Source Water Assessment Program (SWAP) & Mapping Tool

The 1996 amendments to the federal Safe Drinking Water Act (SDWA) required states to develop and implement a Source Water Assessment Program (SWAP) to protect our critical sources of public water supply (e.g., wellhead and watershed protection of public drinking water supplies) to assure safe and affordable sources of water are being utilized to serve the public. The purpose of SWAP is to:

  • Identify areas that supply drinking water to the public;
  • Inventory potential sources of contamination;
  • Determine the susceptibility of the source water to contamination; and
  • Inform the public of the assessment results.

More than 12 million people in Illinois rely on public water supplies for drinking water. Assessments will be conducted for all public water supplies in Illinois, including more than 1,700 community water supplies. In addition, approximately 3,800 non-community water supplies will be assessed. Illinois SWAP activities will be divided into the following areas:

  • Community surface water supplies;
  • Non-community surface water supplies;
  • Great Lakes (Lake Michigan);
  • Community groundwater supplies;
  • Non-community groundwater supplies; and
  • Mixed groundwater and surface water community.

SWAP will help communities make important decisions about how to protect their drinking water. By working to ensure safe drinking water supplies, the health and economy of the community - as well as the preservation of natural resources - will be greatly improved. In addition, investment in drinking water treatment will be sustained for a longer time period.

For more information regarding SWAP, please contact the Illinois EPA, Bureau of Water, Groundwater Section, at (217) 782-1020. Questions pertaining to non-community water supplies should be directed to local health departments or the Illinois Department of Public Health at (217) 782-4977.