A Pennsylvania environmental-advocacy group has come up with a plan to keep natural-gas drillers from bringing their rigs, trucks, pipelines, and noise into pristine state parks.

The short version: Get them to pledge not to do it.

John H. Quigley, former secretary of the Department of Conservation and Natural Resources (DCNR), which manages the parks, thinks the drillers have an incentive.

"Drilling in state parks is going to provoke public outrage," he said Thursday in announcing the plan, proposed by Citizens for Pennsylvania's Future and dubbed "Don't drill through the heart of Pennsylvania."

"I think, frankly, that the industry does not need the PR headache," said Quigley, special adviser for the environmental group, also known as PennFuture.

He said current horizontal drilling methods, which can extend laterally about two miles from a drill site, could give companies access to the gas by drilling in areas next to parks instead of on them.

Without commenting on the proposal directly, the Marcellus Shale Coalition, an industry group based in Canonsburg, released a statement.

"As former Gov. Ed Rendell and PennFuture's founder John Hanger said, 'Pennsylvania has the strongest enforcement program of any state with gas drilling. Period.' They're right, and our industry is committed to responsibly developing clean-burning, job-creating American natural gas," spokesman Travis Windle said in an e-mail.

Hanger, also the former secretary of the state Department of Environmental Protection, said of the proposed plan, "I oppose drilling in state parks. I support efforts to prevent it. These are smart ways of doing so."

A DCNR spokeswoman said the agency was reviewing the plan and could not comment.

More than half of the state's 117 state parks - 61 - lie atop the natural gas-rich Marcellus Shale formation. Overall, the state does not own the mineral rights to about 80 percent of state park acreage. It does not have the legal right to deny access to those that do.

"So there is a very real prospect of drill rigs puncturing parks, of roads and pipelines and storage areas gouging what I think are very precious public places," Quigley said. "The tranquillity of these refuges could be shattered."

PennFuture has written to five natural gas companies operating in Pennsylvania - Chesapeake Energy, Range Resources, Shell, Consol Energy, and EQT Corp. - asking them to pledge to protect the state parks.

None responded to requests for comment.

No state parks have been drilled in yet, Quigley said. But drilling has occurred in state forests, where about 700,000 acres, or one-third of the land, are vulnerable.

Last fall, Quigley visited one site in Tiadaghton State Forest, west of Williamsport. Even though the area was managed according to what he said were "strict" DCNR standards, the activity, he said, had turned a roughly 30-acre stand of forest into an industrial park.

"It was incredibly loud," he said. "And you could smell the diesel fumes."

The PennFuture plan also calls for legislation that would establish a 300-foot setback from park boundaries.

In cases where the natural gas is accessible only from within park boundaries, the plan asks the legislature to institute an impact fee.

Quigley said he didn't have a figure in mind, "but I will say that the intent here is that the fee should be substantial, if not prohibitive."

He said a precedent exists for the approach.

West Virginia, which owns about half the gas rights under its parks, has a law that prohibits their disturbance by natural-gas drilling.

New York officials have proposed a similar measure.

"I think Pennsylvania deserves no less," Quigley said.

The state is unclear about the amount of park acreage for which it owns mineral rights. Quigley said determining that would require a prohibitively expensive title search.

But PennFuture identified some of the most popular parks as being at the greatest and most immediate risk.

They include:

Ohiopyle, a white-water rafting destination.

Pymatuning, the only known place in Pennsylvania where bald eagles have nested continuously.

Cook Forest, famous for its old-growth forest.

Rickets Glen, home to 94-foot Canoga Falls.

Goddard, which has a large waterfowl habitat.

Yellow Creek, an important lake for migrating birds.

A spokeswoman said drillers and others in the industry have expressed interest in each.

Quigley said drilling could damage not only the parks, but also the income they generate. State parks return $10 to local economies for every dollar of state investment, he said, generating more than $818 million in local sales and more than 10,500 jobs.

Contact staff writer Sandy Bauers at 215-854-5147, sbauers@phillynews.com, or @sbauers on Twitter.