The $95 million that North Bay leaders spent Wednesday demanding from the state would launch the long-promised rebuild of Highway 37 — a project California could only greenlight after the Legislature agreed last year to let a rare marsh mouse and three protected birds be killed to speed construction.

On Friday, the California Transportation Commission meets in San Diego to vote on releasing the money for the tide-swamped corridor linking Marin, Sonoma, Napa and Solano counties. The press-conference framing is a simple one — release the funds, ease a punishing commute. But the vote sits atop a tradeoff that got far less attention at the Sonoma event on Wednesday: the fix advances only because Gov. Gavin Newsom signed a 2025 bill loosening the state's own wildlife protections, and some of the environmental groups that once fought that bill are still fighting the wider highway it enables.

Labor and elected leaders from across the Bay Area gathered Wednesday at a ranch beside the highway in Sonoma County to press the state to bankroll the modernization of the 21-mile route, which KQED reports (external source, opens in a new tab) now carries more than 40,000 vehicles a day and backs up past 90 minutes along a single-lane, low-lying segment between Vallejo and Novato. Marin County Supervisor Stephanie Moulton-Peters, who sits on the corridor's regional policy committee, urged commissioners to fund the work now rather than relitigate the need year after year. Rep. Mike Thompson, who has steered federal dollars toward the road, pointed to the years crews spent dividing traffic with temporary K-rail barriers because a permanent fix kept getting deferred.

What the podium speeches largely left out is how the money in front of the commission this week became spendable at all. The Friday vote covers two separate budget items totaling about $95 million — $32.35 million to rebuild the Sears Point intersection where Highway 37 meets Highway 121, and $62.79 million toward the opening phase of the broader corridor overhaul between Sears Point and Mare Island, which swaps the Tolay Creek Bridge for a longer, higher span. (Several outlets, including the San Francisco Chronicle (external source, opens in a new tab), round the ask to $100 million once related federal dollars are counted.) The agency intends to put the combined contract out to bid in September, with groundbreaking targeted for May.

The corridor's problem is not only traffic. The roadbed sits barely above the tideline as it threads the San Pablo Baylands, and Caltrans says the rebuild is engineered against sea-level rise projected through 2050 — a tacit admission that the highway is slowly drowning.

Spending money on expanding a highway that already floods regularly is a waste of taxpayer money," Deutsch-Gross told KQED.

But building across a protected marsh meant colliding with California's own wildlife law. Last October, Newsom signed Assembly Bill 697 (external source, opens in a new tab), authored by Solano Assemblymember Lori Wilson, which lets state regulators authorize a capped number of deaths of the salt-marsh harvest mouse, the California Ridgway's rail, the California black rail and the white-tailed kite — so long as Caltrans restores habitat in exchange. When the Legislature took up that waiver in 2025, CalMatters reported (external source, opens in a new tab) that the old rules confined crews to only about 10 to 12 weeks of work each year. Supporters call that the line between a buildable project and a permanent standstill.

Not everyone signed off on the bargain. In a 2024 letter to Senate leadership, two dozen organizations warned the carve-out would tempt other highway-widening projects to seek the same exemption. The lead signatory, the nonprofit TransForm, is not opposing Friday's item — its policy director, Zack Deutsch-Gross, told KQED the group is neutral on the bridge replacement while it keeps fighting the extra lanes planned for later phases.

"Spending money on expanding a highway that already floods regularly is a waste of taxpayer money," Deutsch-Gross told KQED.

Backers lean hard on equity. Joshua Arce of the California Alliance for Jobs told KQED that a lopsided 85 percent of the highway's commuters earn beneath the regional median wage — more than double the share on other Bay Area roads — and that the build could generate up to 5,000 Solano County jobs, in a county that carries the region's worst unemployment rate.

The path to Friday has been long and costly. KQED notes the Sears Point work was first programmed in 2022, lapsed in 2025, and had to be reprogrammed; a July estimate drove costs 54 percent higher after engineers hit bay mud that forced a switch to pile-supported retaining walls. Dan Reding, a union official for the Caltrans crews who maintain the road, told KQED the overhaul has been debated for more than three decades and is overdue for action.