TEMECULA, Calif.— Conservation groups approved a legal agreement today that will protect a critical wildlife corridor for local mountain lions and other wildlife, fund restoration efforts and ensure implementation of a regional conservation plan. The agreement comes after a judge issued a ruling this spring against the proposed 270-acre Altair development in Western Riverside County in California.

The agreement permanently protects the 55-acre “South Parcel” — a key part of one of the only passages left for endangered Santa Ana mountain lions to move between coastal and inland mountains. This lion population suffers from extremely low levels of genetic diversity due to limited wildlife connectivity.

“This agreement gives Santa Ana’s imperiled mountain lions a pathway to recovery,” said J.P. Rose, an attorney at the Center for Biological Diversity. “Poorly planned highways and development have hemmed this population in, and these beautiful big cats are being driven toward extinction. Now they have a better chance at survival.”

The agreement redesigns the development to minimize impacts on mountain lions, western pond turtles and other rare species. It also requires the developer to acquire other conservation lands for regional connectivity, establishes an education program for coexistence with wildlife, and allows for the future acquisition of more of the development site for conservation.

“We thank the city of Temecula and Ambient in helping us keep the parcels next to the headwaters of the Santa Margarita River intact, thus avoiding an impact that would have almost certainly ensured the extinction of the Santa Ana lions,” said Pam Nelson of the Sierra Club’s Santa Margarita Group. “Their fragile status indicates the health of all the species in our region. This agreement will give these magnificent creatures and struggling wildlife a chance.”

The legal agreement comes as state wildlife officials are studying whether to grant the Santa Ana mountain lions and five other cougar populations permanent protections under the state’s Endangered Species Act. The Center and Mountain Lion Foundation petitioned the state to protect these populations in June 2019, and in April 2020 the state Fish and Game Commission advanced these populations to candidacy under the Act.

“With our planet in the midst of an extinction crisis, we can no longer afford business as usual. This agreement includes significant measures to help to ensure the survival of our big cats, their habitat and the diverse wildlife species the lions support,” said Debra Chase, CEO of the Foundation.

Some Southern California lion populations could disappear in little more than a decade, according to a March 2019 study. This study, involving a large team of researchers from the University of Nebraska, UCLA, University of Washington, UC Davis, National Park Service, University of Wyoming and Northern Arizona University, warns that if continuing inbreeding occurs, the Santa Ana Mountains population could go extinct within 12 years and the Santa Monica Mountains population within 15.

“This agreement marks an important step in the fight to protect the Santa Ana mountain lions, and we look forward to collaborating on future efforts to plan and fund the restoration of corridors for these big cats,” said Vicki Long of Cougar Connection.

The conservation groups filed a lawsuit against the development in January 2018, with Endangered Habitats League filing a concurrent lawsuit. In March Judge Daniel Ottolia found that the development’s environmental review failed to properly account for impacts on the Santa Ana mountain lions. The ruling also found that the development was not consistent with Temecula’s general plan or the Western Riverside County Habitat Conservation Plan.

As part of today’s agreement, the conservation groups are dismissing their legal challenge to the development.