Highway 37 keeps flooding

Highway 37 keeps flooding. For Novato, that's not just a commute problem, it's an evacuation crisis.

The morning of January 4, 2025, Highway 37 near Novato became a lake. The highway was flooded a year later. Again.

King tides, the highest of the year, pushed water 2.5 feet above normal levels, the worst flooding since 1998 (San Francisco Chronicle). By 5:30 p.m., both directions of the highway were closed near the Atherton Avenue interchange (NBC Bay Area), stranding thousands of commuters and cutting off one of the North Bay's most critical transportation arteries.

For Novato residents, this wasn't just an inconvenience. It was a preview of a worst case scenario: what happens when your main evacuation route is underwater?

The problem isn't new, but it's getting worse fast

Highway 37 has been sinking into the San Pablo Bay marshland for years. "When we get heavy storms and King Tides at the same time, we lose State Route 37. It floods," said Bart Ney, a Caltrans spokesperson. "That happened in 2017. It happened in 2019 for significant periods of time. It happened just last year for about a day, maybe two days." (CBS News)

But here's what makes this genuinely scary for residents: Highway 37 is the only major evacuation route from the North Bay if the San Rafael/Richmond Bridge should be unavailable (Sonoma Index-Tribune). And during the recent King Tides, Highway 101 flooded at the same time. Both major routes, simultaneously impassable.

The road sits at the intersection of two accelerating crises. About 40,000 people drive Highway 37 daily, many of them commuters priced out of living in Marin or Sonoma counties who've found affordable housing in Solano County. Meanwhile, Caltrans projects the stretch could be underwater by 2040 (Marin Independent Journal) — just 15 years away.

The "solution" everyone agrees won't actually work

California is spending half a billion dollars on a fix that officials admit is temporary. A $500 million widening project is planned to begin in late 2026 (Ksro), adding lanes and raising some sections by a few inches.

Representative Jared Huffman, who represents the area, didn't mince words: "It's going to be obsolete within 15 years of completion, and they're going to add insult to injury by tolling everyone to drive on it. It's really poorly conceived, unfortunately." (Marin Independent Journal)

Why build something that won't last? Politics, funding, and urgency. The traffic is bad now, afternoon commutes are delayed by more than 90 minutes (Marin Independent Journal) and officials feel pressure to do something, even if that something is a bandaid on a gunshot wound.

The real fix exists. It just costs $10 billion.

The State's long term plan is to build a four lane "causeway", essentially a low level bridge spanning most of the 21 miles from Vallejo to Novato, including bike lanes, pedestrian paths, and a rail line for the SMART commuter train (CBS News).

"Putting the alignment up on a causeway allows us to not only address the sea level rise, but actually have considerable improvements to the natural hydrology and natural functions to occur," said Jeff Berna, a consultant on the project study (The Press Democrat).

The causeway would solve multiple problems: it would be resilient to sea level rise, reduce traffic congestion, and allow for massive wetland restoration underneath — turning a climate vulnerability into an ecological asset.

There's just one problem: the causeway could cost more than $10 billion and isn't funded (The Press Democrat). Project officials envision "this taking 20 years to get this thing entirely built" (The Press Democrat), meaning completion around 2045.

That timeline got even murkier recently when the Trump administration blocked funding applications for climate infrastructure projects in Marin, including $13.5 million to prevent flooding at a Highway 101 exit and $18 million to strengthen a damaged levee (San Francisco Chronicle).

What does this mean for you?

If you live in Novato or anywhere that relies on Highway 37 for evacuation, here's the uncomfortable truth: don't count on it.

The nearest timeline relief is the Novato Creek Bridge replacement, which just received $25 million in funding and will be the first completed segment of the highway overhaul (Marin Independent Journal). But even that's years away from completion, and it's just one bridge.

For now, your options are:

During flooding: The official detour is Highway 101 to Interstate 580 (the Richmond San Rafael Bridge), then eastbound on Interstate 80. But if both 37 and sections of 101 flood simultaneously — as they did this January — you may have no good options.

For emergencies: Novato has evacuation zone maps through Zonehaven. Sign up for AlertMarin (text your ZIP code to 888777) to get real time emergency notifications. Know at least two ways out of your neighborhood, and don't assume Highway 37 will be one of them.

Long term: This is a political problem as much as an engineering one. Some funding may come from Proposition 4, a climate bond voters passed in 2024 that set aside $1.2 billion for Bay Area coastal resilience (San Francisco Chronicle), though Marin's share would be a small fraction of what's needed.

Contact your representatives, particularly those on the State Route 37 Policy Committee and in Congress, to advocate for accelerated funding of the causeway solution rather than continued investment in temporary fixes.

The bigger picture

Highway 37 is a microcosm of California's climate infrastructure crisis. We built critical systems assuming water levels would stay constant. They won't. We're now stuck choosing between expensive short term patches and even more expensive long term solutions we can't quite afford.

For Novato residents, the stakes are particularly acute. This isn't just about sitting in traffic. It's about whether you'll be able to get out when you need to.

The good news? Officials finally seem to agree on what needs to happen. The bad news? It might not happen fast enough.