Habitat Restoration

The term “habitat restoration” refers to the process of restoring the functional aspects of a given ecosystem to a semblance of its pre-disturbed state. As a result of more than 100 years of human land use, much of the Puente Hills contains disturbed habitats that are now dominated by non-native vegetation. Non-native vegetation includes weeds, such as non-native grasses, mustard, castor bean, and tree tobacco that create high wildfire risk and result in low value habitat for wildlife. Past land uses that have created or contributed to disturbed habitats include livestock grazing, grading, development, intentional planting of non-native vegetation, and the use of invasive vegetation on properties adjacent to open space which then spread into natural areas. Our goal is to put our natural areas back in order for the benefit of future generations and for the wildlife that call the hills home. As such, the Habitat Authority actively restores areas by removing non-native vegetation and replacing it with native vegetation that would have been present prior to the disturbance.

Over 300 acres of Habitat Authority lands on the Puente Hills Preserve have been or are currently being restored/enhanced. This includes 182 acres of mitigation restoration that are regulated by state and federal natural resource agencies, and 119 acres of general enhancement and restoration. Restored habitats on the Preserve include coastal sage scrub and sycamore riparian habitats at the Hacienda Hills Trailhead; coastal sage scrub restoration on the former Unocal property (east of Colima Road in Arroyo San Miguel); coastal sage scrub at the Arroyo Pescadero Trailhead; and oak and walnut woodland, coastal sage scrub, native grassland, and riparian habitats in Powder Canyon.

The following are examples of habitat restoration projects on Habitat Authority lands that were either initiated and conducted by the Habitat Authority or implemented through the mitigation process with oversight by the Habitat Authority.


Powder Canyon In-Lieu Fee Mitigation (La Habra Heights)

As mitigation for Segments 7 and 8 of the Tehachapi Renewable Transmission Project (TRTP), Southern California Edison is working with the Habitat Authority to restore 53 acres of coastal sage scrub and 7 acres of oak and walnut woodlands. The project was initiated in 2016, seeds and container plants were installed in 2018 and the sites are currently being maintained and monitored while the habitat establishes. Click here for more information.


Before (2014) Current (2020)


Before (2014) Site Cleared (2017) Current (2020)


East Colima In-Lieu Fee Mitigation (Whittier)

Once a forest of eucalyptus, the Habitat Authority conducted coastal sage scrub mitigation on this 15-acre site. By year two of restoration, federally threatened coastal California Gnatcatchers were already using the site for breeding. The photos below were taken before restoration was initiated (2009), after the site had become established (2014), and five years post-restoration (2020). This project was cited in the Whittier Daily News on January 13, 2010 shortly after plants were installed and again in the San Gabriel Valley Tribune on May 8, 2016 after restoration activities were concluded and the site had received approval from the regulatory agencies.



Current (2020)


Former Canlas Property In-Lieu Fee Mitigation (Whittier)
The Habitat Authority, in cooperation with the United States Fish and Wildlife Service, initiated the restoration of this 8-acre property in 2005 which previously supported non-native grasses and other invasive vegetation. The site was planted and seeded in 2005 with coastal sage scrub species and has since provided the federally threatened coastal California Gnatcatcher with valuable foraging habitat.


Before (2005) During (2007) After (2014)


Former Diaz Property Restoration (La Habra Heights)

The former Diaz property previously contained an uninhabitable house, an avocado orchard, and other nonnative vegetation which were removed and replaced with native vegetation. The Habitat Authority restored 25 acres on this property to coastal sage scrub and oak/walnut woodland habitats.



Former Unocal Property Permittee Implemented Mitigation (Whittier)

The Habitat Authority has facilitated approximately 52 acres of habitat restoration on the former Unocal property (Arroyo San Miguel) as mitigation for local development projects, including coastal sage scrub and riparian restoration. As proof of its success, the federally listed coastal California Gnatcatcher is frequently documented within the restored coastal sage scrub, including successful breeding as determined by focused bird surveys across several years. All of the photos shown below were taken in May 2008.


Sycamore Canyon Permittee Implemented Mitigation (Los Angeles County unincorporated)

Approximately 3.5 acres in the lower portion of Sycamore Canyon was restored in 2007 with sycamore riparian woodland vegetation. The restoration was conducted as mitigation for a development project in Claremont.


Before (2004) 2008 2008