USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

San Dimas Experimental Forest


Established in 1933, the San Dimas Experimental Forest is the only such forest in southern California. It covers 6,945 ha in the front range of the San Gabriel Mountains, located about 50 km northeast of Los Angeles. Originally established as an outdoor hydrologic laboratory to document and quantify the water cycle in semi-arid steeplands, most of the facilities were constructed by the depression-era Civilian Conservation Corps and Work Projects Administration labor programs. San Dimas has a long history as a research site in the fields of hydrology and ecology and is recognized as a Biosphere Reserve by UNESCO's Man and the Biosphere program. San Dimas also contains the Fern Canyon Research Natural Area.


San Dimas experiences a Mediterranean-type climate, with cool wet winters and hot dry summers.


Soils are characterized by steep topography, semi-arid climate, and crystalline bedrock (Precambrian metamorphics and Mesozoic granitics), which produce shallow, azonal, coarse-textured soils with numerous rock outcrops and low fertility.


San Dimas is covered primarily with mixed chaparral brushfields but also includes areas of coastal sage scrub, oak woodland, and mixed conifers. Some areas were type-converted from native chaparral to grassland during the 1960s.

Long-Term Databases

Long-term databases include precipitation, streamflow, stream nitrate, temperature, relative humidity, and solar radiation. Also, since 1982 San Dimas has been an air quality monitoring site for the National Atmospheric Deposition Program/National Trends Network.

Research, Past and Present

Research has included watershed hydrology, chaparral ecology, water yield, precipitation monitoring, post-fire erosion control treatments, soil non-wetability, hillslope erosion and watershed sediment fluxes, soil nutrient cycling, and bird habitat use.

Major Research Accomplishments and Effects on Management

Major accomplishments and effects of research at San Dimas include the development of rain gauges and raingauge networks to accurately measure precipitation in steep terrain, the development of flumes to measure and withstand debris-laden flows, and the identification of post-fire soil non-wetability.


Collaborators include professors of hydrology, soil science, environmental science, ecology, biology, geography, and geology from University of California- Riverside, University of Georgia, University of Iowa, California Polytechnic University-Pomona, Pomona College, and California State University-Long Beach.

Research Opportunities

Research opportunities include a broad spectrum of studies in the general fields of watershed hydrology, ecology, biogeochemical cycling, and fire effects.


Facilities at the Tanbark Flat community near San Dimas include a laboratory/office, residences, a mess hall/ conference room, and several storage/utility buildings. Infrastructure includes water, electricity, propane heating, and phone service. Research/monitoring equipment includes rain gauges, stream gauges, debris dams, water-quality samplers, a weather station, and a historical lysimeter complex.

Lat. 34°12´ N, long. 117°45´ W

Contact Information

San Dimas Experimental Forest Manager
USDA Forest Service
Pacific Southwest Research Station
4955 Canyon Crest Drive
Riverside, CA 92507
Tel: (951) 680-1538

Adams, Mary Beth; Loughry, Linda; Plaugher, Linda, comps. 2004. Experimental Forests and Ranges of the USDA Forest Service. Gen. Tech. Rep. NE-321. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 178 p.

1Information has been updated since original publication.