Al Wehrmann, PE, PH, DWRE and Jack Wittman, PhD, PH of INTERA’s Midwestern Division were part of a team that successfully obtained a sole source designation for the Mahomet Aquifer System located in east-central, Illinois. The sole source aquifer designation was granted by the U.S. Environmental Protection Agency (EPA) because contamination of the Mahomet Aquifer system would create a significant hazard to public health since there are no other feasible alternative sources of drinking water for the people that currently rely on the aquifer. The designation authorizes the EPA to review projects that receive federal financial assistance to ensure that they will not contaminate the aquifer. In addition to the Sole Source designation, INTERA staff have been working with the Illinois State Water Survey, the Mahomet Aquifer Consortium, and other regional planning representatives to evaluate the water demand model constructed in 2008 that estimated current and future withdrawals for the region in east-central Illinois. An analysis of the predicted demands for 2010 based on growth rates and water withdrawal data for the region was also conducted.