CASA GRANDE, Ariz. — The U.S. Environmental Protection Agency has finalized a plan to clean a contaminated aquifer on the Tohono O'odham Nation but it could take up to 30 years to complete.
A four-mile-long plume of groundwater near the Cyprus Tohono Mine Site, located about 30 miles south of Casa Grande, has been contaminated with uranium and sulfate after exposure to mine waste.
The aquifer had been a source of drinking water until residents were required to find an alternate source.
According to the EPA, workers started mining oxide ore from this site in the 1880s before the Cyprus Tohono Corporation started operating the property in the late 1980s.
Groundwater contaminants were discovered in the early 2000s, resulting in residents being given bottled water until 2003, the year that two new wells were installed a few miles south of the North Komelik village.
No active mining has occurred at the site since 2009, according to the EPA.
After years of studies and investigations, the EPA has officially settled on a plan to make the site's groundwater a drinkable water source.
The new cleanup plan will include treating contaminated water with a filtering process called reverse osmosis. The treated water will then be pumped back into the aquifer.
The EPA said this cleanup process is projected to take up to 30 years, plus an additional 20 years of monitoring the aquifer. Alternative cleanup plans could have taken much longer to complete, EPA records show.
More information on the project can be found here.
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