MARIN COUNTY, Calif.— The Marin County Board of Supervisors unanimously approved a conservation ordinance on Tuesday that would protect coho salmon habitat and end a 15-year legal battle over California’s most important watershed for the endangered species.

The Stream Conservation Area Ordinance would set development limits and improve riparian habitat and water quality for Central Coast coho and steelhead populations in the San Geronimo Valley and Lagunitas Watershed.

The Center for Biological Diversity and the Salmon Protection and Watershed Network had sued the county for failing to adopt conservation measures that were deemed necessary under its own environmental analysis.

“It’s about time the endangered coho salmon get the protection to survive a warming planet,” said Peter J. Broderick, a senior attorney at the Center. “I’m relieved that after many years of litigation, the county has finally agreed to do the right thing and adopt these common-sense measures before it’s too late.”

Legal challenges from the conservation organizations resulted in a string of losses for the county.

In April a Marin County Superior Court judge ruled the county violated state environmental law by failing to mitigate the cumulative impacts to coho and steelhead from streamside development in the watershed, which were allowed under the 2007 Countywide Plan.

“We stood our ground and are delighted that we finally have science-based regulations that will give the endangered coho salmon a fighting chance at survival in Marin,” said Todd Steiner, an ecologist and executive director of SPAWN. “This population is critical to the survival of the species throughout Central California.”

Development and habitat loss are the primary threats to the dwindling salmon populations, which are protected under the federal Endangered Species Act and the California Endangered Species Act. The San Geronimo Valley is home to approximately half of the entire Lagunitas Watershed coho population, one of the largest Central Coast coho populations remaining in California.

The new ordinance will ensure there will be “no net loss of habitat” in the last undammed headwaters of the Lagunitas Watershed, which runs through state and national park lands before emptying to the Pacific Ocean in Tomales Bay.

The Center and SPAWN are represented by attorneys at the Stanford Law School Environmental Law Clinic and the Law Offices of Michael W. Graf.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

The Salmon Protection and Watershed Network, or SPAWN, is a program of the global ocean conservation nonprofit Turtle Island Restoration Network that protects endangered marine species around the world.