ST. CHARLES, Mo. – The City of St. Charles and Ameren Missouri have reached an agreement granting the utility company access to city-owned property in order to monitor groundwater contamination at the Elm Point Wellfield.

The deal comes weeks after the Environmental Protection Agency directed the two sides to reach an access agreement. City officials and Ameren Missouri had been in negotiations since November 2022.

Ameren will conduct monitoring and sampling work under the oversight of the EPA, which previously ordered the utility to submit a plan for cleaning up the contamination by June 30. It’s unclear if that deadline will be pushed back.

Meanwhile, the city is setting up an eight-tank assembly to decontaminate and clean the water from the pumps. The price tag is expected to be $18 million. However, the city may not have to take on that financial burden alone.

The Missouri Legislature is weighing giving St. Charles a $10 million, interest-free loan to update the city’s water infrastructure. The city would have around 10 years to repay the money.

St. Charles Mayor Dan Borgmeyer said this is just a short-term solution. The long-term answer for the St. Charles water crisis would be to relocate the walls altogether, which could cost more than $50 million.

In February 2023, the EPA declared the Huster Road Substation near Elm Point was the source of contamination at the wellfield, confirming long-standing suspicions of city officials.

In the 1970s, Ameren Missouri used a scouring solvent called tetrachloroethylene to clean equipment at the substation, according to Paul Michalski, a senior hydrogeologist for 212 Environmental. Ameren attempted to degrade the chemical in soil and groundwater. Two carcinogens were created in the process—cis-1,2-Dichloroethene and vinyl chloride—both of which are harmful to human beings.

Ameren claimed at the time, “cleanup of the Huster substation has been successful in reducing on-site, and off-site impact from a cleaning produce last used decades ago.”

In January 2023, the EPA collected both ground and water samples from the Elm Point Wellfield. Lab results confirmed the presence of both of cis-1,2-Dichloroethene and vinyl chloride and identified the Ameren substation as the source.

The St. Charles Wellhead District is the primary source of drinking water for the city. At one point, the district was able to produce six million gallons of water per day for St. Charles. As of December 2022, production had been reduced to 1.5 million gallons. Officials have not said how much water the city can produce with just one active well.

Borgmeyer said 60% of the city’s drinking water comes from the pumps. The remaining 40% is purchased from other sources, like the City of St. Louis. The mayor said St. Charles has had to purchase about $2 million of additional water from St. Louis over the past five years.