TROY – A portion of the city’s water system was found to have a reading that exceeded the state limit for a potentially hazardous chemical, total trihalomethane, while the city was upgrading water storage tanks in 2017, the city reported Tuesday.

The Department of Public Utilities reported an average annual TTHM reading of 81.6 parts per billion at Project Road. The state requires the city to report to its water customers a reading exceeding 80 parts per billion. A mailing is going out to all water users in the city.

The Project Road sample reading was made from water that comes from the 5 million gallon water storage tank at Peterson Court. It was 51.9 percent higher than the 2016 reading of 53.7.

Long-term exposure to TTHM has shown an increased risk for cancer, low birth weights, miscarriages and birth defects. TTHM occurs when chlorine used to treat water reacts with organic material.

Sampling at three other locations were all below the 80 ppb level. The readings were 76.6 ppb at Campbell Avenue, higher than the 2016 reading of 52.5 ppb; 74.7 ppb at Congress Street, higher than the 2016 reading of 51.1 ppb; and 78.9 ppb at Vandenburgh Avenue, higher than the 2016 reading of 63.3 ppb.

Public Utilities Superintendent Chris Wheland said recent quarterly readings indicate the TTHM readings are headed back below 80 ppb. The city had seen the surge in the readings when its treatment system to deal with TTHM contamination was offline for upgrades.

The city does quarterly testing as required and found the samples were elevated in the second and third quarters of 2017 when upgrades to the treatment system were being performed.

Information about the notification is available at the city website, www.troyny.gov. Anyone with questions regarding the situation may call the Department of Public Utilities at 518-237-0319.