A massive sinkhole at a Florida fertilizer plant has caused more than 200 million gallons of radioactive water to leak into a main source of the state's drinking water.

The sinkhole, which measures 45 feet in diameter and is 300 feet deep, opened up beneath a pile of waste material at Mosaic, the world's largest supplier of phosphate.

A storage pond containing 215 million gallons of radioactive water sat atop the waste mineral pile and has drained into the Floridian aquifer system, which supplies drinking water to millions of residents.

Aquifers are vast, underground systems of porous rocks that hold water and allow it to move through the holes within the rock.

A massive sinkhole (pictured) at Florida fertilizer plant Mosaic has caused more than 200 million gallons of radioactive water to leak into a main source of the state's drinking water

The radioactive water has drained from the sinkhole (pictured) and into the Floridian aquifer system, which supplies drinking water to millions of residents

The Floridan aquifer, one of the highest producing in the world, is the principal source of groundwater for most of the state, and extends into southern Alabama, Georgia and South Carolina.

Mosaic said it is monitoring the groundwater and has not found evidence that any off-site water has been contaminated.

'Groundwater moves very slowly,' said David Jellerson, Mosaic's senior director for environmental and phosphate projects.

'There's absolutely nobody at risk.'

The sinkhole was discovered at Mosaic's New Wales facility in late August, after an employee noticed water levels had dropped in the pile of waste material known as phosphogypsum, according to Good Morning America.

It was discovered that the sinkhole damaged the phosphogypsum stacks, created during the processing of phosphate to make fertilizer, and the pond on top 'drained as a result'.

The pond on top 'drained as a result', taking gallons of acidic water, laced with sulfate and sodium, into the sinkhole, according to the Tampa Bay Times.

An unknown amount of the fertilizer byproduct, which contains low levels of radiation, also fell into the sinkhole with the water.

Mosaic said 'some seepage continues' but said it did not inform the public of the sinkhole for three weeks after the discovery because it found there was 'no risk'.

Mosaic said 'some seepage continues' from the sinkhole but said it did not inform the public of the sinkhole for three weeks after the discovery because it found there was 'no risk'

The sinkhole was discovered in late August, after an employee saw water levels dropped in pile of waste material known as phosphogypsum, which contains low levels of radiation

'The water is safe to drink and it will remain safe to drink', Jellerson told WFTS.

But nearby residents remain less convinced.

'The first word that comes to mind when you hear radioactive is cancer,' Melanie Wood told the station.

'I'm concerned. Are my kids going to get sick? Am I going to get sick? My neighbor's pregnant, what's this going to do to her baby?'

Mosaic said it began diverting the pond water into an alternate holding area to reduce the amount of drainage when the problem was first detected.

The company said it has been sucking the contaminated water out of the aquifer and back into the plant 'through onsite production wells'.

'We have an extensive monitoring system,' Jellerson said. 'It's already indicating that it's recovering the material, but it will take some time for that process to complete.'

Mosaic said it is also offering free water testing services to residents who obtain their drinking water from wells.

Dee Ann Miller, spokeswoman for the state's Department of Environmental Protection, said the company is updating state and federal agencies on the situation.

'Along with reviewing daily reports, DEP is performing frequent site visits to make sure timely and appropriate response continues in order to safeguard public health and the environment,' Miller wrote in an email to the Associated Press.

'While monitoring to date indicates that the process water is being successfully contained, groundwater monitoring will continue to ensure there are no offsite or long-term effects.'

An unknown amount of the fertilizer byproduct also fell into the sinkhole with the water at Mosaic's New Wales facility (pictured)

The Polk County phosphate plant has continued to run after the discovery of the sinkhole.

Jellerson said that the pond with the sinkhole is 'now dry,' and that once the water that went into the deep hole is recovered, it will be reused in plant operations.

The incident comes less than a year after Mosaic settled a massive federal environmental lawsuit with the US Environmental Protection Agency.

EPA found that Mosaic improperly handled its facilities, which posed a threat to the environment and human health.

Mosaic agreed to nearly $2 billion in fixes, improvements and cleanups at its plants and publicly committed to becoming more environmentally friendly.

Environmental groups said the damage from the sinkhole could be severe, and it adds to decades of pollution from the phosphorous fertilizer industry in the state, a key center of phosphate mining.

'I wish we could say that watching an environmental tragedy unfolding at a Florida phosphate mining site was a new occurrence, but sadly it's happened repeatedly,' said Tania Galloni, an attorney with the Florida office of Earthjustice.