A 90-day public comment period opened this week for a proposed rule in the Golden Gate National Recreation Area’s Dog Management Plan that would ban off-leash dog walking everywhere on national parklands in Marin County except for Rodeo Beach, at the county’s southernmost end. Currently, dogs are allowed off-leash at Rodeo Beach, Muir Beach, Oakwood Valley Road in Mill Valley, Homestead Valley in Mill Valley and Alta Avenue in Marin City. Park officials extended the original 60-day comment period at the request of Congresswoman Nancy Pelosi. The change would not apply to trails and beaches in the Point Reyes National Seashore, where no off-leash dog walking is allowed. (Dogs presently are not allowed on or off-leash at Stinson Beach’s park-managed section of beach.) The proposed rule would also limit permitted professional dog walkers to no more than six dogs at a time and would give the park superintendent discretion to designate new trails as on-leash, off-leash or dog-prohibited for new trails added to the system in the future. A process 14 years in the making, the new rule is set to take effect next year. But dog advocates are up-in-arms, calling the change a major blow to public access. “The proposed rule for the Dog Management Plan represents the single biggest loss of public access to the G.G.N.R.A. since its inception,” said Laura Pandapas, of Muir Beach. “And the National Park Service has failed, despite thousands of pages of Environmental Impact Statements and millions of taxpayer dollars, to give any solid, substantive reasons or data to support taking away so much access for people with dogs.” Ms. Pandapas argued that restricting dogs to leashes at Muir Beach represented an indirect ban on dog walking there, given that dogs would not be able to roam freely and exercise—the main purpose of dog walking. But park spokesperson Howard Levitt disagreed. “I wouldn’t say on-leash dog walking is a ban on dogs,” he said. “It’s a small beach, and it does have naturally sensitive areas in the lagoon, as well as the riparian areas at Redwood Creek.” Mr. Levitt said the plan strikes a balance between recreational access and environmental preservation. “Our job is to accommodate a wide spectrum of visitor experiences, as well as preserving natural resources,” he said. “And actually, we view dog walking as a healthy and appropriate and enjoyable way of visiting the park, if it’s well-managed.” Comments may be submitted by mail to Fort Mason, Building 201, San Francisco, CA 94123, or online at www.federalregister.gov/articles/2016/02/24/2016-03731/special-regulations-areas-of-the-national-park-service-golden-gate-national-recreation-area-dog.