In a complicated $14 million land deal that took several years to negotiate, state officials are poised to complete Gov. Percival Baxter’s vision of a state park that encompasses both Mount Katahdin and the adjacent lake named for Maine’s highest peak.

The nonprofit organization The Trust for Public Land has secured an option to acquire the pristine, 700-acre Katahdin Lake and roughly 6,000 surrounding acres on Baxter State Park’s eastern boundary from a private timber firm, Gardner Land Co.

The national land conservation group then plans to donate the land to the Baxter State Park Authority.

But first, the land trust needs to raise an estimated $14 million by July to acquire the property, which includes hiking trails and paddling and fishing opportunities in one of Maine’s most scenic and unspoiled inland regions.

Gov. John Baldacci will join with representatives of the organization and other state leaders in Augusta today to launch the first-ever private fundraiser to benefit Baxter State Park.

“For the state of Maine, this is probably a once-in-a-century opportunity,” Patrick McGowan, commissioner of the state Department of Conservation, said Tuesday.

Indeed, it has been more than a century since Gov. Baxter first gazed at Mount Katahdin, an experience that launched a lifelong quest to preserve the land. Beginning in 1930, Baxter began buying up parcels surrounding Katahdin and transferring them to the state.

A 1921 map depicting Baxter’s vision for the park includes Katahdin Lake, which he called “one of the most beautiful of all of Maine’s lakes.” But Baxter never succeeded in acquiring the lake before his death in 1969. Subsequent efforts by the state to purchase the land also failed.

“Having the opportunity to complete that puzzle … is just a tremendous opportunity that we are all excited about,” said Sam Hodder, senior project manager for The Trust for Public Land.

Hodder’s group began talking with the property’s latest owner, Gardner Land Co., about three years ago. Gardner was planning to begin harvesting on the land, which includes the largest stands of unprotected old-growth trees in the state.

The resulting agreement is a complicated combination of land purchases and swaps that will give the state roughly 6,000 acres of relatively pristine wilderness and give Gardner access to healthy timberland elsewhere in the state.

As a precursor to the Katahdin Lake deal, The Trust for Public Land acquired valuable working forest in other parts of Maine for Gardner. The conservation organization will use roughly half of the $14 million to offset the cost of that land.

About $5.5 million will go to the state, which has agreed to transfer to Gardner several state-owned lots in Penobscot, Piscataquis and Franklin counties. The state acquired those lots over the years and has been managing them for wood production, McGowan said.

The trust’s New England director, Whitney Hatch, called the deal “a significant endeavor” for the San Francisco-based organization, which has helped to complete more than 3,000 land conservation projects in 46 states.

The Katahdin Lake acquisition has drawn initial commitments of $3.3 million so far from private donors, according to the trust.

McGowan said he’s confident sufficient private funds can be raised for the purchase in the limited time allotted. Because the project completes Baxter’s vision of the park, it will have special appeal to corporate and other private donors, he said.

Legislative approval also will be needed to complete the transaction, but the deal has strong support of House and Senate leaders from both parties.

Tom Gardner, vice president of Gardner Cos., the parent company of Gardner Land Co., credited the land trust with helping negotiate with the state. He said the deal will help ensure work for the Lincoln-based logging company’s 200 employees.

“This is going to be great for my employees,” said Gardner, whose company owns between 150,000 and 175,000 acres in Maine. “This will allow them to keep operations going, to keep their families going and to keep fiber coming into the mill.”

Gardner and his father, William T. Gardner, also made news last fall when they announced another land swap near Baxter State Park with Burt’s Bees millionaire Roxanne Quimby. In that deal, the Gardners traded about 10,400 acres of environmentally sensitive land in Township 4 Range 8 northeast of Wassataquoik Stream for 14,000 acres of woodlands already bisected by logging roads in Township 5 Range 8 northeast of the Penobscot River’s East Branch.

In the agreement announced Tuesday, the Katahdin Lake property includes several leased camps, one of which dates back to the late 1800s and was visited by a young Theodore Roosevelt and other dignitaries. The state is expected to honor those leases, Tom Gardner said.

Incorporating the property into Baxter State Park will render it off-limits to hunters. Both McGowan and Tom Gardner said the land’s rugged terrain and climate make it less than ideal hunting ground. But the Department of Conservation plans to use the $5.5 million it will receive from the deal to purchase better hunting land in the state, McGowan said.

Jensen Bissell, director of Baxter State Park, called the property “remarkable” for its old-growth stands and pristine features. But because of limited access to the lake, he questioned whether the lake will experience a surge in use if the park acquires the land.

The park last expanded in 1997, when the authority bought a 2,669-acre parcel from Great Northern Paper Co. for $480,000. That purchase, according to Bissell, exhausted much of the park’s land acquisition account.