Mount Baldy Wilderness Preserve is located off Mt. Baldy Road within a few miles of the historic mountain summit, along the border of Los Angeles and San Bernardino counties in the Angeles and San Bernardino National Forests. The preserve was acquired by Watershed Conservation Authority in 2014 to protect significant natural and scenic resources and critical wildlife and landscape connections to adjacent public lands owned and managed by the USFS. The preserve protects part of a 20-mile reach of San Antonio Creek, whose natural streambed reflects an unmodified flood regime. The preserve is flanked on the East and West by the Cucamonga and Sheep Mountain designated Wildernesses, both of which are habitat for big horn sheep.
Stay informed and get involved
For information and updates about Mount Baldy Wilderness Preserve, click here.
Hiking Trails
Mount Baldy Wilderness Preserve is the location of trailheads for popular trails. (Read trail reviews here).
Invasive Species Management- an ongoing effort
Invasive Spanish broom (Spartium junceum) is a rapidly growing species which increases fuel loads, displaces habitat for native wildlife, and interferes with public safety and enjoyment of this preserve. This species was present before WCA acquired the land, and continued to spread unchecked for many years. Inland Empire Resource Conservation District prepared an Invasive Species Management Plan (2020) for the preserve. A multi-year effort to remove this invasive species by California Botanic Garden and San Gabriel Valley Conservation Corps began in 2022 and continued until 2025. Because Mount Baldy Wilderness Preserve is downstream of properties where Spanish broom continues to occur, the effort to keep the Preserve free of this species will be ongoing until upstream sources of seed are eradicated. WCA seeks local partners to collaborate with on this effort.
Natural History of Mount Baldy Wilderness Preserve
- GEOLOGY
The topography of Mount Baldy Wilderness Preserve is formed by a landslide, which resulted in the landform endearingly named 'Hogsback.' This landform has been the topic of numerous articles and geology field trips.
Geology and Fracture Geometry in Source Region of Hogback Landslide by Reginald Agunwah (2020)
Hog Back: A grossly stable prehistoric translator rock block slide by Lawrence J. Herber (1987)
A Day in the Field with Tom Dibblee A Guidebook by Johnathan Nourse, Thomas Dibblee, and Peter Weigand (2003)
Geology and Hydrology in the Eastern San Gabriel Mountains by Kenney et al (2010)
- REPTILES AND AMPHIBIANS
The unique conditions provided by the geology of the canyon makes it home to a number of reptiles and amphibians.
Herpetofauna guide to the Preserve by William Flaxington (2023)
- BUTTERFLIES
At any given time of the year, observant visitors are likely to see butterflies in the canyon that would not be seen in the developed areas in the Los Angeles basin. That is because many butterflies found at the Preserve are associated with native plants on site for their life cycle requirements.
This butterfly collection of species found in San Antonio Canyon was created by Bill "Butterfly" Gendron, and is kept at Mount Baldy Lodge
- PLANTS
Glendora Naturalist Dick Swinney compiled this list of plants found at the Preserve
California Botanic Garden started this iNaturalist project for the preserve, and with the help of San Gabriel Valley Conservation Corps, expanded our record of plants at the Preserve.
