A pending settlement of a federal lawsuit challenging oil and gas development in the Allegheny National Forest will allow drilling of 588 wells this year but delay all other new wells until a forestwide environmental impact study is completed next April.

The agreement between the U.S. Forest Service and three environmental groups that filed suit last November requires the service to conduct an environmental impact review of each new well proposed after the group of 588 and give the public a chance to review and comment on all drilling proposals.

It also stipulates that no drilling can occur in the Allegheny's Wilderness Study Areas, National Recreation Areas, Inventoried Roadless Areas, Tionesta Scenic and Natural Areas and the Morrison Run Area near the Rimrock Overlook unless an environmental analysis is done.

It will postpone action for a year on pending applications to drill approximately 440 oil and gas wells in the forest, about 100 miles northeast of Pittsburgh.

"With this settlement the Forest Service is making a commitment to disclose to people living near the Allegheny National Forest what impact oil and gas drilling will have on water quality, recreational opportunities and the other benefits they expect from the national forest in their back yard," said Andy Stahl, executive director of Forest Service Employees for Environmental Ethics.

The settlement reached recently by the Forest Service Employees for Environmental Ethics, the Allegheny Defense Project and the Sierra Club requires approval by U.S. District Court, but the Forest Service already is working on implementing it.

Kathy Mohney, a Forest Service spokeswoman, said three public meetings will be held to publicize the terms, and the service will publish a notice in the June 1 Federal Register of its intent to conduct the forestwide environmental review.

A round of public hearings to solicit comments on the environmental review and drilling alternatives will be held on June 2, 3 and 4 in communities surrounding the 513,000-acre forest in Elk, Forest, McKean and Warren counties. The Forest Service schedule calls for publishing a draft environmental review in January 2010 and a final document that April.

"We hope to get a team in place soon to begin working on the assessment of the environmental, social and economic effects of oil and gas well development in the forest," Ms. Mohney said. "We'll also be asking oil and gas companies to submit what they want to do in the forest in the next three years because there will be new wells proposed and there will be a process if we have to continue to do [National Environmental Policy Act] reviews of all future applications."

Well drilling in the forest, where the surface rights are owned by the federal government but 93 percent of the underlying mineral rights remain in private hands, has been booming in recent years as oil and gas prices have risen.

Last year, 984 new wells were drilled and 1,300 in 2007. Since 2005, 3,700 new wells have been drilled and at least 12,000 are operating in Pennsylvania's only national forest.

Environmental groups have said that's too many because of the cumulative impact of the drilling on streams and groundwater, forest fragmentation, erosion and endangered and threatened wildlife populations like the northern flying squirrel and the timber rattlesnake.

Ryan Talbot, Allegheny Defense Project forest watch coordinator, said the settlement acknowledges the Forest Service's legal authority to establish reasonable conditions and mitigation measures to prevent drilling damage and protect surface resources.

"This important acknowledgment signals a new direction for regulating oil and gas drilling on the Allegheny that will better protect water and air quality, wildlife habitat and recreation opportunities."

The Forest Service has not granted a "notice to proceed" for any new well in the forest since Jan. 16, when its regional office in Milwaukee took over the local well review process. Because of the settlement, Allegheny National Forest officials will resume those duties immediately, Ms. Mohney said, and expect to issue the first of the 588 notices to proceed with new well drilling within two weeks.