Appeals Court Clears EPA Approval of Phosphogypsum Road Test at Polk County Fertilizer Plant

A federal appeals court has upheld the Environmental Protection Agency's approval of a project allowing phosphogypsum, the radioactive byproduct of phosphate fertilizer production, to be used as road construction material at a Florida industrial site. A three judge panel of the United States Court of Appeals for the Eleventh Circuit unanimously rejected a petition brought by the Center for Biological Diversity.

The approval at issue permits Mosaic Fertilizer to build a test road using phosphogypsum at the company's New Wales facility in Polk County. The road sits entirely on private industrial property rather than on a public right of way, a limitation that featured in both the agency's analysis and the court's reasoning.

The court held that the EPA did not violate its own regulations and that the agency's review and technical methodology were well supported, appropriately tailored and fully explained. That standard of review, deferential to agency technical judgment when it is adequately reasoned, decided the case.

What phosphogypsum is

Phosphate rock mined in Central Florida is processed into fertilizer using sulfuric acid. The reaction yields phosphoric acid and a solid waste stream, phosphogypsum, at a ratio of roughly five tons of waste for every ton of product. The material concentrates naturally occurring radium from the source rock, and radium decay produces radon gas.

Because of that radioactivity, federal rules have long required phosphogypsum to be stacked and managed rather than distributed into commerce, with narrow exceptions available through an agency approval process for specific proposed uses. The Mosaic road request moved through that process.

Florida holds the overwhelming majority of the nation's phosphogypsum. The material sits in engineered piles known as gypstacks, concentrated in Polk, Hillsborough, Manatee, Hardee and Hamilton counties, and the largest of them rise well above the surrounding flat terrain and cover hundreds of acres.

The agency's risk analysis

The EPA's approval rested on a quantitative risk assessment estimating lifetime cancer risk for several exposed populations. According to the figures described in the record, the agency estimated risk at less than one in one million for nearby residents and facility workers, less than two in one million for construction workers, and 2.7 in ten million for truck drivers hauling the material.

Those figures fall within the range the EPA has historically treated as acceptable for regulatory decisions of this type, generally described as a risk between one in ten thousand and one in one million depending on the statutory framework at issue.

The Center for Biological Diversity argued that the decision violated the controlling regulatory text or was arbitrary and capricious under the Administrative Procedure Act, contending that the agency did not adequately address phosphogypsum risk and relied on outdated data. The panel disagreed on each point.

Why Florida has a stack problem

The court decision matters less for the single road it permits than for what it signals about the pathway to reusing a waste stream Florida has accumulated for decades and has no plan to eliminate.

Gypstacks are not inert. They hold acidic process water on top, and that water must be managed indefinitely. The 2021 emergency at the former Piney Point facility in Manatee County, where a leak in a stack liner forced the controlled release of hundreds of millions of gallons of process water into Tampa Bay, demonstrated the consequences when management fails.

The state has since spent substantial public money on closing Piney Point, and the Legislature has directed attention to the long term liability posed by stacks whose owners may not survive as going concerns. Every ton of phosphogypsum that finds a use is a ton that does not need perpetual containment.

Opponents counter that distributing a radioactive material into infrastructure trades a concentrated, monitored risk for a dispersed, unmonitored one, and that a road built today may be excavated, repaved or demolished decades from now by workers who have no record of what is underneath.

What it means for Floridians

The immediate practical effect is narrow. The approved road is a test project on private industrial land, not a change to Florida's public road building standards. No county or the Florida Department of Transportation is authorized by this ruling to pave a public road with phosphogypsum.

The longer horizon is what residents of the phosphate district should watch. A successful demonstration project, with monitoring data showing performance consistent with the agency's modeling, is the predicate for broader requests. Those requests would each require their own approval.

Residents living near gypstacks have a more immediate interest in stack integrity and water management than in the road question. Those issues run through the Florida Department of Environmental Protection's permitting and inspection programs rather than through federal radiation rules.

Local impact across the state

Polk County is the center of Florida's phosphate industry and hosts the New Wales facility where the road will be built. The county's economy has been shaped by phosphate mining for more than a century, and the industry remains a significant employer alongside the logistics and agriculture sectors.

Manatee and Hillsborough counties carry the legacy of Piney Point and the industrial waterfront at Port Manatee, and residents there have been the most organized opponents of expanded phosphogypsum use.

