Hundreds of California and Bay Area Hazardous Sites Could Face Future Flooding

Power plants. Sewage treatment facilities. Fossil fuel ports. Radioactively contaminated sites. These are just a few of the 249 hazardous sites across the Bay Area that could flood as seas rise in the coming decades in the worst-case scenario, according to a new report published Thursday in the journal Nature Communications.

The researchers project that 5,500 hazardous sites across the nation could be at risk of coastal flooding by the end of the century. Around two-thirds of these facilities are at risk of coastal flooding within the next 25 years, during 100-year flood events. “Historically underserved communities” are more likely to live near hazardous sites prone to flooding, the scientists wrote in a preview of the study.

Researchers from Climate Central, UCLA, UC Berkeley and Nanjing University collaborated on the study.

“The motivation for the study is that sea level rise is rising quickly, often more than projected, and is anticipated to more than double by 2050 worldwide,” said Rachel Morello-Frosch, a professor of environmental science, policy and management at UC Berkeley.

Seven states account for almost 80% of the hazardous sites at-risk by the end of the century. California is among them with 471 locations. That’s if human-caused climate change continues unchecked. State scientists predict more than a foot of bay rise by 2050 and over 6 feet by the end of the century in the worst-case scenario.

The list includes facilities that pose a risk to public health and communities: contaminated sites, former defense sites, businesses that handle sewage, toxic waste, oil and gas wells and other pollutants.

“We could avoid some of this flooding if we were to stabilize and then reduce our greenhouse gas emissions,” said Lara Cushing, associate professor of environmental health sciences at UCLA.

But sea level rise won’t just mean water lapping over shorelines. As the bay rises, it will push groundwater up inland. The researchers noted that there could be more or fewer potential problem sites, as the study did not account for groundwater rise or the increasing intensity of storms.

Previous research examining rising groundwater found that more than 5,000 toxic sites may be impacted along San Francisco Bay alone. A KQED analysis from 2022 found that in the Bay Area community of West Oakland, more than 100 sites are at risk from both rising seas and groundwater.

The new count includes some of the region’s most contaminated sites, like the defunct Hunters Point Naval Shipyard. The U.S. Navy polluted the shipyard soil and groundwater with radioactive chemicals, heavy metals and petroleum fuels when it decontaminated ships, fouling the surface water and sediment in the San Francisco Bay, too. The Environmental Protection Agency declared it one of the nation’s most contaminated sites in 1989.

The research team found that neighborhoods most at risk have a higher “proportion of renters, households living in poverty, residents who identify as Hispanic, linguistically isolated households, households without vehicles, seniors, and non-voters than neighborhoods without at-risk facilities,” the scientists wrote in a press release.

Cushing said there could be as many as 300 fewer places at risk across the country if leaders and companies globally aggressively reduce emissions.

If people come into contact with floodwaters tainted by hazardous materials — sewage from wastewater treatment plants, heavy metals from refineries, or oils from fossil fuel facilities — the health impacts to people ramp up, said Sacoby Wilson, a professor of global, environmental, and occupational health at the University of Maryland.

In the aftermath of a flood, the “toxic soup” people may encounter could exacerbate health conditions. Wilson said exposure, depending on the chemical or sewage, during a flooding event near a hazardous site could lead to fevers, rashes, E. coli-related illness, and other symptoms.

“You have compounding vulnerability when it comes to their socioeconomic status and in some cases, the role of racism that led to that disproportionate burden,” Wilson said.

Federal lawmakers introduced legislation in July that, if passed, would set aside $5 million over the next year for the United States Geological Survey to study and map groundwater rise nationally through 2100. The agency would also need to identify priority areas that are at increased risk of flooding.