Submitted by North Olympic Salmon Coalition
The swath of land between Indian and Marrowstone Islands was historically comprised of tidal channels and salt marsh. Tidal waters exchanged freely between Oak Bay and Kilisut Harbor, flushing cold water, moving sediment, and allowing juvenile salmon to migrate northward from Oak Bay into the shallow, productive waters of Kilisut Harbor.
The State Route 116 Causeway that bisects Kilisut Harbor and Oak Bay. Photo by Tom Roorda.
The two inadequately sized culverts under the causeway. Photo credit: ESRP and Scott Haydon Photography.
The installation of an earthen causeway between the islands in 1958 eased transportation, but choked the flow of water and sediment. Eventually this created an artificial beach berm, which filled the tidal channel, blocking fish passage and raising water temperatures at the head of Kilisut Harbor, also known as Scow Bay.
After many years of anticipation the project is set to break ground in August! The goal of the Kilisut Harbor Restoration Project is to restore ecosystem processes by restoring the historic tidal connection between southern Kilisut Harbor and Oak Bay by removing the earthen causeway and replacing it with a 440′ bridge.
Monitoring tidal elevations in the remnant tidal channel. Photo from NOSC archives.
State Route 116 connecting Indian and Marrowstone Islands. Photo credit: ESRP and Scott Haydon Photography.
These actions will restore tidal exchange and sediment processes to 27 acres of marine intertidal wetlands and tidal fringe salt marsh. The project benefits many species including salmon, shorebirds, waterfowl, shellfish and eelgrass, while also providing safer transport between the two islands.
The shallow tidal channel will be accessible to human powered craft and small powerboats at high tide. Also, this channel will connect two Washington water trail sites at each end of Marrowstone.
NOSC has led the charge to get the project funding portfolio finished, complete the project design, and acquire allnecessary environmental permits. The project construction will be managed by Washington Department of Transportation with assistance from NOSC on the tidal channel restoration.
Learn more about the project at www.nosc.org
For construction-specific information visit the WSDOT website.
Kilisut Harbor. Photo credit: ESRP and Scott Haydon Photography.