This story was produced by KQED and Climate Central, a nonadvocacy science and newsgroup. Climate Central’s Sirui Zhu contributed.
Even on a good day, Miranda O’Connell finds it stressful to drop her children off at Mill Valley Middle School: There’s only one road in and out of campus, and to turn onto it requires crossing over a busy artery perennially clogged with traffic.
But every time the road in and out of the school floods, she said the kids are in danger.
Cars can’t reach the school, traffic backs up, and harried parents pull creative U-turns in a rush to get to work. “It just causes a huge safety mess,” O’Connell said. Her daughter recently graduated, and her son starts sixth grade at the school later this month. “The kids kind of end up jumping out at random spots on a very busy road.”
Nestled at the edge of Richardson Bay with Mount Tamalpais glowering to its north, the campus is abutted on two sides by a marsh, a creek and human-made channels meant to drain water away. Water in the channels flows in the wrong direction — from the bay toward the school — several times a year, inundating the drop-off zone, along with a parking area with permanent yellow and black signs posted above them warning parents to “PARK AT YOUR OWN RISK.”
“There are whole areas where you cannot pass a car or ride a bike,” she said.
This flooding is a major reason parents like O’Connell are upset that the district plans to rebuild the aging school in the same spot it’s been in for more than 50 years rather than finding a new site on safer ground.
Mill Valley Middle School is one of 52 Bay Area public kindergarten through 12th-grade schools that a KQED and Climate Central analysis found already face flood risks, as the effects of human-caused climate change raise water levels in the bay. The bulk of the at-risk schools are in Alameda, Marin and San Mateo counties, and most sit on low-lying land that was once marshland. Assuming moderate sea-level rise projections, the bay’s high tide line will rise precipitously by the end of the century, as will the number of flood-prone schools.
Unlike most schools, Mill Valley Middle School leaders must decide how to address the problem now. In 2022, Mill Valley voters passed the $194 million Measure G to modernize the city’s schools, and the district plans to use as much as $130 million to rebuild its middle school.
It won’t take much more sea-level rise to convert the school into an “island,” said Kevin Befus, assistant professor at the University of Arkansas Department of Geosciences who has extensively studied the hydrogeology of the Bay Area. “Administrators will have to be keeping track of king tides and the size of storms coming through,” Befus said, and perhaps institute “high-water days,” where students learn remotely or take the day off entirely.
The Mill Valley School District shares the concerns about flooding, and board members said they’re determined to rebuild the school in a way that will keep its students safe.
Climate scientists like Befus said the ability to plan for the school’s future as seas rise is a preventative measure — or a luxury — that most schools lack.
To identify schools at risk of flooding, KQED and Climate Central compared the locations of more than 1,700 public and public charter schools in the Bay Area with flood risk data maintained by the U.S. Geological Survey. The analysis showed seven Bay Area schools currently have a high risk of coastal flooding, in which the ocean laps over the shoreline, with 10 more expected to run that risk by 2050.
The analysis also considered groundwater flooding, in which rising sea levels force salt water up into the soil, pushing the shallow groundwater to the surface, flooding property and potentially damaging underground infrastructure. Fifty-two schools already face this risk, and by 2050, the threat will be heightened at most of those schools.
At that time, 16 schools — including Mill Valley Middle — carried both risks.
The danger of floods will be amplified by an additional threat that the analyses do not capture: intensifying rainfall. As pollution has trapped heat within the atmosphere, rainstorms have been dumping more rain on average per hour, overwhelming storm drains built for lighter rain and lower seas.
The Bay Area suffers from unique vulnerability to coastal flooding, a legacy of 19th- and 20th-century developers, including public agencies, farmers and investors. They piled rubble, rocks and dirt onto some 250 square miles of the bay’s wetlands to create more solid ground upon which new neighborhoods and other buildings went up. In addition to being low-lying, infilled land tends to sink or subside.
The “razor-thin margin” between dry land and the bay will become even slimmer as seas rise, said Patrick Barnard, a research director for the USGS. “If it floods five times a year now, it’s probably going to be 20 times in 2050.”
For instance, Mill Valley Middle’s chronic flooding woes currently plague its access road and part of its parking lot. By the end of the century, major storms coinciding with king tides could inundate more of the campus.
At least two other schools within five miles of Mill Valley Middle also routinely fight off flood water.
A parking lot at Larkspur’s Redwood High School ponds with water so frequently that the school has installed pumps to keep it dry, said David O’Connor, the district’s senior director of maintenance and operations. Tamalpais High’s parking lot sits below the bay’s high tide levels, causing the storm drains to sometimes run backward from the bay onto campus, O’Connor said.
Experts point out that protecting public schools against rising tides and other climate hazards could offer community-wide benefits: gymnasiums could serve as neighborhood shelters, fields as retaining ponds for flood water, and surrounding roads safe evacuation routes.
Turning such a vision into reality would require systematic, significant updates to at-risk schools. However, no state or federal entity is charged with tracking flood-prone schools or providing them with adaptation funds.
