A contractor installed 144 LED streetlights throughout Harpswell in late October and early November, after delays in the project. The replacement of high-intensity discharge lights with more durable and efficient light-emitting diode fixtures will reduce the town’s carbon footprint and limit light pollution, while saving money on energy and maintenance.

The town contracted Maryland-based RealTerm Energy to install the cobra head-style fixtures on existing utility poles. RealTerm subcontracted the job to Maine-based On Target Utility Services.

The work started Oct. 26 and was “substantially complete” as of Nov. 7, according to Mark Carter, a RealTerm executive who lives in Pownal. Installation had been expected to start in July, but issues that included availability of the contractor and hardware pushed it into the fall.

The project will pay for itself in four years, according to Carter. The budget comes to $74,734, of which $64,094 will go to RealTerm and $10,640 to Central Maine Power Co. to acquire the old lights. The LED lights will use 69% less energy than the old lights, so the annual electricity bill will drop from $23,103 to $5,456, a savings of $17,647.

The town selected lights with a “correlated color temperature” of 2200 Kelvin, similar to the old lights but lower than most LED streetlights. Harpswell will be the first municipality in Maine to install 2200 K streetlights, according to Carter.

The International Dark-Sky Association recommends as low a color temperature as possible to minimize light pollution. Harpswell also followed the association’s recommendation to use “full-cutoff” fixtures, which direct light down and out, rather than up.

The town’s selections earned praise from the Brunswick-based nonprofit Southern Maine Astronomers.

Harpswell “has many beautiful open spaces from which residents and visitors can fully enjoy the magnificence of the night sky; your decision to limit the color temperature of your new LED fixtures will help ensure that for years to come,” Southern Maine Astronomers President Robert Burgess said in a letter to the Harpswell Board of Selectmen. “As an organization dedicated to sharing our interest in astronomy, including preserving our dark Maine skies, we sincerely appreciate your good actions and hope they will serve as a model to other communities undertaking similar streetlight conversions.”

The low color temperature means the streetlights will emit less light at the blue end of the spectrum.

“Less blue light means less scattering, which means less sky glow that could affect not only night sky viewing but also the habitats of countless creatures from insects to amphibians to mammals that depend on darkness for such things as protection from predators, to mating, to hunting for their survival,” Burgess said.

Burgess added that 80% of Americans cannot see the Milky Way.

“Your actions will ensure that Harpswell’s residents and visitors will not be among them, and that the awe of a star filled sky will continue to be theirs for generations to come,” he said.

The project is part of the town’s sustainability plan.