Florida Crisis Highlights a Nationwide Risk From Toxic Ponds

They are ponds the size of city blocks: Wastewater pits that hold the hazardous byproducts of coal. Lagoons brimming with diluted pig excrement. Vast pools atop stacks of radioactive tailings.

The risks posed by pools of waste like these, a common feature at thousands of industrial and agricultural sites across the country, have been brought into sharp relief by a giant wastewater pond in Piney Point, Fla., that in recent days had appeared in danger of catastrophic failure.

Officials on Monday said the threat of collapse had passed after an emergency effort had pumped millions of gallons of water out of the pond and into local waterways. The environmental effects of such a large release of contaminated water remained unknown. This past weekend, the specter of a deluge had prompted the authorities to evacuate hundreds of people from their homes.

Open-air ponds are vital to major industries, like livestock and power generation. But environmental groups say they pose major environmental, health and safety risks, whether from mismanagement, or, increasingly, from the effects of climate change.

“They’re just an irresponsible way to store very dangerous waste,” said Daniel Estrin, general counsel at the Waterkeeper Alliance, a clean water nonprofit group. “And with climate change, we’re going to see more frequent and stronger storms that are going to impact these sites.”

The Florida emergency, at a former phosphate mining plant south of Tampa, is particularly dire. There, a pool that initially held more than 400 million gallons of wastewater, with traces of heavy metals and other toxic substances, sits atop a pile of phosphogypsum tailings at least 70 feet tall. Tailings are waste that is left behind when ores from phosphate mining are processed to create phosphoric acid, an ingredient used in fertilizer.

For decades, the tailings, a radioactive wet slurry containing traces of radium along with arsenic, lead, and other elements, were placed in ponds and left to evaporate, leaving behind enormous stacks of phosphogypsum topped by water. The fear was that if the pond collapsed it could wash away the tailings, sending a “wall of water” over nearby homes and businesses.

The mounds of tailings like these, which are scattered across more than two dozen sites across Florida, are some of the tallest earthen structures in the state. Florida is the world’s largest phosphate-producing area, according to the E.P.A., and accounts for about 80 percent of the nation’s phosphate mining. The United States mines and consumes about 23 million tons of phosphate a year.

While phosphogypsum tailing stacks like the one at the Piney Point site are concentrated in Florida, thousands of industrial and agricultural open-air wastewater ponds dot the country. They include at least 70 phosphogypsum stacks, 700 coal-ash ponds near coal-burning power plants and thousands of agricultural facilities like the vast lagoons at large, industrial livestock farms.

Those agricultural pools generally have a striking bubble-gum-pink hue, a deceptively cheerful color that results from anaerobic bacteria that digest the fetid slurry, a mixture of water, animal excrement and chemicals.

Various efforts to strengthen federal oversight of manure lagoons have faltered, and most ponds are regulated at the state level. However, the Environmental Protection Agency has acted in some of the most egregious cases, ordering dairy farms to shore up their lagoons after tests showed elevated nitrate levels, which can harm human health, in residential drinking water wells.

In the early 2000s, the agricultural giant Smithfield Foods promised to study alternative ways to handle manure under an agreement with North Carolina. An expert appointed by the world’s largest pork producer, now a wholly-owned subsidiary of the Chinese meat and food processing company WH Group, came up with a number of different options, including one that would solidify the fecal waste, but none of those were found to be economically feasible.

Environmental groups recently petitioned the state to revisit the agreement. Smithfield has said it has already fully complied with the agreement’s terms. The company did not immediately provide further comment.

“It’s a model that needs to be revised — this large scale animal production model,” Ms. Williams said. “These are huge industries but they’re not regulated as industries. They’re still regulated as if they’re small farms.”

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