Marin County Looked Like ‘a Lagoon’ After King Tides, Heavy Rain

A 3-foot-tall line of grey sandbags and blue tarps surrounded the entrance of Fitness SF in Corte Madera on Monday morning. This makeshift wall and a temporary pump stopped water from a nearby lagoon from turning the gym into a swamp.

“We would have easily been 2 feet underwater,” said Ryan Davis, the gym’s general manager.

The intensity of this weekend’s storm, coupled with a king tide, caught Marin County cities like Corte Madera, Sausalito and San Rafael off guard. Floodwaters spilled over levees, covered bike trails, and surrounded homes and businesses.

County officials told KQED on Monday the exact damage estimates aren’t yet known, but that hundreds of structures were impacted by the flooding brought on by stronger-than-expected rainfall and king tides, the highest tides of the year. Scientists say these tides, which occur every November, December and January when the sun, moon and Earth align and create a stronger-than-normal gravitational pull, are a foreshadowing of the future in our warming climate. The high tides of today will become the daily tides of the future.

“It’s hard for everyone to imagine the worst,” Corte Madera Mayor Rosa Thomas said. “People have told me leading up to this, ‘It’s come only this far up my driveway, or that far up my driveway, so I don’t have to prepare for anything more,’ and I think people have to realize that there’s a first time for everything.”

National Weather Service Warning Coordination Meteorologist Brian Garcia said the weekend’s storms outperformed his office’s predictions, but that they weren’t out of the realm of possibilities.

“The modeling is based on what we’ve seen in the past, what the physics say, but the climate is changing,” he said, noting that the Bay Area has seen sea level rise of nearly 2 millimeters per year in recent years. While seas have risen only about 8 inches since the 1880s, the ocean and the bay could rise by about a foot by midcentury and more than 6 feet by the end of the century — thanks mainly to human-caused climate change.

King tides in the region were already at a 28-year high, at 2.5 feet above ground level according to the weather service’s tidal gauge in San Francisco, and Friday and Saturday’s showers dumped more than 2 inches of rain across areas of Marin, and even more in coastal regions. Strong winds created an additional storm surge, forcing even more water onto land as rain turned streets into rivers.

“We’re seeing stronger storms as we go forward, and the predictions are that we are going to continue to see more intensity in the storms and wilder swings,” Garcia said.

That could mean more flooding situations like last weekend — and more significant ones, since the system was not classified as an atmospheric river, which are common during Bay Area winters and can be marked by higher rainfall totals.

“An atmospheric river could have made this a lot worse,” Garcia said.

Still, the scale of the flooding alarmed North Bay Rep. Jared Huffman, who toured some of the county’s flooded areas on Monday.

“In almost every direction in a place like Marin County, you’ve got vulnerability,” he said. “I hope we don’t have to see catastrophic damage to have a greater commitment to resiliency.”

Water seeped around numerous retail and residential areas in low-lying parts of Marin County, including the Larkspur Marina neighborhood, which sits along the Corte Madera Creek.

“The streets looked like a lagoon,” Larkspur Mayor Stephanie Andre said.

Water pooling on major thoroughfares also caused major delays along Highway 101 over the weekend, after about 2.5 feet of water quickly rose along the route, Thomas said. Exits had to be shut down for multiple hours because of standing water.

As rain continued on Monday, the highway’s northbound off-ramp to Highway 1, which leads to Sausalito, was again closed due to flooding.

Thomas said when rain, king tides and storm surge all combine, the impacts don’t just harm those bayfront properties, but “tie up the entire town.”

“That is a call for us to be united in tackling this,” Thomas said. “It’s a county problem, and we have to approach it that way. And we all have to participate in the solutions together.”

The state has tasked every county and city around the lip of San Francisco Bay and the coast to come up with a sea level rise plan by 2034. The solutions should ideally deal with today’s flooding and the high water of the future.

Thomas said Corte Madera has a climate action plan to address related issues, like increased flood risk, and is looking at creating physical barriers that can help reroute water. In 2023, the city held a listening tour to develop a community vision for adaptation to a future with rising sea levels.

In Larkspur, city officials attempted to get extra pumps into residential areas to drain flood water, but Andre said that pumping isn’t effective during elevated tides. She said that the city is hoping to work with Huffman to secure funding to strengthen some of its coastal retaining walls, especially as Marin continues to deal with sea level rise.

One neighborhood had applied for $18 million in federal grant funding to build a new sheet pile wall meant to keep water out. County supervisor Mary Sackett said the current 40-year-old berm wouldn’t be able to stop any overtopping of floodwater, threatening homes and the entire road system around Vendola Drive in Santa Venetia, a community in eastern Marin. Like many federal grant programs, issuance of that money has been paused for months under President Donald Trump.

Even if it did become available, though, it won’t be enough to cover the full cost of the project, and, Huffman said, it “is not sustainable in the long term, especially with these tides and all of the volatility with our weather.”

“We’re not going to give up on funding that longer-term solution,” he said.

What those more lasting solutions might look like, local leaders don’t really know. Sackett said the focus is often too local on how to prevent disaster in one city or neighborhood. She said the more pertinent question that needs answering is: “How do we make this entire area more resilient?”