Hurricane Irma is probably causing severe déjà vu for first responders at the Environmental Protection Agency. Only a week ago, Hurricane Harvey brought record-breaking flooding to the Houston area, home to at least 41 of the nation’s most hazardous toxic waste sites. Water inundated 13 of these so-called Superfund sites, and now risks poisoning surrounding floodwater, soil, and people—mostly low-income, minority people, according to one analysis. Now, another storm that defies precedent is headed toward Florida and the Carolinas. There are at least 80 toxic Superfund sites in Irma’s path.

This isn’t a unique problem when it comes to hurricanes. After Hurricane Sandy devastated New York and New Jersey in 2012, officials had to monitor 247 Superfund sites—one of which, the Gowanus Canal, overflowed into people’s homes. Nine Superfund sites were in the path of Hurricane Katrina, and several flooded. Thomas Burke, an associate dean at the Johns Hopkins School of Public Health who conducted an assessment of chemical exposures after Katrina, said these inundations very likely contributed to the mass of various chemicals found in soil and groundwater after the storm. “It’s hard to say for sure because there was not specific site evaluation data included in our assessment,” he said. “But absolutely, Superfund sites were a major potential source of soil and groundwater contamination. They always are after major hurricanes.”

But now that storms that are becoming more dangerous due to sea-level rise, a warmer atmosphere, and a warmer ocean, a growing number of polluted locations are at risk. In 2012, the EPA said that nearly a third of the nation’s federal hazardous waste sites were within a 100-year floodplain (an area with a 1-in-100 chance of a flood event in any given year, according to FEMA). Five years later, the number of Superfund sites has grown, and experts almost roundly agree that FEMA’s 100-year floodplain has been rendered obsolete due to climate change. Just look at Harvey, where more than half of the flooding happened outside of any flood zone—including FEMA’s so-called “500-year flood-zone,” where there’s supposed to be only a 0.2 percent chance of a flood happening. Three floods have happened in those 500-year zones in the last three years alone.

These supposedly rare floods are happening so often because rainfall is getting more intense due to climate change. But FEMA only relies on historical data—not projections for the future—to determine flood zones. This, according to Superfund experts, puts the EPA in a precarious position during hurricanes, for two reasons: first responders could be unaware of a toxic site’s vulnerability to flooding and not secure it properly before a storm hits; and the agency might approve cleanup plans that don’t consider flooding risk. “Flood maps are very important in informing the design, maintenance, and operation of remediation of a Superfund site,” Burke said. “If you’re in a flood-zone, effective cleanup is an entirely different challenge.”

Combine that with EPA Administrator Scott Pruitt’s climate denial, and some say that could be a recipe for a toxic disaster—if not during Hurricane Irma, then later on. “Addressing this threat effectively means acknowledging things are going to get worse with climate change,” said Peter DeFur, a longtime Superfund cleanup consultant. “Pruitt doesn’t want to address that.”