MOUNT DESERT — To comply with federal drinking water mandates, the Mount Desert Water District is spending $1.8 million to expand the Northeast Harbor and Seal Harbor water treatment plants to accommodate ultra-violet (UV) disinfecting equipment.
“It’s an additional form of treatment that (federal environmental officials) feel is something that should be done,” said water district general manager Paul Slack.
“Our primary disinfectant has been ozone, and now the primary disinfectant will become ultra-violet light, but we will continue to utilize ozone.”
UV light works as a disinfectant by emitting radiation that destroys bacteria and viruses in water.
The Hadlock ponds are the source of drinking water for Northeast Harbor.
Water for Seal Harbor comes from Jordan Pond.
Construction of the treatment plant additions began in October, and the UV systems are expected to be installed and running by next summer.