A coalition of environmental organizations is suing the state of Florida, the Manatee County Port Authority and the owners of Piney Point, the Manatee County phosphogypsum stack whose near-collapse in April led to the evacuation of more than 300 nearby households.

The lawsuit was filed by the Center for Biological Diversity, the Tampa Bay Waterkeeper, the Suncoast Waterkeeper, ManaSota-88 and the Our Children's Earth Foundation, and targets state and local agencies, as well as HRK Holdings, which purchased the property in 2006.

The lawsuit alleges that HRK and the government agencies ignored warnings from the United States Army Corps of Engineers that storing dredged material from the nearby port at Piney Point could lead to a breach in a liner in the phosphogypsum stack and possible contamination of nearby surface water and groundwater. In 2011, after the discovery of a hole in the liner, 169 million gallons of wastewater filled with phosphorous and cadmium was discharged into Tampa Bay, which, according to the lawsuit, "helped trigger" a harmful algal bloom in nearby Bishop Harbor, but the dredging project was allowed to continue.

"They should have known that the liner system was inappropriate for that site and they should have known that putting dredge material on top of those liners was a really bad idea," says Suncoast Waterkeeper founder Justin Bloom. "There were clear red flags, and time and again, they ignored good engineering guidance."

Citing the pending litigation, Florida Department of Environmental Protection press secretary Alexandra Kuchta declined via email to comment on the lawsuit: "We are reviewing the filed complaint and will respond through our legal action."

The lawsuit claims that in the years since the 2011 discharges, conditions at the site were allowed to deteriorate, leading to the crisis earlier this year, when 215 million gallons of wastewater were dumped into Tampa Bay in an effort to prevent the entire stack from collapsing. According to the lawsuit, the defendants' "handling, storage, treatment, transportation, and disposal of solid and hazardous waste at Piney Point may, and does, present an imminent and substantial endangerment to health and the environment."

The state has committed to clean up and close the Piney Point facility, pledging to put $100 million from the federal government's American Rescue Plan Act toward the project. Manatee County, meanwhile, has fast-tracked a plan to inject the remaining wastewater into a deep well in the state's aquifer.

But Bloom says few details about the state's plans have been released, and that a federal court should oversee the process.

"We don't have confidence in our regulators to do this in a thorough and comprehensive way that's going to be safe for the environment and communities that rely on the resources that are impacted by this," says Bloom. "Given the track record of them dropping the ball at Piney Point, we just don't have that confidence moving forward and think it's important for us to have a seat at the table to make sure these decisions are made with adequate public input and the best available science."