Borden Chemical opened the industrial plant in September 1966 to process phosphate, a key ingredient in fertilizer. The site sat in Manatee County, near Port Manatee on the Gulf Coast. By 1986, it had been sold to FCS Energy, which was absorbed into Consolidated Minerals. By 1988, it changed hands again to Royster Phosphates. The trouble started immediately. In 1989, a leaking storage tank released sulfate and forced evacuations of the surrounding area. Two separate incidents in 1991 released sulfur dioxide and sulfur trioxide into the air, creating an acid cloud that killed three workers and sickened 30 people. The FBI seized company records in 1992. Royster Phosphates declared bankruptcy in 1993, and Mulberry Corporation bought the plant. Mulberry ceased operations in 1999 for lack of funds, then abandoned the site entirely in January 2001. Each owner left the contamination in place. Each bankruptcy passed the problem to the next buyer -- or to the public.

Phosphogypsum is the radioactive waste left over when phosphate rock is processed into fertilizer. It accumulates in enormous stacks -- flat-topped hills of chalky material that can cover hundreds of acres and rise tens of stories high. At Piney Point, the stacks enclosed reservoirs of wastewater containing nitrogen, phosphorus, ammonia, and trace amounts of radium and uranium. The wastewater was held in place by earthen dams lined with plastic. After Mulberry walked away, the EPA briefly stepped in, then handed oversight to the Florida Department of Environmental Protection through a court-appointed receivership. In 2006, HRK Holdings purchased the site from the government for $4.3 million, with the requirement that they maintain the stacks and contaminated water. In 2011, a spill dumped contaminated water into Bishop Harbor and Tampa Bay. HRK filed for Chapter 11 bankruptcy in 2012. Environmental advocacy group ManaSota-88 warned the EPA that the site posed risks of catastrophic failure.

On March 25, 2021, leaks appeared in the containment wall of a holding pool atop a phosphogypsum stack at Piney Point. The reservoir held wastewater from the plant's former operations as well as seawater from a dredging project at Port Manatee. The leak worsened over the following days. On April 1, residents were ordered to evacuate -- an estimated 316 households fell within the evacuation zone. Efforts to repair the containment wall on April 2 and 3 failed. Florida Governor Ron DeSantis declared a state of emergency for all of Manatee County on April 3 and ordered wider evacuations. To prevent the reservoir from collapsing entirely and sending a wall of contaminated water across the surrounding area, authorities began pumping wastewater directly into Tampa Bay. The worst-case scenario, DeSantis said in a press conference on April 4, was a catastrophic wave of contaminated water that could destabilize adjacent phosphogypsum stacks containing radioactive material.

The controlled discharge into Tampa Bay was an act of deliberate sacrifice: poison the bay now, or risk something far worse if the dam failed completely. The wastewater was not classified as radioactive, but it was loaded with phosphorus and nitrogen -- nutrients that can trigger devastating algal blooms in marine ecosystems. The pumping continued around the clock. Meanwhile, Manatee County commissioners voted to allow the contaminated water to be injected into deep wells, a procedure that had been banned when previously proposed by a prior owner because of the risk to the aquifer used for agricultural irrigation and drinking water. Scientists, environmentalists, and the public debated the tradeoffs. There were no good options. In February 2021, national environmental groups including the Center for Biological Diversity, Waterkeeper Alliance, and Sierra Club had already petitioned the EPA to strengthen protections around phosphogypsum stacks in at least 12 states.

Florida lawmakers secured $100 million to permanently close Piney Point and clean up the site. In August 2021, the Florida Department of Environmental Protection sued HRK Holdings for failure to operate the site safely. Officials stated that once the crisis was resolved, the reservoirs would be drained, filled, and capped. But closure has been slow. Although ordered shut in August 2021, the plant was not expected to close until at least 2025. Piney Point is a case study in what happens when industrial waste outlasts the companies that created it. Six owners in 55 years, three of them bankrupt, three workers dead, and a bay contaminated -- all from a single phosphate processing plant that nobody wanted to pay to clean up. From the air, the phosphogypsum stacks are visible as pale, flat-topped mounds near the coastline, an industrial scar on the edge of Tampa Bay that is still being written.