Conservation groups have reached an $8.75 million agreement to buy 58,000 acres of oil and gas leases in the Noble Basin.

Three groups — Citizens for the Wyoming Range, Wyoming Outdoor Council and the Wilderness Society — have sought an agreement for years with Plains Exploration and Production Company, known as PXP. Conservationists fear development of the area in the Bridger-Teton National Forest south of Jackson in Sublette County would disrupt migration routes and wildlife habitat.

The Trust for Public Land stepped in to complete the agreement. The deal was done almost two months ago, but was kept secret because of confidentiality agreements, said Chris Deming, project manager with the trust.

“About a year ago we got asked to take a look at this for several reasons,” Deming said in an interview. “We’ve got history with these types of projects, and we have history with PXP.”

The trust was also the buyer of the Rocky Mountain Front leases in Montana. That deal was the most pertinent precedent to the Noble Basin buyout.

Gov. Matt Mead and others announced the agreement Friday at Snow King Resort.

Mead recalled his grandfather, the late Gov. Cliff Hansen, noting the beauty of the area as they drove by.

“This is historic,” Mead said to a room of about 150 people. “Someday there will be a grandfather out there with his granddaughter or grandkids, and there will be a point where that grandchild will see their first eagle or first deer or first moose. Or have a chance to go fishing there for the first time. I can’t place a money value on that, but I know that it is invaluable.”

A 2011 environmental study for the PXP leases proposed 136 gas wells and 17 pads. That plan would have required 29 miles of roads, pipelines, compressor stations and other industrial infrastructure. The plan drew 60,000 public comments when it was released.

The Noble Basin, which forms the headwaters of the Hoback River, is undeveloped except for some two-tracks.

Two development scenarios scheduled to be released by the Bridger-Teton National Forest this fall will now be put off, Bridger-Teton Supervisor Jacque Buchanan said.

“We are very pleased the groups came to a mutually acceptable agreement,” Buchanan said. “We have a lot of work on our plate, so this will give us that ability to move on to some other projects.”

Dan Smitherman, spokesman for Citizens for the Wyoming Range, has been the face of the movement to stop gas development in the Noble Basin since 2007.

“I think it’s the best possible outcome,” Smitherman said. “What it really represents is Wyoming people solving Wyoming problems. I’m just happy, I don’t know what else to say.”

PXP would not give an interview on the agreement, but Steve Rusch, vice president of environmental health and safety for the Houston company, did release a statement.

“From the first day the Legacy Act was passed, PXP has repeatedly stated our willingness to consider a buyout of our lease position if a valid offer was tendered,” Rusch said. “Today’s announcement fulfills that pledge.”

The 2010 Wyoming Range Legacy Act, which prohibits future oil and gas development on 1.2 million acres in the area, didn’t apply to the PXP leases because they were sold before the act was adopted.

Deming of the Trust for Public Land said conservation groups have until the end of the year to raise $4.05 million to seal the deal.

“It’s not already paid,” Deming said. “We have until the end of the calendar year to raise those funds. It’s a very compressed schedule.”

Lisa McGee, an attorney for the Wyoming Outdoor Council who has worked closely with Smitherman, said there are adjacent lands that are still threatened by energy development.

“I’m very excited,” McGee said. “There’s a couple loose ends in the Wyoming Range we still have to wrap up, but this is a great step forward.”

Assuming the Noble Basin buyout funds are raised in time, 21,000 acres of valid oil and gas leases will remain in the Wyoming Range.