State provides $50 million for Highway 37, restoration of San Pablo Bay marshes

The California Transportation Commission approved a $50 million grant Dec. 7 to replace and lengthen Tolay Creek Bridge on Highway 37 that will promote restoration of the San Pablo Baylands.

The project will widen the bridge to two lanes in each direction, easing the bottleneck that often affects drivers on the thoroughfare connecting North Bay counties. The bridge replacement will also allow more water to flow in and out of Tolay Creek to alleviate concerns of sea-level rise that threatens San Pablo Bay marshes, according to the Bay Area transportation planning agency Metropolitan Transportation Commission.

“Together, these improvements will comprise the first phase of an estimated $430 million project to improve traffic flow along the 10-mile stretch of Highway 37 between Sears Point and Mare Island… reduce flooding along the corridor, as well as restore North Bay marshlands,” MTC wrote in an announcement Dec. 7.

While the project’s priority is to ease traffic congestion and protect Highway 37 from the expected 7 feet of sea level rise by 2100, there are benefits to the surrounding environment.

The replacement and lengthening of the Tolay Creek Bridge will widen the creek channel and reduce the vulnerability of flooding on Highway 37, according to Sonoma County Transportation Commission.

The marshes in San Pablo Bay are vulnerable to ecological change from rising sea levels and human activity, like water diversions for agricultural uses, according to the U.S. Fish and Wildlife Service.

“About 85 percent of the historic tidal marshes of San Pablo Bay have been altered, negatively affecting the ability of the remaining tidal marshes to accept winter rainfall and purify water in the bay,” the U.S. Fish and Wildlife Service said.

These changes threaten the thousands of species who forage, breed and nest in the baylands, including over 1 million birds that use it as a stop during seasonal migration on the “Pacific Flyway.”

“In the short term (upcoming decades) this will likely provide net environmental benefits vis-à-vis wetland enhancement/restoration,” said Steven Lee, senior scientist and research program manager. “But, big picture, this is a transportation planning project, not a wetland improvement project.”

The $50 million grant comes from the California Transportation Commission’s Local Transportation Climate Adaptation Program. The program was established in 2022 to support resilient infrastructure against the hazards created by climate change.

The funding will be shared between MTC, Caltrans and Sonoma County Transportation Authority among other project partners in Marin, Napa and Solano counties as part of the Resilient State Route 37 Program.

Contact Chase Hunter at chase.hunter@sonomanews.com and follow @Chase_HunterB on Twitter.