The state has bought the development rights to 98 acres in the Piney Run Rural Legacy area for $328,300, an action that will safeguard farmland in northwestern Baltimore County,

The purchase of a conservation easement on the Davidson land allows the third-generation farmers who own the property to continue working their family's land, but prohibits them from building on it.

Jack Dillon, executive director of the Valleys Planning Council, a private land-preservation group that worked on the acquisition, said preservationists sought the easement to create a swath of farmland protected from development in the area.

"It's going to fill in a nice hole there," Dillon said. "We're trying to build a block of contiguous land. There are still some [parcels] left, but this is a key one."

County Councilman T. Bryan McIntire, a north county Republican, said placing a conservation easement on the Davidson property means 600 contiguous acres in the area are protected from development.

Grain and pumpkins are grown on the land. The state Board of Public Works approved the purchase Dec. 18. The acquisition raises the amount of protected land in the Piney Run Rural Legacy area to more than 3,000 acres. The effort has cost the state $10.9 million.

The Land Preservation Trust and Maryland Agricultural Land Preservation Foundation will hold the easement.

The easement also requires the installation of buffers along streams running through the property, thereby preventing livestock from contaminating water that feeds the Loch Raven Reservoir, which supplies drinking water to the Baltimore area.

"This easement will help to preserve the region's rich agricultural heritage by keeping another family farm in business," Gov. Parris N. Glendening said in a statement. "At the same time, we will ensure that Baltimore's water supply and the region's streams and rivers remain clean, safe and healthy."

The nearly 20,000-acre Piney Run Rural Legacy area is largely undeveloped farmland. The area includes the communities of Upperco, Butler, Armacost and Trenton.

The county has 55,000 acres of land in five Rural Legacy areas, which were designated under a Maryland program encouraging the preservation of large blocks of land with endangered species, farmland, forests, historic villages and battlefields.