It's not a new idea, but it's getting a big, new push.

The Western Virginia Land Trust Board of Trustees voted this week to ask Roanoke to put conservation easements on most of Mill Mountain and all of the Carvins Cove Natural Reserve. The easements would cover more than 13,500 acres -- more than three times the size of the state's largest conservation easement.

Land Trust Executive Director Roger Holnback said that Roanoke County, the Western Virginia Water Authority and other local public entities also have resources that should be protected with easements in the near future.

"We're starting with the city of Roanoke because of the current debate over the future of Mill Mountain," Holnback said. "We're hoping that the city can accomplish something that will serve as a model for the rest of the region."

Conservation easements are negotiated agreements that permanently restrict development and land use. Roanoke City Council has already approved plans that call for easements on the mountain and the cove.

The land trust board wants the council to follow through.

"We just feel like a conservation easement on Carvins Cove and the face of Mill Mountain is a no-brainer," Holnback said.

It could be part of the city's re-branding, Holnback said. "It could get us out there as one of the cool green cities to live in."

Valley Forward, an organization of young professionals, proposed an upscale inn and restaurant on top of Mill Mountain earlier this year -- a proposal that prompted substantial public debate. That proposal may be at odds with an easement. Valley Forward Chairman John Lugar couldn't be reached for comment Friday afternoon.

Arguing that there's no inherent conflict between conservation and economic development, Holnback said, "We're not about confrontation and taking sides. We're really trying to find that common ground that's supportive of both agendas. We are really trying to find the win-win in this."

The land trust proposal would leave 15 acres at the top of the mountain out of the easement.

"We acknowledge that the top of Mill Mountain is a built environment,' Holnback said.

That section holds the Mill Mountain Zoo, the Discovery Center, parking lots, picnic shelters, a broadcasting tower and the 88 ¹₂-foot-tall Mill Mountain Star. But the city's management plan for the mountain recommends that future construction in that area rise no higher than the treetops. The land trust resolution endorses that idea.

Junius Fishburn gave the city 574 acres on and around the mountain in 1941 on the condition that it be used as a park. More than one Roanoke city attorney has said that any plan that seems to deviate from that condition must be approved by Fishburn's heirs.

Louise Kegley, Fishburn's granddaughter, said she thinks her family will support the easement proposal.

"We're just tired of every two or three years somebody coming to us and saying, 'What do y'all think of this?' " she said.

There have been at least a dozen proposals for development on the mountain -- hotels, restaurants, a theater, a ski slope, a sculpture garden, an amphitheater and an art museum -- since 1965.

The land trust has conducted a low-key campaign for the conservation easements for years. The latest push, though, is going to be more visible.

Roanoke City Councilwoman Gwen Mason resigned from the land trust board recently because she knew the organization was about to become much more active in its lobbying of the city council.

Like Holnback, Mason believes it's a myth that conservation and green space are at odds with economic development. They go hand in hand, she said.

"Great cities have great green spaces," Mason said. London has Hyde Park, she said. New York City has Central Park. "You can't have economic development without a green city and a clean city and a beautiful city."

Although Mill Mountain is more visible, an easement at Carvins Cove might be more significant and likely less controversial. It is already a nature reserve, and a piece of one of the best known scenic features in America -- the Appalachian Trail -- crosses a ridge above the cove's reservoir. which is part of the Roanoke Valley's water system. A conservation easement on its 13,000 acres of reservoir, ridges and trails would be more than three times the size of the state's largest.

Gov. Tim Kaine has made it his administration's goal to preserve 400,000 acres from development by 2010. The state protected a record 95,000 acres last year, so it must preserve more than 101,000 acres for each of the final three years of Kaine's term to meet the governor's goal.