A deal more than a decade in the making to save an 11-acre parcel on the western edge of Petaluma got formal approval Tuesday at the Sonoma County Board of Supervisors.

The board authorized granting $1.05 million in county open space funds to the city of Petaluma to support its purchase of the former farmland on Paula Lane and Sunset Drive, site of the long-planned Paula Lane Open Space Preserve.

The move was cheered by those who fought off a proposed 21-home subdivision on the land years ago. Since then they have worked with the city and county open space district to find a way to buy it.

The grassland parcel is home to rare wildlife species, including the American badger, as well various raptor and bird species. Plans call for a public trail, environmental education and sustainable farming programs.

The purchase could close next month and guided public access could begin this summer, with rollout of regular access and the rest of the plans set for the next three years.

"We're looking forward to finally being able to implement the project," said Susan Kirks, chairwoman of the Paula Lane Action Network, the nonprofit behind the campaign to protect the property.

A deal struck last fall with the owners, two sisters who live in San Leandro, paved the way for the purchase.

The Paula Lane Action Network is responsible for opening and operating the preserve. It has pledged about $1.1 million in services, materials and activities toward the effort.

The city of Petaluma will own the land and hold a conservation easement on it to ensure it remains undeveloped.

The city has pledged $790,000 toward its role of oversight and ownership. The funds are set to come from rental income of two homes on the property — about $21,000 a year — plus staff time and other grants.

The 11-acre property sits just outside the city limits, but within the urban growth boundary. It is the remainder of a 33-acre farm settled in the late 1890s by the John Pauli family, after whom the street is named, according to the Paula Lane Action Network.

The land was farmed until the 1960s. Since then, the open fields have been reclaimed by wildlife and served as a de-facto greenbelt on Petaluma's western edge. Supporters touted the preserve as another protected link in the swath of undeveloped land that includes nearby Helen Putnam Regional Park, just to the south.

The wildlife species that use that corridor "will have their habitat forever," Kirks said.