Conservation groups have reached an $8.75-million buyout agreement with Plains Exploration and Production Company 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 with the company, known as PXP, for years. Conservationists fear development of the area in the Bridger-Teton National Forest just south of Jackson in Sublette County would further fray migration routes and wildlife habitat.

The Trust for Public Land stepped in to help complete an agreement for the deal. The deal had been completed for roughly two months, 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. “We’ve got history with these types of projects and we have history with PXP.”

A 2011 environmental plan for the PXP leases proposed 136 gas wells on 17 pads, but two alternative development were scheduled to be released by the Bridger-Teton National Forest this fall. The 2011 plan generated 60,000 public comments when it was released.

Dan Smitherman, a 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.”

Conservation groups have until the end of the year to raise about $4 million to seal the agreement. Gov. Matt Mead and others were scheduled to announce the agreement at 11 a.m. today at Snow King Resort.