Environment & Science

LA gets its first look at proposed bridge for mountain lions, wildlife

Project planners released the first details of a proposed wildlife bridge that would cross over 10 lanes of traffic along the 101-Freeway in Agoura Hills.
Project planners released the first details of a proposed wildlife bridge that would cross over 10 lanes of traffic along the 101-Freeway in Agoura Hills.
Resource Conservation District of the Santa Monica Mountains

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The Santa Monica Mountains are a rare juxtaposition of nature and urban development — a place where millions of humans can walk the same paths used by wild animals such as mountain lions.

That coexistence has not been balanced, however, and resident wildlife populations have become increasingly genetically isolated — cut off from access to other wild lands by highways and housing. Inbreeding is widespread within the population of Santa Monica Mountain cougars, which are now among the most genetically isolated in the country.

It's hoped that another human development will help remedy the situation. Conservationists have long called for a safe passageway for animals to cross into and out of the mountain range. Several attempts have been made to plan a tunnel under the 101 Freeway. All have failed.

Now, an even more grand-scale idea for a crossing has captured public and political support and has made it the furthest of any proposed project yet. Project leaders on Thursday released initial plans and cost estimates for a 165-foot wide and 200-foot long overpass that would cross the 10 lanes of the 101 Freeway at Liberty Canyon in Agoura Hills.

The bridge would be covered in vegetation, making it a more palatable passageway for wildlife crossing between the Santa Monica Mountains and the Simi Hills to the north, according to the proposal released by the California Department of Transportation. 

Researchers said they were excited to see the progress that has been made. 

“It’s pretty exciting to have it be a little more real, you know, have some actual diagrams and some ideas of the kinds of things that it would look like and to have an idea about the cost as well,” said Seth Riley, a wildlife ecologist with the Santa Monica Mountains National Recreation Area. 

Riley said even slight usage of the crossing would be a boon for the wildlife population. 

“Increasing the movement across the freeway for something like mountain lions even a little bit can make a big difference,” Riley said. 

"We saw in our previous work that one animal making it across, P-12, and then successfully mating made a big difference. Although then, when he has started to mate with his daughters and granddaughters, then that can start to negate the positive difference that him coming across makes,” he said.

Cost and fundraising

The estimated cost for the overpass is about $30 million. Full realization of the project, including a tunnel across Agoura Road, could near $60 million, according to the report. The need for the second crossing is unclear as of yet, though, as vehicular traffic along Agoura Road is relatively light. 

Still, the initial $30 million cost is steep. Organizers, however, are optimistic about their ability to raise funds for the project, especially now that the project study report has been released.

“This allows us to get to the next phase. We’ve been advocating for something that we weren’t even sure what it looked like or what the costs were or if it was feasible, so obviously that’s a little vague,” said Beth Pratt-Bergstrom, California director of the National Wildlife Federation.

“This allows us now to really hit the fundraising path hard, because now we have a product we can deliver,” she said.

On Thursday the campaign released a video, starring actor Rainn Wilson, calling for text-to-donate contributions. 

Fundraising video featuring Rainn Wilson

The #SaveLACougars campaign has raised more than a million dollars, but Pratt-Bergstrom said a greater push can now be made. She said the campaign aims to raise the money in time to keep construction on schedule. 

“That is our campaign goal. We want the $31 million in the bank by 2018, so that there’s no pause, and that crossing will be built,” Pratt-Bergstrom said.

Funding for the project is expected to come from a variety of public and private sources. Paul Edelman, chief of natural resources and planning for the Mountains Recreation and Conservation Authority, said a good portion of the money could come from mitigation dollars that would arise from future widening projects elsewhere along the 101 Freeway.

"It may be that there is a way to generate a good portion of that funding as mitigation for that expanding the width of the freeway to go into this pot,” Edelman said.

All in on a bridge?

Though tunnels under the 101 Freeway had previously been the hope for a crossing, options for such a tunnel were not included in the study report. Edelman said the hassles of constructing such a tunnel made it unfeasible.

“To construct it, they would actually have to shut down the freeway for periods of time, and we just all agreed that the cost of doing that and the disruption — but more importantly the not-as-equal function for wildlife as the overpass — made it that if we were going to go in this direction, we wanted to leave that tunnel option off any kind of detailed study for this point,“ he said.

Edelman said if the proposed bridge is constructed, it would be the widest of its kind in the world. He said the wide range of use, as well as the novelty, it would provide, would make it a valuable addition to Southern California.

“It’ll have dual use. In the daytime, there won’t be many animals using it at all, so if people use it on mountain bikes, or horses, or whatever, power to them. It will add kind of a key, fun recreational feature to our area,” Edelman said. “Who knows, it might even become the type of thing where people come from miles around to look at it and spend money in the local economy, it’ll be that cool."

Seth Riley of the National Park Service said the high-profile project would be a symbol for the area. 

“If this were to happen, it would really be a huge and very visible statement about how much the people of Southern California care about wildlife and wild places,” Riley said.

Project Study Report for the Liberty Canyon Wildlife Crossing