BATTLE CREEK, Mich. — Additional water quality monitoring conducted by the City of Battle Creek indicates total trihalomethane (TTHM) levels have declined at several monitoringater quality monitoring between required quarterly compliance tests. While these samples are not used to determine regulatory compliance, they provide valuable information about how conditions are changing throughout the water system.

The city's most recent quarterly compliance testing results, detailed in the June public notice, were collected in May. The next round of required compliance testing is scheduled for later this month.

Since those compliance samples were collected, the city has completed four rounds of additional monitoring throughout the water system. Additional monitoring conducted June 12 showed lower TTHM levels throughout the monitoring network. Elevated TTHM levels were first observed during the June 26 monitoring round and continued during the July 10 monitoring round.

Those increases coincided with a period of extreme summer heat, when higher water temperatures can accelerate the formation of TTHMs within drinking water distribution systems. The city's review also identified operational factors that may have contributed to the elevated readings, including changes to normal water circulation patterns in part of the distribution system.

In response, the city increased flushing activities, added targeted flushing in several areas, and adjusted pumping and storage operations to improve water circulation and turnover. The most recent round of additional monitoring, collected July 24, found lower TTHM levels at several locations that previously recorded elevated readings. All results from that monitoring round were below 80 parts per billion.

TTHMs are compounds that can form when disinfectants used to treat drinking water react with naturally occurring organic matter in the water. The city continues to work with the Michigan Department of Environment, Great Lakes, and Energy (EGLE), engineering consultants and technical experts to evaluate both short-term operational changes and long-term improvements to further reduce TTHM levels across the system.

Figure 1. Battle Creek monitoring locations. Additional TTHM monitoring results collected June 12, June 26, July 10 and July 24, 2026. A red vertical line indicates the maximum contaminant level (MCL) of 80 parts per billion. Battle Creek Site 1 reached 100 ppb on June 26, and Battle Creek Site 4 reached 96 ppb on June 26 and 100 ppb on July 10. All July 24 monitoring results were below 80 ppb.

Figure 2. Springfield and Emmett monitoring locations. Additional TTHM monitoring results collected June 12, June 26, July 10 and July 24, 2026. A red vertical line indicates the maximum contaminant level (MCL) of 80 parts per billion. Emmett Site 2 exceeded the standard with readings of 98 ppb on June 26 and 99 ppb on July 10. All July 24 monitoring results were below 80 ppb.

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