The SR 108/US 101 Mason and Thurston County Fish Barrier Removal project was recognized with a 2025 Project of the Year Award (Environment $25 Million to $75 Million) from APWA Washington at the chapter’s annual awards banquet on April 24. GeoEngineers is proud to have provided geotechnical engineering, stream design, and environmental compliance and permitting services for this important Washington Department of Transportation (WSDOT) project as a member of a Stantec/Walsh design-build team. Joe Callaghan, David Conlin, Cora Johnson, Sean Cool, Mark Rose, and Dan Eggers were on hand at the awards banquet last Thursday to celebrate with the design-build team. Congratulations to everyone who contributed to making this award-winning project a success!
The SR 108/US 101 Mason and Thurston County Fish Barrier Removal Design-Build addressed five fish barriers at stream crossings along SR 108 between McCleary and Kamilche, Washington, and one crossing (two culverts) on US 101 near the Mason/Thurston County line. Like many other culverts under Washington State roadways, they were preventing salmon from accessing miles of upstream spawning and rearing habitat. Fish barrier replacement requires coordination from environmental permitting specialists, geotechnical engineers, hydrologic/hydraulic professionals, and habitat and fluvial geomorphic stream experts.
The outdated crossings included small-diameter culverts—and one even had a fish ladder. Larger structures (mostly precast concrete box culverts or three-sided culverts) were installed that improve hydraulic performance and support natural stream channel and habitat-forming conditions. One crossing design used a buried structure supported on drilled shafts to compensate for the soft and liquefiable soils present. Each of the designs included wingwalls consisting of either pre-cast concrete or mechanically stabilized earth (MSE) walls to manage roadway stability and transitions.
As is typical for GeoEngineers’ stream projects, our team created site-specific plans to protect aquatic life before installing stream bypasses, all completed during a short in-water work window when sensitive species were least likely present. They even took additional steps to protect several unexpected species that turned up in the project area—freshwater mussels and Olympic mudminnows! In total, the project restored more than 2,000 feet of self-sustaining stream habitat, incorporating natural features like engineered wood placements and native plants to support long-term ecological health.
Last year, Megan Hernandez Stites captured video of salmon already making good use of the restored habitat near one of the crossings. Check it out below or on GeoEngineers’ YouTube page!
“There were so many chum salmon spawning upstream and downstream of the structure,” Megan said, “It’s amazing to see the results of our work!”
