Manatee County officials had ordered the evacuation of around 300 homes in the area on Saturday, due to "further collapse of phosphogypsum stacks".
According to the state department of environmental protection, a breach was discovered on Friday in one wall of a 77-acre reservoir with a depth of 25 feet that contains millions of gallons of water containing phosphorus and nitrogen from the old phosphate mine.
The heightened threat forced the evacuation of hundreds of homes. Some families were evacuated in local hotels.
Manatee County Administrator Scott Hopes said it could take between 10 to 12 days for the situation to stabilize, according to ABC affiliate WJXX.
The Florida Department of Environmental Protection says the water in the pond is primarily salt water mixed with wastewater and storm water. The water is slightly acidic but not to a concerning or toxic level, officials said.More news: NIH Testing Moderna Vaccine Against S. African Variant
Authorities are working to plug the hole and pumping water to ease the pressure in the pond, but have warned that dirty water could spill into the community.
Florida Commissioner of Agriculture Nikki Fried, noted that the leak is not the first at the property, in a letter to DeSantis on Saturday calling on him to convene an emergency session of the Florida Cabinet.
Part of the reservoir's retaining wall has shifted, raising the prospect of a complete structural collapse which would see 600 million gallons of water gushing into the surrounding area within minutes.
Crews have been discharging water since the pond began leaking in March.
Thousands of gallons per minute is currently being pumped out of the reservoir now to bring the volume of water down, while other workers have been charting the path to control the flow of the water. He added though, that "we are not out of the critical area yet". "So public health and safety is the top priority, and obviously, we want to protect in a way that minimizes any of the environmental impacts".More news: CDC says fully vaccinated Americans can resume low-risk travel
The Florida DEP Secretary Noah Valenstein said another pond has higher levels of metals.
The owner, HRK Holdings, did not respond to a request for comment on Saturday. State authorities say the water in the breached pond is not radioactive.
The ponds sit in stacks of phosphogypsum, a solid, radioactive byproduct from manufacturing fertilizer. Sam algal blooms can put humans to danger as well, if they come into contact with polluted waters, or if they eat contaminated fish.
There are 27 gypsum stacks across Florida, WFLA reported.
Hopes said the plan is not to fix the damaged reservoir liner.More news: If You're Fully Vaccinated, a New Thumbs-Up