City officials said the Battle Creek water system remains under a drinking water standard violation for total trihalomethanes, or TTHMs, even though recent test results show improvement.

Mayor Mark Behnke reported that May quarterly testing indicates current TTHM levels at monitoring points no longer exceed the federal maximum contaminant level (MCL) of 80 parts per billion. However, the running annual average (RAA) — which averages the most recent four quarterly samples at each monitoring location — remains above the MCL because higher readings from earlier quarters are still included in the calculation. As a result, the violation remains in effect until older elevated results are replaced by consistently lower readings.

Behnke outlined corrective actions underway: adjusting treatment processes to reduce TTHM formation; completing the annual hydrant flushing program to remove older water and sediment; increasing sampling at the Verona Well Field and throughout the distribution system; conducting quarterly operational evaluations to assess water age and tank cycling; and replacing aging wells at the Verona Well Field to improve long-term water quality.

Impacted customers include water users in Battle Creek, Springfield, Emmett Township and portions of Penfield Township, the mayor said. A letter detailing the most recent results and ongoing efforts was mailed to impacted customers and is available on the city's website, battlecreekmi.gov. The mayor said the downward trend in recent samples is a positive sign but that the violation will remain until the RAA falls below the federal MCL.