Flooding in Jackson, Mississippi, a week ago, overwhelmed the city's main water treatment plant, leaving more than 150,000 state-capital region residents without safe water. According to Criswell, there is no timetable for restoring service.
"I think the most difficult part right now is that our flood maps don't account for excessive rain that comes in," Criswell said on CNN's "State of the Union" on Sunday. "And we're seeing these record-breaking rainfalls."
She added that climate-driven extreme weather can be difficult to predict, as can whether a city or town's infrastructure can withstand it.
"We have to start thinking about what the future threats will be as a result of climate change," Criswell said.
According to a 2020 flood risk assessment conducted by the nonprofit group First Street Foundation, which examined every property in the 48 contiguous US states, federal maps understate the number of homes and businesses in significant danger by 67%.
"Right now, FEMA's maps are really focused on riverine flooding and coastal flooding," Criswell explained. "We work with local jurisdictions to update the maps."
The Jackson water crisis exemplifies how America's water systems were designed for a climate that no longer exists. Underinvestment, crumbling infrastructure, and more extreme weather have also plagued the majority-Black city.
In Jackson, federal, state, and local officials have been distributing bottled drinking water while working to increase pressure and get the treatment plant operational.
On ABC's "This Week," Jackson Mayor Chokwe Antar Lumumba expressed "optimism" about progress toward restoring safe water within days.
"Even when the pressure is restored, even when there is no boil-water order." "The question is not whether these systems will fail, but when they will fail," he said. "There are so many failure points."
"We're seeing not only the effects of age...and wear and tear on our system, but also the effects of climate change," Lumumba added. "We have colder winters, hotter summers, and more annual precipitation, all of which are putting a strain on our water infrastructure."