Caltrans is proposing the construction of a wildlife crossing over Highway 101, which could benefit the isolated mountain lion population in the Santa Monica Mountains/Caltrans

Help may be on the way for an at-risk population of mountain lions in the Santa Monica Mountains, as the California Department of Transportation intends to move forward with building a wildlife crossing over busy Highway 101, which could both help reduce the number of animals struck and killed by vehicles in addition to increasing the genetic diversity of the pumas by bringing new big cats into the area.

Caltrans last week released for comment its initial study and environmental assessment of a proposal to build a vegetated wildlife crossing over U.S. Highway 101 (the Ventura Freeway) west of Liberty Canyon Road in the city of Agoura Hills. The agency intends to adopt a Mitigated Negative Declaration on the project, based on studies that show it will not significantly affect the quality of the environment provided that the project incorporates certain measures such as vegetation and replanting, water quality permits, and post-construction monitoring.

Since 2002, the National Park Service and Santa Monica Mountains National Recreation Area have been studying how mountain lions survive in the increasingly fragmented and urbanized landscape near Los Angeles. Although the current population is stable, with healthy rates of survival and reproduction, a study last year predicted that the population faces extinction within 50 years due to inbreeding driven by major freeways and development hindering connection to other natural areas. In addition, 17 mountain lions have been struck and killed by vehicles in the study area in the past 15 years, including three in December and January alone.

"Fifty-plus years ago when the 101 Freeway was built, no one was thinking about wildlife connectivity," Dr. Seth Riley, a wildlife ecologist for the National Park Service, associate adjunct professor at UCLA, and senior author of the study said last year. "We have worked for years with our partners to increase connectivity across the 101 for all animals, but this study really drives home how serious the threat is for mountain lions, the species most at risk of being lost."

Another study released in May said that introducing even one new mountain lion would greatly improve the genetic diversity of the pumas. Highway 101 is the biggest barrier between the Santa Monica Mountains and other large natural areas.

The Liberty Canyon Wildlife Crossing would be the first of its kind in California. Similar wildlife crossings have been built and used successfully in other locations, such as Banff National Park in Canada. The project also includes the improvement of wildlife fencing along Highway 101, enhancement of habitat adjacent to the overcrossing structure through planting of native vegetation, construction of sound walls and retaining walls, and construction of a multi-use trail. If the project is approved and the funding is secured, construction is tentatively scheduled from May 2019 to November 2021.

The Caltrans project is being drawn up in conjunction with fundraising efforts by the National Wildlife Federation and Santa Monica Mountains Fund.

The IS/EA is available for review at www.dot.ca.gov/d7/projects/libertycanyon, the Caltrans District 7, Division of Environmental Planning Office (100 S. Main Street, Suite 100, Los Angeles, CA 90012) weekdays from 8 a.m. to 4 p.m., and the Agoura Hills Public Library (29901 Ladyface Court, Agoura Hills, CA 91301) weekdays from 10 a.m. to 5 p.m.

To comment

• Deadline: October 26, 2017
• Email: [email protected]
• Mail: Ronald Kosinski; Deputy Director, Division of Environmental Planning; California Department of Transportation; District 7, Division of Environmental Planning; 100 S. Main Street, MS-16A; Los Angeles, CA 90012
• In person: 6-8 p.m. October 12, King Gillette Ranch Auditorium, 26800 Mulholland Highway, Calabasas, CA 91302