The United States Environmental Protection Agency (EPA) is investigating a reported leak at a CO2 sequestration well site operated by Archer Daniels Midland (ADM) in Decatur.

ADM’s CO2 program was the first in the country to utilize a Class VI well, which is designed to allow carbon dioxide to be pumped into underground rock formations. The idea is to store or sequester the CO2 there to reduce greenhouse gas emissions.

The leak has alarmed many in local communities because of the nearby Mahomet Aquifer. While the ADM leak is not expected to affect that aquifer, there is currently no permanent restriction on drilling similar CO2 wells over similar aquifers.

The Mahomet Aquifer, which supplies an estimated 100,000,000 gallons of fresh water per day to a large region of Illinois, has been designated by the US EPA as a “sole source aquifer.” According to the agency, the designation means that “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.”