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Overview of the Drinking Water Sole Source Aquifer Program

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What is a sole source aquifer? 

EPA defines a sole source aquifer (SSA) as one where:

  • The aquifer supplies at least 50 percent of the drinking water for its service area
  • There are no reasonably available alternative drinking water sources should the aquifer become contaminated

What is the SSA program? 

The SSA program enables EPA to designate an aquifer as a sole source of drinking water and establish a review area.  EPA then reviews proposed projects that will both:

  • Be located within the review area
  • Receive federal funding

The review area includes the area overlying the SSA.  It may also include the source areas of streams that flow into the SSA's recharge zone.

EPA's review is intended to ensure that the projects do not contaminate the SSA.

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EPA’s authority to designate aquifers as sole source

The SSA program is authorized by Section 1424(e) of the Safe Drinking Water Act of 1974 (Public Law 93-523, 42 U.S.C. 300 et. seq), which states:

"If the Administrator determines, on his own initiative or upon petition, that an area has an aquifer which is the sole or principal drinking water source for the area and which, if contaminated, would create a significant hazard to public health, he shall publish notice of that determination in the Federal Register.

After the publication of any such notice, no commitment for federal financial assistance (through a grant, contract, loan guarantee, or otherwise) may be entered into for any project which the Administrator determines may contaminate such aquifer through a recharge zone so as to create a significant hazard to public health, but a commitment for federal assistance may, if authorized under another provision of law, be entered into to plan or design the project to assure that it will not so contaminate the aquifer.”

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