NORTHEAST HARBOR – One of the best-known islands in Blue Hill Bay, 435-acre Tinker Island, joined the protective umbrella of the Maine Coast Heritage Trust in the final days of 2000, the trust announced Wednesday.

As one of the largest remaining unprotected islands on Maine’s coast, Tinker was a valuable commodity for the conservation group.

“I think it’s fair to say that Tinker Island has been out there and on the radar screen for many, many years,” said David MacDonald of the Maine Coast Heritage Trust.

In 1999, conservationists feared for the island when the southern half of Tinker was sold for $3.5 million. The new owners, Ann Johnston and Pritam Singh of Hanover, New Hampshire, planned a 10-lot subdivision.

“MCHT was not willing to give up on an island with such scenic, ecological and historic value,” said Caroline MacDonald Pryor, senior project manager for the Trust. “We began working with owners of both northern and southern halves, and fortunately both families valued the island’s natural beauty.”

The Henry F. McKenney family agreed to sell the 235-acre northern portion of the island to the Trust in 1999, when the family patriarch died.

“Henry fully enjoyed nature and would be pleased to have Tinker Island kept in preservation,” said his widow, Eileen McKenney, who lives in Oregon.

McKenney offered to sell the property for an undisclosed sum, which has been described as “substantially less than its asking price.” According to the Trust, the purchase and continued stewardship of the northern half of Tinker Island will reach about $1 million.

Although funds for purchasing Tinker Island were not immediately available, the Maine Coast Heritage Trust’s leaders voted in November 2000 to go ahead with the transaction.

“This was a turning point for the island’s future and we couldn’t let the opportunity slip away,” Pryor said.

The Trust has since applied for a $600,000 grant from Land for Maine’s Future to help fund the Tinker Island purchase. An answer could come as soon as this month, the Trust said.

The 200-acre southern portion of Tinker gained similar protection when Johnston and Singh donated a conservation easement to the Trust on Dec. 27, 2000.

The easement states that the proposed Tinker Island subdivision will never be built. Only three residences, a caretaker’s cottage and a single dock may be built. And any construction that is visible from the public waters of Blue Hill Bay must exhibit traditional New England architecture.

The conservation easement also preserves 144 acres of the Tinker Island property in its natural, undeveloped state.

“Our vision is to own and manage part of Tinker Island in a way that respects its unique place in history,” Singh said.