The Manatee County Central Jail is at the corner of an evacuation zone surrounding the old Piney Point phosphate mine, where about 300 million gallons of wastewater is threatening to breach a reservoir there and flood the surrounding area.
In a news conference Sunday, DeSantis said state and federal emergency teams are on stand-by at the Piney Point Reservoir.
Residents within a 1-mile radius of the plant were ordered to evacuate, and Florida Gov. Ron DeSantis declared a state of emergency Saturday in Manatee County as well as neighboring Hillsborough and Pinellas counties over the threat.
Officials tried to plug the hole in the 8m deep pond with rocks and other material, but were unsuccessful.
According to the Florida Department of Environmental Protection, the water in the pound is mostly saltwater mixed with stormwater and wastewater. "The water meets water quality standards for marine waters with the exception primarily of the phosphorus and the nitrogen", DeSantis said.
A significant leak at a large pond of wastewater threatened to flood roads and burst a system that stores polluted waters. The Florida governor declared a state of emergency on Saturday for Manatee County, where the plant is located. A portion of the containment wall in the reservoir shifted, meaning a collapse could occur at any time.
Scott Hopes, the acting administrator of Manatee County, warned on Sunday that modelling had suggested a full breach of reservoir walls would release a surge "as high as a 20-foot wall of water" into the area.
Instead, "we will be depleting the holding ponds of their water, and then we will be moving forward to a permanent solution into the future", he said.
Florida Governor Ron De Santis warns of flood threat Credit Chris O'Meara AP
Officials in Florida said in a statement that the primary concern from the collapse would be flooding.
County and state officials are now working to pump water out of the reservoir to reduce the quantity in the event of a breach. "We are not out of the critical area yet".
The Florida DEP Secretary Noah Valenstein said another pond has higher levels of metals. Therefore, again, the official said, this is not water they want to see leaving the site.
The U.S. Environmental Protection Agency has a coordinator on the scene to work with emergency management and provide support as necessary, said EPA spokeswoman Brandi Jenkins. "We can take care of nutrients in the environment ..."
But the EPA says too much nitrogen in the wastewater causes algae to grow faster, leading to fish kills.
A wall of contaminated water could flood the area if the breach in the pond at an old mine bursts.
The ponds sit in stacks of phosphogypsum, a solid, radioactive byproduct from manufacturing fertilizer.
Hopes said the plan is not to fix the damaged reservoir liner.