Project overview
Between summer 2020 through summer 2022, contractor crews working for the Washington State Department of Transportation worked to remove and replace two existing culverts that lead to the Chehalis River located underneath SR 6 near Twin Oaks Road (between mileposts: 46.32 to 46.59) in Lewis County.
What to expect
Final construction on this project ended in summer 2022.
Between summer 2020 through summer 2022, contractor crews working for the Washington State Department of Transportation worked to remove and replace two existing culvers that lead to the Chehalis River located underneath SR 6, near Twin Oaks Road, (between mileposts: 46.32 to 46.59) in Lewis County.
Needs & benefits
Constructed in 1971, these two culverts were in need of replacement in order to meet a federal court injunction issued in March 2013. This injunction requires the state to increase the effort for removing state-owned culverts that block habitats for salmon and steelhead by 2030. Replacing these two fish barriers was part of this effort.
How culverts became barriers
Most of the culverts located underneath roads and highways were installed decades before scientists fully understood the needs of fish. At the time of construction, WSDOT met all requirements for culvert installation and sizing, and a culvert that was fish passable at the time of installation might have become a barrier over time due to changes in the landscape and stream flows resulting from development, logging, and fire. The new fish-friendly structures we construct now are larger, more resilient to changes in the landscape, and provide fish passage long into the future.
WSDOT has worked for nearly three decades to improve fish passage and reconnect streams to help keep our waterways healthy by ensuring fish habitats are free from barriers and obstructions.
The end result
A single barrier removal can deliver impressive benefits, improving fish access for hundreds of miles both upstream and downstream. Once construction on this project is complete, the new fish-friendly structure will improve access to about 1,215 miles of potential habitats for many years to come. This is an important component of protecting and restoring fish populations which can in turn have multiple benefits, including those for commercial and recreational fishing industries.
- Protects environment: Improving fish passage by opening up the stream creates additional fish habitats.
- Improves safety: Replacing the culverts with a concrete bridge span lessens erosion around and underneath roads by providing better drainage.
- Reduce costly repairs: Replacing the culverts with a concrete bridge span will reduce the cost of emergency maintenance repairs and closures
