10/13/2014 04:41 pm ET Updated Dec 13, 2014

Obama's Lucky Thirteenth

Lee Pettet via Getty Images

California may be famous for its beaches, but what really defines the state's geography are its many mountain ranges (and I'm not just saying that because the Sierra Club took its name from one of them). Last Friday, President Obama permanently protected one of those mountain ranges -- the San Gabriels that bound Los Angeles to the north and east -- by designating almost 350,000 acres of the Angeles National Forest as our newest national monument.

At a time when the U.S. Congress has all but abdicated responsibility for protecting public lands, designations like this one are crucial to protecting treasured landscapes before it's too late. Although it's his thirteenth monument designation, the San Gabriel Mountains National Monument is only President Obama's third designation of an extensive natural landscape. The previous two were Rio Grande del Norte and Organ Mountains-Desert Peaks National Monuments, both in New Mexico. (At 490,000 square miles, last week's much-needed expansion of the Pacific Remote Islands Marine National Monument is by far Obama's biggest designation, but you can't really call it a landscape.)

But the San Gabriel Mountains National Monument stands out for another reason: These magnificent mountains rise above one of the most diverse metropolitan areas in the United States (and the second most populous). That means they can provide much-needed natural open space and outdoor recreation opportunities for Angelenos and other Southern Californians. The Sierra Club was founded on the principle that people can benefit from getting closer to nature. Sometimes, that means bringing nature closer to the people -- in this case, at least 15 million people, who live less than 90 minutes away.

Although the Antiquities Act has given presidents the authority to make national monument declarations since 1906, the real power to save landscapes like the San Gabriels comes not from the White House but from locally based grassroots campaigns. In this case, San Gabriel Mountains Forever (a coalition that includes the Sierra Club) devoted years to building community support, including public meetings, thousands of public comments, letters, and postcards. Last week, all that work paid off.

But our work isn't finished yet. We still have important, critically endangered public lands, such as the Grand Canyon Watershed and Greater Canyonlands that deserve permanent protection, and those of us who love wild places won't rest until that happens. Today, though, let's take a moment to congratulate the people of Los Angeles on their brand new national monument and thank President Obama for making it official.