By Alex Dobuzinskis

LOS ANGELES, Sept 3 (Reuters) - Officials have unveiled plans for a grassy bridge over a Southern California highway that would provide a safe and natural passage for mountain lions and other animals migrating between wilderness areas.

The vegetation-lined bridge over the 101 Freeway in Agoura Hills, just west of Los Angeles, would cost $30 million to build and construction could not begin for years, said California Department of Transportation (CalTRANS) spokeswoman Lauren Wonder.

The Mountains Recreation and Conservation Authority, a government agency, funded a CalTRANS report on the proposed bridge and on Wednesday released the document, which said it was achievable.

The project is seen as an innovative approach to make the 101 Freeway less of a barrier to mountain lions, bobcats, gray foxes and mule deer, all animals the conservation authority said migrated with ease between the Santa Monica Mountains and the Simi Hills before the freeway blocked their path.

A mountain lion tracked by wildlife biologists and labeled as P-32 in April crossed the 101 Freeway in a quest for virgin territory, which wildlife officials heralded as a rare feat. But last month, P-32 was struck and killed by a vehicle on Interstate 5 in Southern California, officials said.

Mountain lions in the Santa Monica Mountains suffer from inbreeding because of they are restricted to areas smaller than their historic ranges, according to the conservation authority.

"Science militates that we construct the highest functioning wildlife crossing to ensure the survival of our native species, including mountain lions, in the local mountains," Joseph Edmiston, executive director of the Santa Monica Mountains Conservancy, said in a statement.

A number of elected officials including U.S. Representative Ted Lieu, a Democrat representing Malibu and nearby areas, and California state Senator Fran Pavley, a Democrat from Agoura Hills, support the bridge concept.

An environmental study is needed before the project can proceed, and it would be built with public and private funds, Wonder said.

Animals sometimes pass through culverts to cross the 101 Freeway around the site where the bridge would be built, Wonder said, but the creatures often overlook those passageways and instead find themselves stuck in lanes of traffic.

Europe has many wildlife crossings at highways, said Dash Stolarz, a spokeswoman for the conservation authority. In the United States, structures built over and under U.S. Route 93 on the Flathead Indian Reservation in Montana allow wildlife to migrate through wildlands. (Reporting by Alex Dobuzinskis; Editing by Daniel Wallis and Sandra Maler)