A county ordinance that binds new vineyards to best management practices to minimize erosion and sedimentation has proven effective, county officials say. Stacy Carlsen, director of Agriculture, Weights and Measures, told the Board of Supervisors on Tuesday that the Vineyard Erosion and Sediment Control Ordinance, adopted in 2011, has been a valuable asset in protecting land and stream habitats at the only vineyard that currently abides by the practices. Since the program came into effect, the county has received only one application to develop a vineyard: a five-acre plot on George Lucas’s Skywalker Ranch in Nicasio, which already had 10 acres. (The ordinance does not apply to vineyards planted prior to 2011.) Tom Johnson, spokesperson for Skywalker Vineyards, said the plot, planted in 2015, was an extension of an existing chardonnay vineyard on the ranch. Preventative measures for erosion, such as planting with straw mulch and installing drain catch basins and jute netting fiber rolls, have safeguarded the nearby Halleck Creek. “The test was last year’s heavy rain season to determine the effectiveness of the program, and it worked quite well,” Mr. Carlsen said. Marin has approximately 182 acres of vineyards—a far cry from Sonoma County’s roughly 62,000 acres. Stefan Parnay, deputy director of Agriculture, Weights and Measures, told the board that this is due to wind and fog conditions that can obstruct the growth of grapes, as well as a scarcity of water. Mr. Carlsen added that the ordinance was put into place as a precautionary measure in case there’s any rapid development of vineyards in Marin, though Mr. Carlsen is skeptical that such a run will occur. “The return on investment might be better suited if you planted strawberries or artichokes,” he said.