For three years, open space advocates have feverishly negotiated to prevent thousands of acres of forest and farmland in eastern Wake County from becoming another subdivision.

But their biggest breakthrough came this month, when residential developer Greg Ferguson agreed to preserve 160 acres of prime real estate near Lake Myra, a historic fishing hole a few miles southwest of Wendell.

For Ferguson, it's not just a goodwill gesture.

He's building a massive 4,000-home subdivision just northeast of Lake Myra called Wendell Falls. He said he thinks nearby open space will make his homes more valuable in the long run.

"It's the right thing to do from a conservation standpoint," he said, "and it's a terrific selling point for the neighborhood."

Traditionally, conservationists and home builders have faced off over wide-open spaces. When a national advocacy group called Marks Creek a "threatened" landscape in 2003, home builders were the unspoken bad guys.

But some on both sides say it doesn't have to be that way.

Kevin Brice, executive director of the nonprofit Triangle Land Conservancy, praised the Marks Creek deal and a similar agreement in the new Treyburn subdivision in north Durham, which preserved 240 acres.

"We are better allies than we are competitors," he said.

The land, which Ferguson sold to the county for $3.2 million, includes access to the lake. County planners said it is the heart of the Marks Creek watershed, marking a major milestone in their efforts to protect the area.

"This gives us the emerald," open space advocate Sig Hutchinson said.

The watershed, which serves Johnston County, is a top concern for local conservationists. In 2004, the county set the goal of protecting 4,417 acres there for what it hopes will be the eastern Wake equivalent of Umstead State Park, which is near Cary.

But the area is also a prime spot for developers.

Last year, the US. 64/264 Knightdale Bypass opened a few miles away, making the rural farmland just a short commute from downtown Raleigh. The city recently took over Wendell's water supply, making future growth even easier.

With the Lake Myra land, the county has preserved just 737 acres, roughly a sixth of what it hopes to save.

Lawrence Mattox, 54, grew up on a family farm near Marks Creek. The county sent him a letter a few years ago about its interest in preserving the 238-acre property, but he mostly forgot about it.

In February, he sold it to Ferguson, who needed it to build a sewer line for Wendell Falls. He said the land, tilled by his grandparents, was no longer profitable because of changes in the tobacco industry.

"It just turned out to be the right time to sell," he said.

The town of Wendell required Ferguson set aside at least 73 acres of open space before it would approve his subdivision. In many cases, developers choose wetlands and hills where homes couldn't be built anyway.

Instead, Ferguson chose to set aside 20 acres for outdoor recreation and 65 acres of stream buffers and nature trails. The 160 acres he sold the county, part of the Mattox farm, could have been used for expensive lakefront homes.

It was more than Ferguson needed to do, but he said he wanted to take the extra step. That has helped prevent the kind of protests from neighbors that hurt a proposed development north of Wendell called Rockbridge two years ago.

County commissioners at first turned down that subdivision because it would have used a controversial lagoon-and-spray wastewater treatment system. They approved a later plan that stuck with conventional methods.

But Ferguson said he learned his lesson. He studied the problems that developers have run into in recent years and tried to make sure that Wendell Falls would not face them as well. That included preserving open space.

When commissioners approved the purchase at their December meeting, Ferguson joked about how much better the proposal was received than Rockbridge.

"Any time I can get up here and speak without 200 people in red shirts here to oppose me is a good thing," he said.