An icy Blue Hill Harbor sits in front of the town's wastewater treatment facility. The facility's outflow pipes gets blocked in extreme high tides and officials are working on plans to safeguard it as sea levels continue to rise. Credit: Ethan Genter / BDN

BLUE HILL, Maine — When extreme high tides roll into Blue Hill Harbor, officials know it’s going to cause problems at the town’s wastewater treatment facility.

Built along the harbor in 1975, the facility is one of the town’s most vulnerable assets and an example of public infrastructure in Hancock County — the county with the most coastline in Maine — that is at risk due to rising sea levels and climate change.

For the last few years, exceptionally high tides cause water levels to rise above the pipe that releases the final effluent from the facility. A chlorine tank where that effluent is disinfected is prone to back flooding in these tides, causing the filtration system at the aging facility to work overtime to get the seawater and effluent flowing back in the right direction.

The most recent example was over New Year’s weekend when an exceptionally high tide caused backups and even flooded the nearby town wharf. While these tides haven’t caused any major lasting damage yet, sea level rise predictions in the coming decades show more frequent flooding and problems are likely in store for the site.

“If we lose our wastewater treatment facility, it’s going to be detrimental to the town, to the hospital, to everybody involved,” said Shawna Ambrose, Blue Hill’s town administrator.

The ripples would also extend to neighboring towns that depend on Blue Hill’s grocery stores, schools and medical services.

“The other eight towns on the peninsula are all affected by one little wastewater facility in Blue Hill,” said Randy Curtis, a member of the Blue Hill sea level rise task force.

Town officials are looking at plans to safeguard the facility but expect it will cost several million dollars. Resolutions to its immediates issues are estimated to cost $3.5 million, according to an August report from Olver Associates. After that, estimates for the facility grow to more than $30 million for improvements over the next 20-plus years.

The small town is now facing big decisions on how to make and fund these fixes. Ambrose said the town could turn to reserves to help pay for it, use America Rescue Plan Act money or look for grants, but will most likely have to borrow money for the project.

The town is considering raising the facility, and Olver is expected to produce more detailed estimates on how much things might cost, Ambrose said.

Blue Hill is not alone in these decisions. A 2020 state report found that a 1.6-foot rise in sea level inundation flooding could cost wastewater treatment plants from York to Machias millions of dollars.

The Blue Hill sea level rise task force advised the town to be ready to manage 1.1 to 1.8 feet of sea level rise by 2050 and 3 to 4.6 feet by 2100 and prepare for scenarios about twice as high. Depending on how much sea levels continue to rise, the town wharf, fire station and a cemetery could all be in the line of fire, too.

Stonington’s downtown is right on the water and the island has been looking to bolster several of its roads, docks and other infrastructure against rising water levels and climate change. Transportation throughout the county is also a big concern, said Jarod Farn-Guillette, the executive director of the Hancock County Planning Commission.

He’s been developing maps that show public infrastructure at risk from rising tides, storm surges and sunny day flooding. They show several culverts are susceptible to flooding and could lead to certain areas being cut off.

“A lot of these smaller cross culverts from Penobscot to Brooklin to Segwick, it doesn’t look good,” Farn-Guillette said.