonized quickly and used by multiple species,” Smith said.