Apr. 17—The Maine House of Representatives on Wednesday backed legislation exempting sand dunes on Sears Island from environmental rules to authorize the state to grant a permit to build an offshore wind terminal.

By voting 77-65, the House reversed itself eight days after voting 80-65 to reject the legislation. A dozen lawmakers switched sides and yielded to Gov. Janet Mills on a key energy policy priority: putting Maine on the path of becoming an East Coast player in the generation of wind power from the Atlantic Ocean.

The Senate approved the bill on Monday.

Rep. Richard Campbell, R-Orrington, who backed the legislation, said he recently visited the area that he said the state has already prepared to serve as a port. “The site has all been engineered,” he said, with drainage, culverts and “field that has grown up on gravel.”

He reminded lawmakers that the bill would establish a $1 million Coastal Sand Dune Restoration and Protection Fund that the Department of Environmental Protection can use to pay up to 50% of eligible costs incurred in a project to restore, protect, conserve or “revegetate” a coastal sand dune system and up to 100% of eligible costs for projects relating to coastal sand dune systems.

House Minority Leader Billy Bob Faulkingham, R-Winter Harbor, who opposed the measure, said during a brief House debate that Maine’s environmental laws are important, “and Sears Island is a beautiful and pristine location.”

“I’ve seen the studies. If a port is needed, there’s other locations to look at,” he said.

Critics of the project have urged Mack Point to be used to avoid what they call the industrialization of Sears Island. But the Mills administration has said an advantage of Sears Island over Mack Point is that dredging will not be needed. Several opponents said they were torn between conflicting environmental benefits: protecting the sand dunes and capitalizing on Maine’s access to the Atlantic and harnessing powerful ocean winds to be transformed into clean energy.

Environmentalists on both sides of the issue say sand dunes on Sears Island protect buildings and infrastructure from waves and flooding while providing habitat for migratory shore birds and endangered and threatened species. Advocates of the project, however, argued the legislation affects a manmade sand dune system on four-tenths of an acre on state Department of Transportation land on Sears Island that was created by the construction of a jetty.

Mills announced in February her selection of Sears Island for Maine’s foray into wind power. She said then it was not an easy decision, and it quickly drew opposition from environmentalists who focused on the sand dunes, urging lawmakers to not approve a carve-out in environmental rules and instead turn to nearby Mack Point.

The 100-acre site on Sears Island was one of several reviewed for more than two years by Maine officials. Portland, Eastport and Mack Point — which also is in Searsport — also were considered.