Clearing the way for a landmark Sonoma County conservation deal, the state Coastal Conservancy board Thursday approved a $10 million contribution toward the purchase of Preservation Ranch, a 19,652-acre property that sprawls across the county’s northwest corner.

A national conservation group has reached an agreement to buy nearly 20,000 acres of timberland in northwestern Sonoma County, a move that derails the long-disputed, forest-to-vineyards conversion project pushed by CalPERS, the giant state workers pension fund.

The city of Sonoma appears on the verge of acquiring a 98-acre hillside parcel that promises to open up sweeping vistas of the city to the public. But dog owners, long concerned with the transfer of the Montini Preserve to the city, say the latest terms of the deal still exclude them from bringing their pets on the property.