The first plan to manage roughly 250 miles of road and trails in Marin’s open space preserves, and its environmental impact report, were approved by county supervisors on Tuesday after years of local input and pushback on restrictions in earlier iterations. Supervisors made a few final tweaks to the plan this week, including allowing dogs to remain off-leash in the Gary Giacomini Preserve in the San Geronimo Valley and requiring monitoring when the open space district experiments with new kinds of trail use, such as alternate days for bikers and equestrians. The creation of the plan, which will regulate 34 preserves, has been a long process: four years and 15 public meetings in the making. The county open space land is comprised largely of acreage inherited from private owners, with fire roads and trails in poor shape. The plan approved this week is the first document to comprehensively guide their management. An initial draft and accompanying environmental impact report released last year spurred so much opposition that county staffers devised major revisions and recirculated the environmental document. The outcry came from different interest groups, most notably mountain bikers who wanted more opportunities and felt their speedy recreation was unfairly cast as a danger to hikers and equestrians. But other groups were critical of initial plans to require the decommissioning of trails, and hikers opposed language suggesting they would not be allowed to venture off-trail. Revisions addressed the concerns, and also included a system to evaluate new or modified trails based on a ream of biological and physical impacts. Each trail project will receive a score indicating whether it increases or reduces environmental impacts; every year, the open space district will only approve a package of trail plans if the total provides a net environmental benefit. Mountain bikers who spoke at the meeting this week were largely happy with the plan, though a few equestrians continued to criticize bikers for scaring other recreators. (Supervisor Kate Sears applauded the crowd, mostly bikers, for remaining so civil that afternoon.) Dog walkers in the valley who made pleas at Tuesday’s meeting about the leash restriction in the Giacomini preserve—which they said was virtually the only local place to walk dogs off leash—were surely pleased that they can continue to walk their dogs under voice control. And Linda Dahl, the general manager of the parks department, was ready for the planning process to finally end. “If you asked me if these [documents] were perfect or if I would never change a thing, the answer would be of course not. I have a high tolerance for process—I’m a lifelong planner—and even I am ready to move on.”