Prairie Research Institute

Mahomet Aquifer

The Mahomet aquifer provides hundreds of millions of gallons of water every day to nearly 1 million people in East Central Illinois for residential, industrial, and agricultural uses. Protection and management of this groundwater resource is critical to maintain and grow the region’s economy.

Response Team Members

  • Chair: Rick Winkel, deputy executive director, Prairie Research Institute
  • Contact: Trish Barker, PRI associate director for strategic communication, or 217-200-2327
  • Steve Brown, chief scientist, Illinois State Geological Survey
  • Anne Huber, geologic information curator, Illinois State Geological Survey
  • Kisa Mwakanyamale, geophysicist, Illinois State Geological Survey
  • Jason Thomason, geologist, Illinois State Geological Survey
  • George Roadcap, hydrogeologist, Illinois State Water Survey
  • Walt Kelly, groundwater geochemist, Illinois State Water Survey

Activities & Reports

In June 2017, the response team organized a stakeholder workshop on The Future of the Science of the Mahomet Aquifer. Stakeholder input from this workshop was reported in ISGS Circular 594: The Future of the Science of the Mahomet Aquifer.

In June 2018, the response team compiled a preliminary review of previous recommendations for the Mahomet aquifer. This provisional information was provided to the Mahomet Aquifer Protection Task Force to aid its deliberations. Members of the response team provided information and expertise to the task force, informing its final report: Mahomet Aquifer Protection Task Force: Findings and Recommendations

Improving understanding of the Mahomet aquifer with electromagnetic mapping

Among the top recommendations of the Mahomet Aquifer Protection Task Force is a call to increase funding to PRI to support the use of helicopter-based time-domain electromagnetics (HTEM) technology to more accurately map and characterize the aquifer.

While we know much about the aquifer through data provided by water-well drillers and exploratory drilling for geologic mapping projects, many questions remain. HTEM technology could provide a detailed map of the Mahomet aquifer, allowing confident, science-based decisions that:

  • Protect public health
  • Assure adequate drinking water for future generations
  • Prioritize actions that remediate threats or reduce contamination risk
  • Target water use for economic development and public infrastructure investment

Just like an MRI or X-ray reveals the human body, HTEM reveals geologic materials hundreds of feet underground.

  • A coil wrapped around a non-metallic frame transmits an electric current, which creates an electromagnetic field in the ground.
  • Different geologic materials “carry” the electromagnetic energy differently, and those differences reveal the thickness, shape, and distribution of those materials in high resolution and three dimensions as the helicopter flies over the landscape.
  • High-precision instruments keep track of location, flight paths, depths, and other data needed to transcribe the measurements into data that show the underground geologic layers.

HTEM is cost-effective, efficient, and safe

  • HTEM is a non-destructive and non-invasive method of detecting aquifers that hold water.
  • Flight is quick, covers more acreage, collects more geologic information than working on the ground, and provides information about otherwise inaccessible areas.
  • The magnetic field generated by HTEM is approximately 100 times weaker than that created by a moving electric field and is not a risk to humans or animals.
  • The helicopter flies slow and low across the landscape at an altitude of about 150 feet following pre-planned, regularly spaced flight lines.
  • HTEM pilots are trained in specialty flight services. They are always prepared to land in unobstructed and unoccupied areas and do not fly over facilities that may be occupied by people.

The Illinois State Geological Survey has successfully used HTEM to map the thickness of the Illinois near-shore zone of Lake Michigan (funded by the National Oceanic and Atmospheric Administration). Other organizations have used this proven technology to:

  • Distinguish zones of cold fresh water, hot saline water, steam, clay and unaltered rock at Yellowstone National Park
  • Map the drinking water resources of the entire country of Denmark
  • Show hidden groundwater and ice in Antarctica (funded by the National Science Foundation)
  • Detect water under the volcano at Mount St. Helens
  • Map groundwater under the Galapagos Islands

For more information about HTEM contact