West Marin Drainage Rehabilitation



A culvert assessment was conducted to assess potential structural deficiencies of approximately 150 culverts along 14-miles of roadways in unincorporated areas of West Marin: Point Reyes Petaluma Road from Highway 1 to Platform Bridge Road, Lucas Valley Road from Nicasio Valley Road to Big Rock, and Nicasio Valley Road from Lucas Valley Road to Sir Francis Drake Blvd.

The culvert assessment report identified 29 road culverts requiring improvement due to dilapidated conditions that could lead to issue relating to flooding risk, public safety, and environmental regulations.  In addition, this project will address 2 roadside bank slip outs.


The estimated cost of the project is $3 million.

Traffic Impacts

There will likely be traffic impacts during construction with delays, which are expected to be less than ten minutes at a time.



  • Environmental permitting

Summer 2025

  • Anticipated start of construction
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