A land conservation group has reached a long-sought agreement to prevent a gas drilling project near a southern approach to Jackson Hole and Grand Teton National Park by buying out a vast area of mineral leases.

The Trust for Public Land plans to buy out 58,000 acres of oil and gas leases owned by Houston-based Plains Exploration and Production Co. for $8.75 million, the San Francisco-based group tells The Associated Press.

The announcement opens a fundraising effort by the trust. Almost half the money needs to be raised if the deal is to be closed at the end of the year as the agreement requires.

PXP confirmed the agreement with the conservation group, set to be announced at a news conference later Friday in Jackson. Wyoming Gov. Matt Mead planned to attend.

“PXP has repeatedly stated our willingness to consider a buyout of our lease position if a valid offer was tendered. Today’s announcement fulfills that pledge,” PXP vice president Steve Rusch said in a statement.

The deal would end PXP’s plan to drill 136 gas wells near the Hoback River headwaters inside Bridger-Teton National Forest. Opponents said the project would pollute the air, harm wildlife and taint pristine streams in a rolling landscape of meadows and forest.

Eighty-five percent of the buyout acreage is within an area where the 2010 Wyoming Range Legacy Act prohibits future oil and gas development. The law doesn’t apply to the PXP leases.

The company acquired the Eagle Prospect/Noble Basin drilling leases a few miles south of Bondurant in 2005. The pre-existing leases were grandfathered in under the act.

The drilling project was located near a southern approach to Jackson Hole used by many visitors to Grand Teton and Yellowstone national parks.

Upon acquiring the leases, the Trust for Public Land intends to turn them over to the federal government to permanently retire them, said Deborah Love, the group’s Northern Rockies director in Bozeman, Mont.

“We’re respecting those leaseholder rights and we’re paying something for them. But also we’re ensuring that this incredible resource is protected,” Love said.

The trust has secured $4.5 million for the deal but needs to raise the other $4.25 million by Dec. 31, she said.

Low natural gas prices played a role in the agreement. Rusch said PXP has been shifting away from low-margin natural gas toward higher priced oil in recent years.

The company could have completed the project in an “environmentally sensitive manner,” but the trust’s interest was advantageous to everybody involved, he said.

The deal should encourage owners of a handful of much smaller leases within the Wyoming Range Legacy Act territory to sell or donate, said Love.

“I think the belief is that if you can buy out PXP, you’re essentially taking away the economic incentive for these other, smaller leases to kind of tag on,” she said. “Because the infrastructure costs are pretty big.”

The trust has played a key role in other major land conservation deals, including protections for more than 600,000 acres in the Northern Rockies, according to Love.

Citizens for the Wyoming Range, which opposed the gas project, endorsed the deal.

“We always felt like a lease buyout was the cleanest, and a win-win, solution. It’s a Wyoming solution to a Wyoming problem,” said group spokesman Dan Smitherman.