Conservation groups are cautiously celebrating a decision to suspend planning for the Mid-Atlantic Power Pathway, a high-voltage transmission line that would have moved electricity between northern Virginia and the Delmarva Peninsula.

Pepco Holdings Inc. proposed the Mid-Atlantic Power Pathway in 2006 at a projected cost of $1.2 billion. The 152-mile long transmission line would have carved a path across the floor of the Chesapeake Bay, impacted several of its tributaries, and changed rural viewsheds on the Eastern Shore, including areas along the Captain John Smith Chesapeake National Historic Trail.

The line would also have required a permit for the largest permanent impact to nontidal wetlands ever allowed in Maryland. The work would have affected two of Maryland's healthiest watersheds, Mattawoman Creek and Parkers Creek.

PJM Interconnection, which manages the power grid for a 19-state region, originally approved plans for MAPP. In August, PJM suspended the project because an updated analysis showed that it is not needed to stabilize the power grid.

But uncertainties about future power generation led PJM to suspend the project rather than cancel it completely.

PJM has advised transmission owners to "continue with efforts necessary to allow the MAPP project to be quickly restarted should planning activities determine the need for it."

PHI has already purchased most of the Eastern Shore land needed for the power line and has applied for a wetlands permit with the Maryland Department of the Environment.

The permit application is still on file, but PHI spokesman Matthew Likovitch said in a written statement that "We are discontinuing any planning for MAPP and are reviewing the actions necessary to properly close out the project."

Likovitch said PHI is disappointed by the decision. "MAPP would have enhanced electric system reliability in the mid-Atlantic region. It would have supported offshore wind power and other renewable energy sources, as well as new gas-fired power plants," Likovitch wrote. "The project also would have provided an economic boost to communities along its route with tax revenue and construction jobs."

The Mattawoman Watershed Society, Eastern Shore Land Conservancy and Dorchester Citizens for Safe Energy were among those who criticized MAPP, questioning the need for the project and the pace at which it moved.

"I'm relieved. But relief in this case is a temporary word. I'd like to see it dead," said Bonnie Bick of the Mattawoman Watershed Society.

Even as MAPP is put on hold, opponents remain critical of the process that moved the project forward.

The Eastern Shore Land Conservancy took note of MAPP because its path could potentially affect protected lands. "But as we dug into the issue, we became concerned about the lack of authentic public engagement and opportunities for influence. It felt a lot like David versus Goliath," said deputy director Amy Owsley.

Owsley said she hopes the experience will spark a broader conversation about the role of energy for the Eastern Shore. "We are quite excited that the MAPP line is no longer, and we are also excited about what it could mean for the region moving forward," she said. "It's an opportunity for the Eastern Shore and the Delmarva Peninsula to take a hard look at energy as an economic driver."

Richard Klein of Community Defense and Environmental Defense Services said that Maryland lacks an effective long-term planning process for energy and that hard questions from concerned citizens were critical for slowing MAPP down.

"Otherwise, permitting could have gotten to a point that MAPP would have been under construction. We would have had an incomplete project with lots of expense and zero benefits," Klein said. "What we really need is for the state to adopt a process with a long-range view of energy needs steering new projects in a direction that is best for everybody."

In the Mattawoman watershed, Bick looks forward to setting MAPP aside to focus on other tasks. She is promoting a report published this spring, in which state and federal agencies point to the importance of the Mattawoman watershed and recommend ways to protect it.

"The Mattawoman has absorbed too many impacts to date and what we need to do now is come up with a restoration and protection plan. It would not include MAPP," Bick said.