USGS Report States Miami Water Supply at Greater Risk than Expected

U.S. Geological Survey (USGS) scientists have published a report stating that Miami's public water supply from the Miami-Dade Northwest Wellfield is at risk of contamination because of the proximity of lakes created from limestone rock mining activities, according to the South Florida Business Journal.

The report and a press release were issued Aug. 27. Litigation is ongoing over the U.S. Army Corps of Engineering's mining permits in the area.

In a responding press release, the Miami-Dade Limestone Products Association described the USGS report as "flawed and irresponsible."

According to the USGS press release, in 2004 scientists conducted experiments to determine how chemical contaminants and pathogens would move through the Biscayne aquifer. A report on the results was recently published in the Geological Society of America Bulletin.

A tracer solution was injected into the aquifer for one hour, and the solution was still detected about a week later in public water supply wells. "This indicates that if a contamination event occurs in the Biscayne aquifer that continues for days, weeks or months it has the potential to degrade water quality and could persist from years to decades," said Dr. Allen Shapiro, a USGS research hydrologist involved in the study, in the press release.

Of particular concern, the agency said, is the potential movement of pathogens in the groundwater, such as Cryptosporidium parvum, from limestone-rock mine lakes to the production wells.

But Kerri Barsh, an attorney representing the Limestone Products Association, responded in an Aug. 28 press release that monitoring data and a quarter-century of operations have "proven that the drinking water supply from Miami-Dade's Northwest Wellfield is, and will continue to be, safe and protected."

The USGS tests were taken into consideration by regulators years ago, Barsh pointed out. The association's press release said no Cryptosporidia have ever been detected in the mining lakes or groundwater wells. It alleges the USGS made "numerous errors," such as including unsupportable mathematical assumptions and a "seriously flawed experimental design" and using "more than one hundred times the amount of dye necessary to run a realistic test."

Source: South Florida Business Journal