A 45-foot sinkhole has opened up beneath a storage pond at a fertilizer plant in central Florida, causing more than 200 million gallons of contaminated waste to leak into one of the state’s main underground sources of drinking water, the Orlando Sentinel reports.

The massive sinkhole is believed to connect to the Floridan aquifer, which underlies all of Florida as well as southern Alabama, Georgia and South Carolina. An aquifer is an area of permeable rock that absorbs and holds vast amounts of water. A sinkhole is caused by a collapse of the surface layer of rock.

The plant is operated by the Mosaic Co., the world’s largest supplier of phosphate. The company said on its website that it discovered the sinkhole in late August at its New Wales facility after noticing water levels had dropped in a stack of radioactive waste product known as phosphogypsum. The 215-million gallon storage pond that sat atop the waste mineral pile is now dry.

According to the website, Mosaic immediately implemented additional and extensive groundwater monitoring and sampling regimens and has found no offsite impacts. The water is being recovered by pumping through onsite production wells.

“We are working closely with regulators and have been reporting to FDEP daily,” the company website says. “We have also called in top experts in the field to advise us on this issue. Enhanced water quality monitoring continues, and we are developing a comprehensive corrective action plan to address and rectify the cause of the water loss.”

FDEP is the Florida Department of Environmental Protection, which is performing frequent site visits.

“Groundwater moves very slowly,” David Jellerson, Mosaic’s senior director for environmental and phosphate projects, told the Orlando newspaper. “There’s absolutely nobody at risk.”

The cities of Tallahassee, Jacksonville, Gainesville, Orlando, Daytona Beach, Tampa, and St. Petersburg all rely on the Floridan aquifer, which also supplies water to thousands of domestic, industrial and irrigation wells throughout the state.

The Orlando Sentinel said the incident comes less than a year after Mosaic settled a massive federal environmental lawsuit with the U.S. Environmental Protection Agency in which the company agreed to pay nearly $2 billion in fixes, improvements and cleanups at its plants.