Tampa Bay itself is the shared resource at risk. The bay has been the subject of a decades long restoration effort that produced measurable recovery in seagrass coverage and water quality, gains that nutrient releases can reverse quickly.

The regulatory road ahead

The Center for Biological Diversity has indicated it will continue pressing the issue through other channels, and options after a panel loss include seeking rehearing before the full Eleventh Circuit or petitioning the United States Supreme Court, though both are long odds in administrative law cases decided on deference grounds.

A more consequential venue may be the EPA itself. Federal rules governing phosphogypsum use are subject to rulemaking, and any broader change to what the material can be used for would go through notice and comment with an opportunity for public participation.

Florida's Legislature also retains authority over how the state permits and monitors stacks, and lawmakers have addressed the issue repeatedly since Piney Point. Interim committee meetings begin in November ahead of the session opening March 2, 2027.

How the approval process works

Federal rules generally prohibit the removal of phosphogypsum from stacks, with a narrow exception allowing the Environmental Protection Agency to approve specific alternative uses on request. An applicant must demonstrate that the proposed use is at least as protective of human health as leaving the material stacked.

The analysis is quantitative. The agency models radiation exposure pathways for each population that could come into contact with the material, including workers who handle it, drivers who transport it, construction crews who install it and residents who live nearby.

Exposure modeling of this kind depends on assumptions about how much time each population spends in proximity, what shielding exists, and how the material behaves over time. Challenges to such approvals typically attack the assumptions rather than the arithmetic, which is what the Center for Biological Diversity attempted here.

The Eleventh Circuit's holding that the agency's methodology was well supported, appropriately tailored and fully explained tracks the standard courts apply when reviewing technical agency judgments under the Administrative Procedure Act. Courts do not substitute their own scientific conclusions for an agency's when the agency has adequately reasoned its decision.

Florida's phosphate legacy

Phosphate mining has shaped Central Florida for more than a century. The Bone Valley formation, spanning Polk, Hillsborough, Hardee, Manatee and DeSoto counties, contains one of the world's most significant phosphate deposits, and Florida has been a major global supplier of phosphate fertilizer for generations.

The industry has left a physical footprint beyond the stacks. Mined lands require reclamation under state law, and reclaimed areas across the phosphate district now function as lakes, wetlands, pasture and residential development. The quality of that reclamation has varied with the era in which the mining occurred.

Water is the recurring flashpoint. Phosphate processing uses and produces large volumes of process water that must be contained, and the aquifer beneath the phosphate district supplies drinking water to millions of Floridians. Sinkholes opening beneath gypstacks have created direct pathways to the aquifer in past incidents.

The economic dimension complicates the politics. The industry employs thousands of Floridians in counties where alternative employment at comparable wages is limited, and phosphate fertilizer is a globally traded commodity essential to agriculture.

State regulation of the industry runs through the Florida Department of Environmental Protection, which permits mining operations, oversees reclamation and monitors stack integrity. Federal regulation, including the radiation rules at issue in this case, operates alongside it.

What residents can monitor

Florida's Department of Environmental Protection maintains public permitting and compliance databases where residents can look up facilities near them, review permit conditions and see enforcement history. Those records are the most direct tool available to someone who wants to know what is happening at a nearby industrial site.

Air and water monitoring data for permitted facilities is reported to regulators on schedules set in each permit. The reporting is not always easy to interpret without technical background, but the underlying data is public and organizations that track the industry translate it.

County level governments have their own role. Local comprehensive plans and zoning decisions determine what can be built near industrial operations, and county commission meetings are where those decisions are made with public comment periods attached.

Residents who observe conditions that appear abnormal, including odors, discoloration in water bodies or unusual activity at a facility, can report them to the state's environmental complaint line, which generates a record and can trigger inspection.

What's next

Mosaic will build and monitor the test road under conditions set in the EPA approval, and the resulting data will inform whatever comes next. Monitoring results of this kind are typically reported to the agency rather than published in real time.

Environmental groups will continue to press for public access to that data. Whether monitoring results become routinely available, or emerge only through records requests and litigation, will shape how informed the next round of this debate is.

For now, the state of play is clear: the EPA's approval stands, the project is limited to private industrial property, and the broader question of what Florida does with more than a billion tons of stacked phosphogypsum remains unanswered.