How crews are prepping flood-prone Highway 37 for rain

Ahead of winter rains, state transportation crews are wrapping up paving and drainage improvement work along Highway 37 in an attempt to avert flooding, which in two of the past three years led to multiday closures of the critical North Bay commuter artery.

The roadwork, the bulk of which was completed last month, is part of a larger prevention plan that Caltrans launched this fall to ensure the state highway that links Novato to Vallejo via Marin, Sonoma, Napa and Solano counties remains open during the wet weather.

The plan also includes setting up materials near trouble spots in Sonoma and Marin counties to establish an emergency floodwall that can be deployed quickly, if needed. The floodwall could prevent the highway from being overtaken by water, or at least minimize the length of time it’s knocked out of commission.

“Flooding on the Highway 37 corridor is not acceptable, which is why Caltrans mobilized and organized to get the job done prior to rainy season hitting,” said state Sen. Mike McGuire, D-Healdsburg. “Hope is not a strategy for success, and why we used emergency funding to make these fixes on the most vulnerable stretches.”

The aggressive approach was developed out of monthly meetings between McGuire, Caltrans and officials in the four counties. They decided that adding up to a foot of asphalt on the road’s low-lying areas between Highway 101 and Sears Point would help avoid more shutdowns this winter, when flooding is most likely due to heavy rains joining rising tides out of the adjacent San Pablo Bay.

In February, CHP twice closed the problematic section near Novato Creek to the roughly 45,000 motorists who drive the highway each weekday because significant storms overwhelmed and breached area levees. The first incident closed the highway for five days before road crews were able to get it drained and drivable. Less than a week later, the highway closed, again, for three more days.

Those incidents followed a similar set of closures in 2017, when record rainfalls forced full or partial shutdowns of that segment of Highway 37 for a total of 27 days. Emergency repair work that year cost $10 million.

The round-the-clock work earlier this year, combined with the recent paving and drainage enhancements, has cost about $6.7 million, according to Caltrans. The state transportation agency also paid $20,000 for a second tractor-based water pump to divert floodwaters elsewhere if and when the time comes.

“I think this time we’re actually in a much better position than we were last year,” Caltrans District Director Tony Tavares said at a Highway 37 town hall held earlier this fall. “We have a lot of the materials needed to put additional floodwalls and barriers in place as quickly as possible. That’s going to be very important this year.”

With a plan in place for the near term, officials have also kept their attention on a permanent fix for what they call one of the most important and challenging transportation corridors in the region. Even if this year’s contingencies hold, the 21-mile roadway remains susceptible each year to sea-level rise from the growing effects of climate change.

“Prepositioning things is just a wise move and helps, until one of those major storms lay waste to everything,” Sonoma County Supervisor David Rabbitt said of the new precautionary measures. “It is significantly better. But is it still vulnerable? Obviously, yeah.”

As a result, McGuire helped secure $10 million in state transportation dollars for the first phase of environmental and engineering studies needed for a longer-term solution for the highway. Another $100 million was dedicated to the overarching project through Bay Area bridge toll hikes approved by voters in June 2018, but the money remains tied up in a legal battle, and no one knows how or when it will be resolved. Highway 37 advocates are optimistic the California Transportation Commission will soon commit more money to further study elevating the highway 15 feet off the ground.

If that happens early next year, Tavares said the project’s environmental work could be finished by 2023. After another year of design work, construction on what has been estimated a $3 billion causeway could start as soon as 2025 - a fast turnaround for such a large-scale infrastructure project, he said.

However, finding the money to build it will be the next major hurdle.

Those discussions have already begun at the Bay Area’s Metropolitan Transportation Commission.

The transit agency’s legislative arm is considering lobbying next year for a bill to approve the region’s eighth state-owned toll bridge, which would require the governor’s signature to move forward.

“I am definitely open to the concept and, candidly, don’t believe there is another option out there,” McGuire said. “This is a priority for the entire North Bay legislative delegation and, look, let’s be honest, the tens of thousands of commuters who have suffered long enough. It’s time for a longer-term fix.”