(Map produced by Matthew Green/KQED)
That leaves districts to fend for themselves, which works out better for some than others. In California, money for school improvements almost always comes from local bond measures matched with state funds, a system that favors wealthy communities over poor ones.
For schools without resources to protect themselves, flooding will likely become a way of life. “Those who can afford to protect themselves will, and those who can’t end up with the extra water,” Befus said of districts that can’t rebuild a school above future floodwaters.
Take Bahia Vista Elementary, in San Rafael’s Canal neighborhood, just five miles north of Mill Valley. It counts among the most flood-risky schools in the Bay Area and also the most economically disadvantaged: 98% of its students qualify for free and reduced lunch, compared to 7% of Mill Valley Middle’s students, according to state data.
Over the last 15 years, Mill Valley and San Rafael have raised the same amount of bond dollars for their elementary and middle schools, even though Mill Valley has fewer schools and about half the enrollment of its northern neighbor.
It’s not lost on O’Connell what a fortunate economic position her town is in.
“We’re a very well-resourced community. We have the means to take the time to plan, to think about where the right place for this is,” O’Connell said. “And if we can’t do it, how do we expect under-resourced communities to do it?”
For the concerned parents at Mill Valley Middle, the obvious solution is to rebuild the school on a less vulnerable site. But the Mill Valley School District Board ruled this option out, said Board President Sharon Nakatani, because the district doesn’t own a large enough parcel to accommodate a new school.
The other option, moving the middle school to an existing school site, would displace hundreds of other students and require updating schools not in the district’s current plan.
District officials acknowledge that rebuilding Mill Valley Middle School at its current site won’t be simple. Their own research warns of major flooding on campus in the coming decades if no action is taken to protect it.
Adding to the complexity, the 1970s-era school sits on top of a former city dump where some refuse was burned. Before the school was built, a 2-to-3-foot cap of soil was poured over the waste to keep toxic contaminants — primarily heavy metals — from escaping, and the school monitors methane levels under the campus.
Still, district officials insist it’s possible to rebuild the school in a safe way where it sits. The district has contracted an architectural firm, a project lead, a builder and an engineering firm to evaluate, design and construct a school that protects students and faculty.
Simultaneously, Nakatani said, the school district has begun an environmental review of the plans, scrutinizing the risks of sea-level and groundwater rise. Because the site was once a landfill, the California Department of Toxic Substances Control must also evaluate the project.
“It’s a challenging site, and we knew that from day one,” Nakatani said.
Nakatani said the idea is to elevate the school buildings 5 feet above the 100-year-flood line. The plan will likely include new on-site parking and a drop-off loop raised above current flood levels, though “actual elevations are to be determined.”
The school’s main access road, Sycamore Avenue, and the area that floods may remain at current elevations, though it’s too early in the design phase to know.
“We are doing everything we can on our property to address sea-level rise,” she said.
Nakatani recently met with some parents concerned about the site’s hydrology and said she is “taking their concerns seriously.” She also said the district knows it won’t be able to please everyone. The district hopes to open the new school in fall 2027.
Raising the campus alone may not be enough to protect its students, faculty and staff: If the campus is raised but the low-lying streets around it are not, it could be difficult or impossible to evacuate in an emergency.
The streets aren’t the district’s domain, however — the City of Mill Valley would have to raise them. City Manager Todd Cusimano declined an interview request, saying it “would be inappropriate for the city to comment on the middle school.”
Nakatani argued that while solutions for future sea-level rise are hyper-local, it shouldn’t be the schools’ responsibility alone to resolve them. “We need to figure this out together because it’s not just one jurisdiction’s problem,” she said.
This sentiment was echoed by a Marin County Civil Grand Jury report released in May, titled, in part, “We Cannot Run — We Cannot Hide.” It advises Marin County to establish an agency to require sea-level rise adaptation across the county because “the water has already arrived.”
Coordinated planning could also ward off the problem of individual properties or communities armoring themselves at the expense of their neighbors. Seawalls and levees can cause water to flow toward less protected areas. Hydrogeology researcher Befus noted that these barriers can also worsen groundwater flooding, preventing it from draining. “So then you have to pump that water out somehow,” he said.
The bay’s high tide line has already crept upward by 8 inches over the past century, and moderate projections show it climbing another 3 feet by the end of the century, inundating the region’s lowest-lying land unless it’s protected.
Parents like O’Connell argue that rebuilding the middle school elsewhere in town would be the best way to help future generations of parents during emergencies and protect the welfare of children inheriting a warming world.
“The kids are massively losing out, and for what?” O’Connell said. “To rebuild a building on a site where it shouldn’t be rebuilt. It just doesn’t make sense.”
What ultimately happens at Mill Valley could prove instructive to the dozens of other Bay Area schools that have just begun to cope with floods. “It would be a powerful thing if this became a case study and an example to other places on how to plan for sea-level rise,” Befus said.
To learn more about how we use your information, please read our privacy policy.