PORTLAND — The Land Use Regulation Commission didn’t violate procedural rules in approving a massive residential development in the Moosehead Lake region, the supreme court ruled today, giving the green light to the project that covers thousands of acres in one of the state’s unspoiled regions.

The plan by Seattle-based Plum Creek calls for 821 house lots and two resorts with more than 1,200 housing units at Big Moose Mountain and Lilly Bay. It was approved in September 2009, nearly five years after the company announced plans to rezone nearly 400,000 acres.

Critics contended the regulatory agency violated its rules by allowing the plan to be amended, and a Superior Court justice agreed that the agency should’ve reopened the proceedings for further comment.

In a unanimous decision, the supreme court said LURC did nothing wrong.

“We conclude that LURC did not violate its procedural rules and did not otherwise err by approving the rezoning petition and concept plan,” Justice Jon Levy wrote in today’s decision.

LURC held four weeks of hearings on the Plum Creek plan in December 2007 and January 2008. There were 26 parties and nearly 170 witnesses during that phase of the process. More than 400 additional witnesses testified during four full days of public hearings.

Following those hearings, the commission developed amendments to Plum Creek’s proposed concept plan based on the evidence presented during the hearings. Critics said there should’ve been additional public hearings to allow people to voice their opinion on the amended plan.

Environmentalists were divided with the Natural Resources Council of Maine, Forest Ecology Network and Restore: The North Woods fighting the proposal in court, while The Nature Conservancy and the Forest Society of Maine supported the plan because of conservation easements.

The approved development plan limits housing development to 16,900 of the 400,000 acres, and Plum Creek plans to donate or sell conservation easements on 363,000 acres where public access would be guaranteed and future residential development would be prohibited.