On March 11, 2015 EPA designated a portion of the Mahomet Aquifer system in east-central Illinois as a sole source aquifer. More than half of the population in east-central Illinois relies on the Mahomet Aquifer system as a source of drinking water. See Sole Source Aquifers for Drinking Water

The Safe Drinking Water Act gives EPA authority to designate all or part of an aquifer as a "sole source" if contamination of the aquifer would create a significant hazard to public health and there are no physically available or economically feasible alternative sources of drinking water to serve the population that relies on the aquifer. 

The designation authorizes EPA review of projects that receive Federal financial assistance to assess potential for contamination of the aquifer system that would create a significant hazard to public health.

• News Release: EPA Designates Mahomet Aquifer as "Sole Source" of Drinking Water in East-Central Illinois - March 11, 2015
• Federal Register Notice: Sole Source Aquifer Designation of the Mahomet Aquifer System in East-Central Illinois - March 19, 2015

• Mahomet Aquifer Responsiveness Summary (PDF)(8 pp, 501 K, March 2015)
  Sole Source Aquifer Petition for the Mahomet Aquifer System in East-Central Illinois
• Final Mahomet Sole Source Aquifer Project Review Area Map (PDF)(1 pg, 1 MB, Feb. 10, 2015)
  8.5" x 14"
• Mahomet Aquifer Support Document with Errata Sheet (PDF)(15 pp, 504 K, March 2015)
• Mahomet Sole Source Aquifer Designation Document Reference List (PDF)(11 pp, 144 K, March 2015)