County Allocates $1.8M To Make Monte Rio Bridge Earthquake-Safe

SONOMA COUNTY, CA— The Sonoma County Board of Supervisors allocated $1.8 million Tuesday for engineering and environmental work in preparation for the seismic retrofit of the Bohemian Highway Bridge that spans the Russian River in Monte Rio.

The bridge, built in 1934, was identified by Caltrans as structurally vulnerable to failure during a major earthquake. The state called for the replacement of the entire bridge until the Caltrans Office of Earthquake Engineering reassessed the project and recommended focusing solely on seismic vulnerability.

"This bridge is a critical connection for West County, and I’m glad the seismic upgrade project is finally moving forward after eight years of planning and changes from the state," County Supervisor Lynda Hopkins said. "While we were hoping for a replacement, this project will extend the life of the bridge and address key safety concerns."

Multiple concerns with the bridge were identified by Caltrans in 2012, including potential seismic vulnerability, degrading foundations and inadequate bicycle and pedestrian access. An analysis at the time showed a replacement bridge would cost less than retrofitting the bridge's original span from 1934.

While discussions of the need for retrofit have occurred for roughly 20 years, replacement efforts began in 2015. Following community engagement by the county, state and federal grant funds were secured for the project. An Environmental Impact Report for the bridge replacement was finalized but project costs and designs changed and increased over the 10-year process, from approximately $25 million to $88 million —resulting in Caltrans re-evaluating the project.

The Bohemian Highway Bridge seismic upgrade project is eligible for reimbursement through the Federal Highway Bridge Program, with the county's matching portion funded by the state through the Local Bridge Seismic Retrofit Account.

The county invited 925 engineering firms to respond to the project announcement and received two proposals, choosing Fresno-based Cornerstone Structural Engineering Group, Inc. for the project.

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