The Sonoma County Board of Supervisors on Tuesday unanimously approved an emergency halt to new vineyards and orchards on forested slopes and hilltops.
The four-month freeze was prompted by a wave of new vineyard projects and a need to update 12-year-old farming regulations that don't deal with tree removal, officials said.
County Agricultural Commissioner Tony Linegar called that loophole a "deficiency" in the current rules.
"We've seen proposals that would remove a significant number of trees on steep slopes. I don't think it takes a rocket scientist to know that that is going to affect erosion," said Linegar, who assumed his post last month.
Grape growers and agriculture leaders provided guarded support for the move, with some saying they recognized the need to revise rules implemented in 2000. Those regulations allow development of hillside vineyards on slopes up to 50 percent, but contain no restrictions on tree removal.
"We understand that even the best rules over time need adjustment," said John Holdredge, board president of the Russian River Valley Winegrowers.
Still, many wine industry representatives voiced concern over the possibility of tighter regulations, saying they could impact the local economy and be a blow to smaller vineyard operations.
"I ask the process to be cognizant of that specific issue," said Pete Opatz, vice president of Napa-based Silverado Premium Properties, which manages more than 5,000 acres of grapes in the region and vineyards on the Central Coast.
Environmentalists and others who have questioned the reach of vineyards into previously untilled country welcomed the move.
"I've watched the cumulative impact of ridgelines that are stripped of trees and (replaced) by vineyards," said Bonnie Berkeley, who lives above Dry Creek Valley.