A $500 million project along Highway 37 has been modified to include swamp restoration work.

The Sears Point to Mare Island Improvement Project will widen the Tolay Creek Bridge and add a carpool lane in each direction to reduce traffic congestion. New updates include restoring a 3.5-mile section of degraded tidal salt marsh called Strip Marsh East, designed to help protect against sea level rise and flooding while creating habitat.

“Building a network of new canals connecting to San Pablo Bay will support the creation of new wetlands, water bodies and habitats for threatened and endangered species,” said Bart Ney, a spokesman for Caltrans.

Caltrans released a draft supplemental environmental report for the project in December — about a year after completing the environmental impact report for the project. The 2023 report found that the project had no significant environmental impact. The supplementary report comes to the same conclusion that most project elements have little or no impact.

Ney said the supplementary report aims to examine and disclose the potential impact of the changes. He said the project would improve drainage from the wetland to San Pablo Bay by lowering berms and creating canals. The new elements will counteract seasonal flooding that creates extremely salty conditions in the marshland, which has caused land subsidence and the death of seasonal vegetation.

The area is notorious for its traffic, with thousands of commuters from Sonoma County traveling to work in Marin and Napa every day. The project focuses on a 10-mile stretch of road that will be narrowed from two to one in each direction between Highway 37 and State Route 121.

According to James Cameron, executive director of the Sonoma County Transportation Authority, which is a partner in the project, afternoon commutes will be delayed by more than 90 minutes and morning commutes will be delayed by 50 minutes. Cameron noted that these delay averages are for the project only.

“Lane merges on SR 37 are the leading cause of congestion in this portion of the corridor,” the report states. “Within the project limits, faster vehicles cannot overtake slower vehicles as there is only one lane in each direction and overtaking is not permitted.”

Cameron said the project is expected to result in a travel time of 20 minutes in either direction to cover 20 miles of the corridor. He said the carpool lane would avoid tolls, while the general traffic lane would have to pay a toll.

The environmental assessment approved in 2023 approved widening the Tolay Creek Bridge, but the project would now replace the 60-foot-long bridge with a structure approximately 375 feet long and 90 feet wide.

The project is not without controversy. The report expressed public concerns about the long-term resilience of Highway 37 due to sea level rise, which Caltrans said could be underwater by 2040. Marin County Supervisor Eric Lucan, who represents Novato, said the route needs to be elevated.

“What I think is really missing is a rethink on the Tolay Creek bridge,” Lucan said. “It’s great that they’re planning to extend the bridge and it’s environmentally friendly now, but I still wonder why we’re even thinking about building a brand new bridge over Tolay Creek if they’re going to be under water in 15 years becomes.”

The project is estimated to cost around $500 million and will be funded through a mix of federal and state funds, as well as some grants and future toll revenue. Cameron said planners have about $100 million available so far.

Lucan wondered if the project could be done in stages to save costs, starting with raising Tolay Bridge Creek. Still, the changes, small as they are, are still worth noting, he said.

“There is tremendous opportunity for the restoration of this area and that is really exciting and something we should celebrate, but there is more that could be done,” Lucan said. “How do we find a project that addresses environmental restoration and the bottleneck, the congestion, that is really designed for long-term sustainability and sea level rise?”

“I think we’re getting closer, but we’re not there yet,” he said.

Cameron said the project would be phased in to address short-term issues such as traffic congestion while working toward the longer-term goal of elevating the road.

“It’s not a throwaway job, it’s the first phase of the long-term project,” Cameron said.

Ney said construction is expected to begin in the spring and be completed in the summer of 2029.

Caltrans plans a public hearing on the supplemental environmental report on Jan. 14 at the John F. Kennedy Library in Vallejo and online. Details about the meetings and instructions for accessing the conference call can be found online at shorturl.at/ZtHaL.

Originally published: January 6, 2025 at 2:25 pm PST