State regulators on Wednesday endorsed Plum Creek’s historic development plan for nearly 1,000 house lots, two large resorts and hundreds of thousands of acres of land conservation in the Moosehead Lake region.

Despite pleas and strong words from plan opponents, the Maine Land Use Regulation Commission did not make any substantial changes to Plum Creek’s unprecedented proposal during 17 hours of deliberations on Tuesday and Wednesday.

The commission plans to vote on and formally present Plum Creek with a list of largely technical and minor changes next week.

“It’s an all-or-nothing deal,” Catherine Carroll, LURC’s director, said Wednesday evening. “They have to accept these recommendations and say they can live with them.”

Plum Creek officials said they are cautiously optimistic that the plan will work for the company. “We’re hopeful,” said Luke Muzzy, one of the plan’s architects. “We’ve been working on this for four years … so we are hoping we can get it through.”

LURC is winding down its review more than 3½ years after Seattle-based Plum Creek first unveiled the largest development plan in Maine history.

Plum Creek is seeking LURC authorization to rezone roughly 16,000 acres in order to carve out 975 house lots and land for two resorts near Maine’s largest lake. The proposal also includes a package of conservation deals that will guarantee public access and commercial forestry on roughly 400,000 acres in the region.

Commissioners reiterated this week that the privately negotiated conservation deals — which will net Plum Creek $35 million — are critical to LURC approval of the development plan.

Not surprisingly, the commission’s endorsement did not sit well with the organizations that have steadfastly criticized Plum Creek’s proposal.

“I think Maine people really need to question whether this process worked,” said Cathy Johnson of the Natural Resources Council of Maine. “The commission clearly did not listen to the Maine people who said Lily Bay is not an appropriate place for development.”

Plum Creek’s proposal for more than 400 housing units — including a 250-accommodation resort — near Lily Bay State Park generated the most controversy in a proposal that has deeply divided Mainers.

Hundreds testified during public hearings last winter with supporters and opponents represented in roughly equal proportions. Thousands more from Maine and throughout the country have shared their thoughts, hopes or fears about Plum Creek’s plan in letters, e-mails and petitions.

Supporters predict the planned growth, high-end resorts and guaranteed public access to more than 400,000 acres of forestland will help rejuvenate one of the most scenic yet economically distressed areas of Maine. Without the 30-year concept plan, LURC would have far less control over where development occurs and the 430,000-acre conservation deal would be off the table, supporters say.

Plum Creek’s critics, however, envision sprawling subdivisions for wealthy out-of-staters spoiling the wilderness character of an area many consider to be the jewel of Maine’s North Woods.

They predict untold numbers of moose, deer and federally protected Canada lynx will die on local roadways due to the thousands of additional cars Plum Creek’s plan will draw to the area daily. Water quality and recreational fisheries could also suffer from the pollution caused by subdivisions, cars, boats and jet skis, critics say.

Opponents have managed to force significant changes to Plum Creek’s plan.

The company negotiated the two private conservation deals with The Nature Conservancy, the Appalachian Mountain Club and the Forest Society of Maine after the public demanded more land protection.

Plum Creek also shifted 180 house lots away from the water and relocated one proposed resort to Big Moose Mountain, an area just west of Greenville that already has a ski facility.

LURC staff reduced the number of lots on Long Pond and sharply decreased the amount of land near Lily Bay on which Plum Creek could build. The commission also tightened up language on other industrial uses — such as wind farms, water extraction and gravel mines — that would be allowed on conservation land.

But the plan’s critics failed to convince the commission on two key points: that 975 house lots was excessive and that Lily Bay was an inappropriate spot for a resort and houses. This week, groups accused the commission of placating Plum Creek in order to secure the conservation deals.

“It is not your role to negotiate the best deal that Plum Creek will give you,” Phil Worden, an attorney with the Forest Ecology Network and RESTORE: The North Woods, said Tuesday.

Most of the commissioners described the Lily Bay developments as the most difficult part of the plan to stomach. But LURC has recommended adding additional checks and balances to ensure the agency has control over the size, scope and appearance of those developments during subsequent reviews.

LURC staff and board members also said their concerns about impacts at Lily Bay were tempered by the fact that much of the surrounding forestland would be placed under permanent protection.

“The commission feels that based on the rules in [LURC’s] comprehensive plan, they have no choice but to approve some development at Lily Bay,” Carroll said. “They just want to make sure it is done right.”

Concept plan approval is just the first of numerous regulatory hurdles Plum Creek or developers would have to overcome before building anything. LURC would still review each subdivision and resort before issuing permits, and any development near Lily Bay would be subject to even stricter oversight.

If Plum Creek accepts the recommendations endorsed Wednesday, LURC staff will work with the company to write a final plan to be presented to the commission early next year. Opponents are widely expected to appeal the decision to Maine’s Superior Court.