St. Charles restarts water treatment system after 2

A water well shut down in 2005 due to contamination stands in front of the Ameren Huster Road substation in St. Charles on Wednesday, Feb. 15, 2023.

ST. CHARLES — The city resumed using its water treatment plant late Tuesday night after a two-day shutdown, along with water from a city-owned well.

The closure had been due to a drop in the concentration of naturally occurring ammonia in well water that when mixed with chlorine produces the primary disinfectant in the city’s water distribution system, officials said.

John Phillips, the city’s utilities superintendent, said the plant, called Elm Point, was restarted after the city finished testing the use of liquid ammonium sulfate purchased from a supplier to make up for the decline in natural ammonia.

He said he didn’t know offhand the extra cost to the city. “We don’t know if this is a temporary issue or a long-lived issue,” Phillips said. “We’re going to use it as needed.”

During the shutdown, the city increased its ongoing purchase of water from the city of St. Louis. Before the shutdown, more than 80% of St. Charles’ water already was coming from St. Louis’ system.

St. Charles officials have said they believe that the sharp drop in naturally occurring ammonia is somehow due to Ameren’s latest efforts to remediate groundwater contamination at its substation in the city wellfield.

The city has asked the federal Environmental Protection Agency to do testing to see if that is the case. An EPA spokesman said Monday that the agency was in discussions with Ameren to identify what steps may need to be taken.

Though not ordered to do so by the EPA, the city over the past three decades as a precaution has shut down six of its seven drinking water wells because of the groundwater contamination and gradually increased its water purchases from St. Louis.

The EPA over the years has said the city’s water remains safe and that contamination in the wellfield hasn’t exceeded allowable levels.

St. Louis for decades has sold water to St. Charles and St. Peters, carrying water by pipeline from the St. Louis-owned Howard Bend treatment plant on the Missouri River in Chesterfield.

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