The Skokomish Tribe is wrapping up a significant restoration of the Skokomish Estuary and will now watch how Mother Nature responds to the work.
The past decade has been filled with dirt-pushing, tide gate-removing, culvert-replacing, wood-installing, beach-seining, vegetation-measuring and channel-digging work, restoring 1,000 acres of farmland back into an estuary historically used by the tribe before the 1900s.
It started in 2007 with the removal of a mile-long dike parallel to Kwakwachalko (formerly known as Nalley Slough, named for the former property owner), to allow natural tidal flow into the estuary, recreating natural fish habitat adjacent to the Skokomish River.
The dike, built in the early 1940s, had prevented tidal flow, eliminating important juvenile salmon rearing habitat. The adjacent Skokomish River supports Hood Canal summer chum and Puget Sound chinook salmon, both listed as threatened under the federal Endangered Species Act.
The tribe installed a raised concrete boardwalk to allow tribal members easy access to the estuary and tidelands for harvesting traditional plants and shellfish. It also lets the tides and floods flow freely onto the floodplain.
In 2010, the tribe started work east of the boardwalk on Sweeplachub (formerly known as Nalley Island) by removing the dikes and culverts that made up the island, allowing historic channels to flow freely again.
In 2012, the tribe used aerial photos from 1938 to find more historic channels that were at the mouth of the river, and placed more than 250 rootwads and logs to help recreate those channels. By this point, about 350 acres and 20 miles of stream channel length had been restored.
The final phase of the work connected freshwater wetlands to the estuary, including construction of multiple bridges and installation of large culverts, plus recreating more historic channels.
“Opening the salt marsh and floodplain to the river and tide cycles is key to restoring the estuary and its habitat,” said Alex Gouley, the tribe’s habitat program manager.
The tribe’s natural resources departments have been monitoring the changes for the past decade. Fish biologists and technicians are counting out-migrating smolts using the newly recreated channels year-round. Within the first year, staff found 20 fish species, including chinook, chum and coho salmon, in areas where no fish had been seen before.
“We found the same fish species in the restored areas that were only previously found in areas that had not been diked or graded,” said Anthony Battista, a tribal fisheries technician.
In addition, the tribe is collecting data on sediment accumulation and salinity in the estuary’s soils.
“Since vegetation is a key indicator of restoration success, it is important to monitor the salinity and elevation of sediment so we can predict possible impacts, such as saltwater intrusion,” said Lisa Belleveau, the tribe’s habitat biologist.
Water quality in the river and tributaries has been observed closely, including sampling for bacteria and nutrient pollution, plus monitoring for temperature, salinity, pH and dissolved oxygen.
The shellfish staff has been monitoring how the tideland conditions have changed for shellfish habitat.
“It appears that the return of more natural hydrodynamics has resulted in scouring of some of the tidelands and deposition of larger grain sizes, leading to improved sediment for shellfish habitat,” said Chris Eardley, the tribe’s shellfish management biologist.
“The tribe will accelerate a return of the tidelands to conditions closer to what likely existed prior to the modifications that occurred more than 70 years ago, supporting important shellfish resources for the tribe.”
The tribe’s wildlife staff has been doing monthly bird surveys to determine changes over time in abundance and diversity. So far to date, the staff has identified 114 different species during their surveys.
And finally, as the estuary has been restored, the tribe has been using it as a living classroom. Annually, students from area schools visit the estuary for outdoor science programs, some of which include returning students who have grown up with the changing views.
Much of the hands-on work is finished.
“Now we’re in adaptive management mode,” Gouley said. “We’re monitoring how the estuary is taking to the work we’ve done and if we need to do any modifications. But we’ll never stop making sure it’s the healthiest it can be for the fish, shellfish and wildlife that use it, as well as for our tribal members.”