After years of effort, Petaluma residents working to save an 11-acre parcel of land on the city's western edge from development have reached an agreement to buy and preserve the land as open space.

The grassy land, on Paula Lane at Sunset Drive, officially will become the Paula Lane Open Space Preserve once the formal agreements are signed later this year.

But last month, a major hurdle was overcome: an agreement on a purchase price with the owners, two sisters who live in San Leandro.

"The good guys won," said Paul Selinger, a retired sculptor, artist and writer who served as the original president of the nonprofit Paula Lane Action Network. "I'm thrilled. We stuck it out and we won."

The $1 million deal must be approved by the Sonoma County Open Space District, which agreed to put up that amount if the nonprofit agreed to manage the property and maintain educational programs.

The city of Petaluma will own the land, which will remain undeveloped under a conservation easement.

Beginning in 2001, neighbors in the Paula Lane and Sunset Drive area banded together to try to keep the land from being developed into a residential subdivision. The owners eventually abandoned that effort.

In 2008, Petaluma applied for a $1 million grant from the county open space district on behalf of the Paula Lane group. Price negotiations for the property continued without an agreement until now.

"Given the market, it hasn't been so great to get property deals done," said Scott Brodhun, Petaluma's assistant city manager who coordinated the effort with the county district. "There was a time where when I didn't think we would."

According to the Paula Lane group, the acreage to be preserved is part of what's left of a farm settled in about 1897 by the John Pauli family, after whom the street is named.

The land was farmed until the 1960s. Since then, the open fields have become a thriving wildlife habitat.

As part of the nonprofit groups commitment, its volunteers will provide educational programs in sustainable agriculture, habitat restoration and a community garden. Public trails for wildlife viewing and on-site caretakers are also planned.

The land is important, Selinger said, because it is a transition from the city to the countryside. It includes clusters of trees, open grasslands and wetland areas.

"This is an aesthetically special place," he said. "It's a wonderful, beautiful site that looks to the west from the edge of town. It calls you back."