EPA announces final cleanup for water aquifer on Tohono O’odham Nation

TUCSON — The U.S. Environmental Protection Agency (EPA) has finalized its plan for the cleanup of the Cyprus Tohono Mine Site Basin Fill Aquifer under the Superfund law.

The newly signed Record of Decision outlines a cleanup plan which will use reverse osmosis treatment for groundwater contaminated with perchlorate, uranium, and sulfate, and will restore groundwater as a drinking water resource.

The Cyprus Tohono Mine Site is located on the Tohono O’odham Nation near the Village of North Komelik, about 30 miles south of Casa Grande. Mine waste which caused the groundwater contamination was removed in 2008, but an approximate 4-mile-long plume of groundwater polluted by perchlorate, sulfate, and uranium remains in what is known as the Basin Fill Aquifer. This aquifer was formerly a drinking water source, but alternative drinking water is currently being supplied to nearby residents due to its contamination.

“Ensuring access to clean and safe drinking water is one of EPA’s most important missions,” said EPA Director of Region 9 Superfund and Emergency Management Division Michael Montgomery.

TUCSON — The U.S. Environmental Protection Agency (EPA) has finalized its plan for the cleanup of the Cyprus Tohono Mine Site Basin Fill Aquifer under the Superfund law.

The newly signed Record of Decision outlines a cleanup plan which will use reverse osmosis treatment for groundwater contaminated with perchlorate, uranium, and sulfate, and will restore groundwater as a drinking water resource.

The Cyprus Tohono Mine Site is located on the Tohono O’odham Nation near the Village of North Komelik, about 30 miles south of Casa Grande. Mine waste which caused the groundwater contamination was removed in 2008, but an approximate 4-mile-long plume of groundwater polluted by perchlorate, sulfate, and uranium remains in what is known as the Basin Fill Aquifer. This aquifer was formerly a drinking water source, but alternative drinking water is currently being supplied to nearby residents due to its contamination.

“Ensuring access to clean and safe drinking water is one of EPA’s most important missions,” said EPA Director of Region 9 Superfund and Emergency Management Division Michael Montgomery.