Three wells situated on the Miami Springs golf course have been closed for nearly six months owing to chemical contamination, according to the county.

The golf-course wells supply water to the Hialeah and Preston plants off Okeechobee Road. They were shut down last August after sampling results showed elevated levels of per- and polyfluoroalkyl substances, chemicals better known as PFAS. The chemicals have been used for decades in nonstick cookware, water-repellent clothing, carpets, and products that resist grease, water, and oil, according to the federal Agency for Toxic Substances and Disease Registry.

Doug Yoder, deputy director of the Miami-Dade Water and Sewer Department, tells New Times the water from the affected wells contained higher-than-recommended levels of PFAS. But locals likely never consumed water infused with that particular cocktail of chemicals because their drinking water is a mix that comes from multiple sources, he says.

"When blended with water from the other 20-plus wells that serve the Hialeah water treatment, the water from the plant was well below the [federal] health advisory level," Yoder says.

The State of Florida does not have its own PFAS safety standard and instead relies on the U.S. Environmental Protection Agency's guidelines, which recommend that municipalities maintain PFAS levels lower than 70 parts per trillion. Testing conducted on the three Miami Springs wells last July, however, revealed high PFAS readings of 184 parts per trillion, 182 parts per trillion, and 124 parts per trillion, according to county records.

Yoder says further testing is underway and results are expected in February.

Well-safety concerns at the site last cropped up in 2013, when a Miami Herald report showed officials discovered an unregistered 1,120-gallon diesel tank buried in the Miami Springs well field at the same level as the water supply.

PFAS have also been used in firefighting foam on military bases. In 2017, ProPublica published an investigative series, "Bombs in Our Backyard," detailing how the Pentagon, through its military bases, poisoned millions of acres and did not fully report the potential health consequences to those who came into contact with the chemicals.

One of the articles cited a nearly 900-page report in 2018 from the Centers for Disease Control and Prevention (CDC), which cited health consequences of high levels of exposure to these chemicals, including cancer, liver damage, decreased fertility, and an increased risk of thyroid conditions and asthma. High levels of exposure might also increase the risk of serious conditions such as high blood pressure and preeclampsia. The main ways humans are exposed to these chemicals are through eating food or drinking water, the CDC said.

Earlier this week, the advocacy nonprofit Environment Working Group released a report showing the organization's testing results from municipal water sources across the nation. The Miami area ranked third highest in the nation for PFAS levels.