In Hurricane Milton’s wake, toxic “gypstacks” threaten Tampa Bay area

By Shannon Kelleher

As southwest Florida reels from the impact of Hurricane Milton this week, the first hurricane to directly hit the Tampa Bay area in a century, environmentalists are bracing for another possible impact – the contamination of local waterways from towering stacks of toxic industrial waste in the storm’s path.

When phosphate is processed into fertilizers for farmland, enormous quantities of phosphogypsum are left behind as heaps of concrete-like waste called “gypstacks,” which are topped with liquid waste ponds. Most US phosphate production takes place in Florida, with 25 of the 30 gypstacks located in the Sunshine State – a quantity totaling over a billion tons. The waste contains heavy metals as well as radium, which decays into a radioactive gas that causes lung cancer, according to the US Environmental Protection Agency (EPA).

“We refer to [the stacks] as ‘Florida’s Mountains’,” said Ragan Whitlock, staff attorney for the environmental nonprofit the Center for Biological Diversity, noting that the heaps of toxic chemical waste are each hundreds of feet wide and hundreds of feet tall. “Lesser storms than hurricanes have created massive structural integrity problems at these stack systems,” he said.

Of Florida’s 25 gypstacks, 22 were “at least generally in Hurricane Milton’s track,” said Whitlock, with three located directly near the bay. Whitlock said he is worried about pollution from the stacks impacting both the bay and the Floridan aquifer, which almost 10 million people depend on for drinking water.

The largest US producer of phosphate fertilizer, The Mosaic Company, confirmed in an email Friday that stormwater at its Riverview site, where it stores toxic phosphogypsum waste from fertilizer production, made its way into Tampa Bay after a water collection system onsite became overwhelmed following the hurricane.

“At this time, we believe some of that impacted stormwater made its way to an outfall which discharges into Tampa Bay,” said the Mosaic spokesperson. “The issue was addressed yesterday and is not continuing. The volume may have been greater than the 17,500 gallon reporting standard.  We expect water quality impacts, if any, to be modest.”

Mosaic said in a September 30 statement that early assessments showed “limited damage” to its facilities following Hurricane Helene, a Category 4 storm that hit Florida on September 27, although its Riverview facility “experienced water intrusion caused by the storm surge.” In an early June statement, Mosaic said it was “prepped and ready” for hurricane season.