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San Gabriel Mountains National Monument

A photo of West Fork Ranger Station On Oct. 10, 2014, President Barack Obama designated 346,177 acres of existing federal lands as the San Gabriel Mountains National Monument, the eighth national monument under Forest Service management.

The recently designated national monument covers 342,177 acres of the Angeles National Forest and 4,002 acres of neighboring San Bernardino National Forest. The area is within 90 minutes of 15 million people in the Los Angeles Basin.

The designation will help ensure these lands remain a benefit for all Americans through rock art that provides a glimpse into ancient civilizations, an observatory that brought the world the cosmos, and thousands of miles of streams, hiking trails and other outdoor recreation opportunities.

Soaring high above the Los Angeles Basin, the San Gabriel Mountains also are working lands that provide Angeleños 70 percent of their available open space and 30 percent of their drinking water. The monument serves as the backyard to the nation’s second-largest urban center.

Monument highlights include:


The San Gabriel Mountains contains some of the greatest biodiversity in the country, including four wilderness areas – Magic Mountain, Pleasant View Ridge, San Gabriel, and Sheep Mountain – and unique geological features such as the San Andreas Fault. Other highlights are:

  • The rivers of the San Gabriel Mountains not only provide drinking water but are vital in the support of native fish, animals and plants and provide critical habitat for threatened or endangered species such as the California condor, mountain yellow-legged frog, arroyo chub fish and Nelson’s bighorn sheep.
  • The chaparral and oak woodland are just some of the vegetation that represent a portion of the rare Mediterranean ecosystem found in only 3 percent of the. The area also provides suitable habitat for 53 Forest Service Sensitive Plants and as many as 300 California-endemic species that only grow in the San Gabriel Range.

Scientific Discovery

A picture of the Mt. Wilson Observatory surrounded by a thick fog in the air. Science and research have been and continue to be an integral part of the monument area, most notably the Mount Wilson Observatory and the San Dimas Experimental Forest.

  • Edwin Powell Hubble, working from the Mount Wilson Observatory, is credited with making some of the most striking discoveries in modern astronomy, such as concluding that distant stars were really galaxies. That finding forever changed the way astronomers looked at the skies.
  • The San Dimas Experimental Forest, established in 1933, contains some of the earliest and longest records from continuously monitored, experimental watersheds in the U.S. It is the only research forest in Southern California, and many of the facilities were constructed by the depression-era Civilian Conservation Corps and Work Projects Administration labor programs. In 1976, the United Nations Educational, Scientific and Cultural Organization’s Man and the Biosphere Program recognized the San Dimas Experimental Forest as a “Biosphere Reserve.”  

Human dimension

A photo of two fishermen on floating tubes at Jackson Lake. The monument holds evidence of more than 8,000 years of human history, including more than 600 archeological sites, three of which are on the National Register of Historic Places, as well as ruins of old cabins and the Mount Lowe Railway. Other highlights are:

  • The area, which boasts more than 4 million visits, is host to a variety of year-round recreational activities, including hiking, cross-country skiing, hunting, nature viewing, picnicking, water activities and horseback riding and camping.
  • Mount Baldy Center adjacent to the monument helps to educate 8,000 students and teachers each year in environmental education and includes a 1920s schoolhouse, reproductions of a gold-mining camp and a Native-American (Tongva-Gabrielino) village.

Information about becoming a San Gabriel Mountains National Monument volunteer or partner is available from the Angeles National Forest.

Other Forest Service-managed national monuments:

Sources: U.S. Forest Service; U.S. Geological Survey, U.S. Fish and Wildlife Service, National Park Service, Carnegie Institution for Science