An area of hills and valleys southwest of Sebastopol could become a federally recognized winegrowing region for cool-climate chardonnay and pinot noir. A petition for more than 16 square miles of land was recently submitted to the Alcohol and Tobacco Tax and Trade Bureau. If approved, the region would be known as the Sebastopol Hills American Viticultural Area. It would join the larger North Coast Winegrowing Region. Sonoma County already has 18 federally-approved winegrowing areas.