DPW issues water quality notices for three areas of Baltimore County
There are no immediate health risks in the affected areas of Sparks, Loch Raven-Hillendale and Bird River-Harewood Park.
Above: Elevated but not serious levels of TTHs were found in some local drinking water.
Baltimore Public Works has issued drinking water quality notices for Sparks, Loch Raven-Hillendale and Bird River-Harewood Park in Baltimore County after routine testing detected levels of Total Trihalomethanes (TTHMs) above federal drinking water standards.
There is no immediate health risk, and customers do not need to boil their water or take other corrective action, DPW says.
TTHMs are by-products that form when chlorine and another chemicals used to disinfect drinking water react with natural organic material in the water.
Less-than-normal rainfall, combined with high temperatures, has increased water temperatures in the Prettyboy and Loch Raven Reservoirs, according to DPW.
Warmer water promotes the interaction between chlorine and organic matter in the water, thereby increasing TTHM formation.
The testing that triggered tonight’s notice was conducted between July 2025 and April 2026.
It showed that the four-quarter average TTHM level exceeded the EPA’s maximum contaminant level set at 80 parts per billion.
Prolonged exposure to high levels of TTHMs may increase the risk of bladder cancer and cause adverse reproduction effects.
The averaged TTHM levels for each area were:
