Our Projects

The goal is to restore fish passage and habitat connectivity by removing a failed fishway and barrier bridge.

The Napa County Resource Conservation District (Napa RCD) engaged WRA to develop 100% design plans and cost estimates for this fish passage barrier remediation project on Sulphur Creek, a major tributary to the Napa River in St. Helena, California. By removing a failed steel fishway and replacing a bridge that blocks migration, the project will reopen 3.2 miles of high-quality fish habitat upstream, supporting recovery of steelhead trout and Chinook salmon, California roach, and  Pacific lamprey while protecting nearby infrastructure and properties.

The project includes the removal of an existing dysfunctional steel fishway, along with the replacement of an existing bridge that creates a fish passage barrier. The fish ladder was installed in 2002 to improve fish passage prospects through the existing bridge and was deemed ineffective almost immediately due to scouring effects from the constrained flow.

WRA developed a resilient design approach that enhances habitat and protects adjacent infrastructure and properties.

WRA refined the existing 30% design (originally developed by a prior consultant) through a detailed hydrologic assessment of fish passage flows and hydraulic modeling to evaluate potential velocity and shear stress conditions. Historic downcutting of the creek at the project site has created a significant elevation drop below the bridge. To address this, the design reestablishes a natural channel through the reach while incorporating velocity refugia to support migrating fish. The design also stabilizes channel banks adjacent to the public road and residential properties while ensuring that flood risk to nearby parcels is not increased.

In parallel with the restoration design, WRA biologists conducted comprehensive rare plant surveys, carefully assessing features and microhabitats most likely to support sensitive species. Additional biological evaluations were paired with cultural resources investigations by our subconsultants, along with replacement bridge design. At the request of Napa RCD, WRA also managed all regulatory permitting and environmental compliance efforts. Our permitting strategy facilitated more streamlined approvals from key regulatory agencies, resulting in the successful completion of all State and federal authorizations.

Throughout the project, WRA collaborated closely with Napa RCD and funding partners, including the California Department of Fish and Wildlife’s Fisheries Restoration Grant Program and the California Coastal Conservancy’s Proposition 1 Grant Program.

The project will reopen 3.2 miles of high-quality habitat for steelhead and improved resilience of the creek system.

When construction is complete, Sulphur Creek will once again provide access to 3.2 miles of high-quality upstream habitat. The project eliminates a long-standing barrier, supports recovery of native fish populations, and enhances the long-term ecological resilience of the creek system and surrounding community.