Top National Park Service officials again have found themselves sued by conservation groups over one of their permitting decisions, this time in response to a decision to allow the expansion of a transmission corridor through the Delaware Water Gap National Recreation Area and two other units of the park system.

The lawsuit was not unexpected, as the Park Service early this year was criticized for its intent to approve the project.

Pennsylvania Power and Light Electric Utilities and Public Service Electric and Gas Company have wanted to replace an existing 230kV transmission line through park lands with a double circuit transmission line carrying a new 500kV line.

According to the Park Service, the Susquehanna-Roseland power line proposal includes the replacement of an existing transmission line with an approximately 145-mile long 500 kV transmission line from the Susquehanna Substation in Pennsylvania to the Roseland Substation in New Jersey, and several 500 – 230 kV substations in both Pennsylvania and New Jersey. Fewer than five miles involve Park Service lands.

In March the Park Service, after reviewing agency and public comments made during a 60-day comment period, came down in favor of that request.

“In identifying the preferred alternative, we closely examined the existing easements owned by the utilities, the impacts of the proposed transmission line, alternatives to the proposal, and mitigation measures to avoid and minimize adverse impacts to park resources,” Dennis Reidenback, the Park Service's Northeast regional director, said at the time.

But on Monday a coalition of national, regional, and local conservation groups in New Jersey and Pennsylvania filed suit in federal court challenging that decision, which was formalized on Oct. 1. The groups maintain that allowing the power line through the Water Gap and across the Appalachian National Scenic Trail and the Middle Delaware National Scenic River is at odds with the Park Service's governing mandate to protect parks and to prevent impairment to park resources.

“This decision by the Park Service will permanently scar the landscape and degrade the visitor experience in some of the most visited national parks in the country,” said Hannah Chang, an attorney with the public interest environmental law firm Earthjustice that, along with the Eastern Environmental Law Center, filed the lawsuit on behalf of the groups.

“And what’s worse, the damage from constructing and operating this 500-kV electric transmission line on nearly 200-foot-tall towers through these treasured places is unnecessary," she added in a release. "Serious questions have been raised about the need for this project.”

Several conservation groups have questioned the need for the transmission line in a pending appeal of the New Jersey Board of Public Utilities’ approval of the project.

The new transmission line will largely follow the route of an existing 85-year-old power line, but the new towers will rise more than twice as high as the existing towers and would include clearing substantially more trees and the construction of access roads through the parks, the groups said.

“The NPS decision is extraordinarily disappointing. It clearly violates the founding law of national parks, which requires the agency to 'conserve the scenery' and protect park resources from impairment,” said Cinda Waldbuesser, Pennsylvania senior program manager for the National Parks Conservation Association. “America’s national parks are special places, set aside for inspiration and recreation, and are not blank spots on the map, conveniently set aside for development projects like super-sized transmission lines.”

At the Appalachian Mountain Club, Mark Zakutansky said that group "worked to save this unique natural area from the Tocks Island Dam project over 40 years ago. Our volunteers have invested over 50,000 hours building and maintaining trails there, and each year we introduce over 10,000 people to the area through outdoor programs. Millions of people from New York City and Philadelphia find respite in the area’s magnificent views and recreational opportunities. We cannot stand on the sidelines while the Delaware Water Gap is permanently despoiled and we will fight once again to protect it.”

The lawsuit focuses on the National Park Service Organic Act and the Wild and Scenic Rivers Act, saying the approved transmission project is in violation of both those acts. The groups also point to deficiencies in the agency’s required environmental analysis under the National Environmental Policy Act.

“We continue to be concerned that the impacts to the scenic values of these national treasures have not been adequately addressed during the environmental review process,” said Mark Wenger, executive director for the Appalachian Trail Conservancy.

The coalition wants the court to overturn the NPS decision and stop construction of the project until the NPS complies with federal law.

According to the conservationists, the "4.3 miles of the transmission line that runs through national park lands crosses unique and sensitive resources. In a July 2012 environmental impact study conducted for the NPS, the human use and ecological impacts from the project were estimated at $89 million."

As announced in the Park Service’s October 1 Record of Decision, the utilities have agreed to pay $56 million in return for damaging the parks. "This compensatory mitigation and its underlying methodology and rationale were never previously disclosed or explained by the Park Service during the environmental review process," the groups maintained.

"You cannot mitigate for the degradation of a national park or a portion of the Appalachian Trail,” said Marc Ross, executive director of Rock the Earth.

The Delaware Water Gap National Recreation Area, the Delaware River that flows through it, and the famed Appalachian Trail that traverses its ridges attract more than 5.2 million visitors a year who want to enjoy the recreational opportunities of the Delaware’s clean, free-flowing waters and the park’s spellbinding waterfalls and diverse wildlife that include bald eagles, peregrine falcons, and black bears. The National Recreation Area was named a Top 10 most-photogenic national park nationwide for fall foliage. The Delaware River is the last free-flowing river east of the Mississippi. The Appalachian Trail, completed 75 years ago and designated as the nation’s first national scenic trail in 1968, is enjoyed by nearly three million people each year. Together, these national parks offer the very best outdoor recreational opportunities for those living in the mid-Atlantic region.

“Trail Conference volunteers built the Appalachian Trail along the Kittatinny ridgeline to take advantage of the glorious views,” said Ed Goodell of New York–New Jersey Trail Conference. “Now, 50 or more transmission towers will blight the viewpoints along 20 miles of Appalachian Trail.”

“We have no recourse but to take this issue to the courts. We will fight for the integrity of our parks even if the National Park Service won't,” said Jeff Tittel, director of the New Jersey Sierra Club. “What’s at stake is the protection of valuable public lands cherished by millions of outdoor enthusiasts and nature lovers. If they can do this here, what’s next – the Everglades, Yosemite, Yellowstone?”

The lawsuit was filed by Earthjustice and Eastern Environmental Law Center on behalf of the Appalachian Mountain Club, Appalachian Trail Conservancy, Association of New Jersey Environmental Commissions, Delaware Riverkeeper Network, New Jersey Highlands Coalition, New York–New Jersey Trail Conference, National Parks Conservation Association, Rock the Earth, Sierra Club, and Stop the Lines.