It’s easy to be jealous of creative creation myths when you’re trying to construct a mountain above one of the busiest freeways in the nation and see how natural areas were created with a simple hand gesture.
There were no water lines to move or overhead wires to hide in those stories. There were automobiles to avoid, underground creeks that needed to be stabilized, magnificent oaks that needed to be preserved, or soils that needed to be inoculated with microorganisms from the area.
Such are the impending difficulties for the architects and builders of the Wallis Annenberg Wildlife Crossing, the biggest and most ambitious crossing in the world, which was created in Agoura Hills to provide wildlife with a safe and natural-looking route across the 10-lane 101 Freeway.
The crossing structure itself is essentially a bridge to nowhere at the moment, crouching over the freeway just west of the Liberty Canyon Drive offramp. The only thing left to do is plant, which will take place this fall. (However, news flash! The first non-insect animal seen on the bridge last week was a Western fence lizard sunning at the top, about 75 feet above the traffic below, despite the fact that it is not connected to the nearby hills.
Installing the connectors on the structure’s shoulders, which will allow wildlife that is separated by freeways to move between the Santa Monica Mountains to the south and the Santa Susana Mountains to the north, is the second and last stage.
In addition to boosting the health and genetic diversity of everything from lizards to mountain lions like P-22, whose lonely existence in Griffith Park served as inspiration for the crossing, expanding the places where wildlife can travel securely will increase their chances of meeting mates.
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One of the most well-known cats in the world is L.A.’s P-22. Does he need a Batman, Big Bird, or Lassie star?
Robert Rock, the chief executive of Chicago-based Rock Design Associates and the landscape architect in charge of the $92.6-million project, said that this second phase is the most challenging, particularly the south-side connection over Agoura Road.
The construction of the 54-foot-wide tunnel that will span Agoura Road on the south side will involve burying overhead wires close to the site, moving water lines for the Las Virgenes Municipal Water District, stabilizing an underground creek (known as No-Name Creek) that runs beneath the tunnel site to prevent erosion, and driving two walls of pilings deep into the ground for 175 feet along Agoura Road.
In order to cover the tunnel and create the sloping connecting shoulder into the Santa Monica Mountains, workers will literally be moving a small mountain of soil from the north side of the freeway, where it was piled when this section of the 101 was built in the 1950s, once the tunnel is built and the concrete roof is poured.
More native trees, shrubs, and perennials will be planted on the shoulders as the last step. Two miles of galvanized steel fencing will be erected on either side of the crossing to direct animals over it and away from houses and roads that have been constructed by humans.
Simple, isn’t it? With one exception, they must complete all of the construction and earthmoving without upsetting the expansive grove of natural oak trees that surrounds the property.
Rock stated, “It’s a tricky pocket.” Without a doubt, we’re threading a needle.
The designers are making every effort to preserve the native trees that are growing around the property, but he acknowledged that some of the lesser trees could need to be taken down. With native plants grown from seeds collected within three miles of the project and soil specially inoculated with local fungi and microbes to enhance their growth, it is not surprising that the entire project has focused on re-creating nature as much as possible on a foundation of concrete and steel. The project nursery, located a few miles away from the site, is caring for the plants.
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The process of gathering native seeds and constructing a nursery to cultivate them has started, even though the Wallis Annenberg Wildlife Crossing over the 101 Freeway won’t open until late 2025.
According to Rock, the Valencia-based contractor C.A. Rasmussen Inc., who completed the project’s first phase, has also been awarded the bid to complete the second. The crossing’s final completion date has been moved to the end of 2026 because to weather delays, mostly caused by severe rains in 2022 and 2023. As part of its 30 by 30 initiative, which aims to conserve 30% of the state’s lands and coastal waters by 2030, California has contributed $58.1 million of the $92.6 million project. Private donations are providing the remaining monies.
Next week is anticipated to see the start of work on the last stage. Agoura Road will need to be partially closed for a large portion of the preparatory work and tunnel construction, although the builders must give 30 days’ notice before the closures start.
Rock stated that he anticipates that during the day, when the contractor will be operating, Agoura Road will only be partially blocked to bike and car traffic. The precise closure hours are still being worked out with the city of Agoura Hills. According to him, the closures are anticipated to start in early August and continue for a number of months.
He stated, “I hope we can be done by the end of the year, but I can’t really say [how long] beyond several months worth of impacts.”
A special cover crop of four native plants, spring golden yarrow (Eriophyllum confertiflorum), California poppy (Eschscholzia californica), giant wildrye (Elymus condensatus), and Santa Barbara milk vetch (Astragalus trichopodus), has already started to grow on the main structure. These plants were chosen because they thrived when mycorrhizal fungi and other microbes were added to the soil.
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A California native plant landscape can seem a bit dismal without careful planning, particularly in late summer when many plants lie dormant. These 13 are sure to bring vibrant color.
It was not surprising to see at least one invasive black mustard plant on the crossing last week, given that the nearby hills were covered in the quickly spreading, invasive mustard earlier this spring. However, Rock stated that contractors are expected to keep those invasive plants weeded out to allow the natives to establish themselves.
According to Beth Pratt, California regional executive director of the National Wildlife Federation and the leader of the Save LA Cougars campaign, who is in charge of project funding and fundraising, hundreds of native plants that were raised from seed in the project’s adjacent nursery will be planted on the crossing this fall, most likely in October.
For anyone who wish to boast about cultivating six of the native plants that will be prominently displayed on the bridge, Save LA Cougars is offering a blend of six native seeds from Pacific Coast Seed (previously S&S Seed).Ashyleaf buckwheat (Eriogonum cinereum), black sage (Salvia mellifera), showy penstemon (Penstemon spectabilis), common deerweed (Acmispon glaber var. glaber), thin leaf milkweed (Asclepias fascicularis), and foothill needlegrass (Stipa lepida)
A package of the keepsake seeds costs $10 and can be ordered online. The project’s nursery, which is highlighted in a recent Save LA Cougars film detailing the selection and care of all the native plants, soils, and compost at the crossing, will be supported by the proceeds.
Meanwhile, a new finance worry for the project has been introduced by the latest tariffs. Pratt stated that it is currently unclear if additional fundraising will be required to meet all of the increased expenses.
We are able to move forward [with Stage 2] because Robert [Rock] and CalTrans have been working nonstop to rethink and value-design in order to reduce the expenses, Pratt stated. The collaboration has been outstanding.
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According to Pratt, the design changes appear to have kept the additional costs under control for the time being. However, they could need to gather additional funds to cover unforeseen costs, such as the two miles of extra-tall fencing, which Rock believes will cost around $2 million. I believe we are at peace now that they have taken them down once more.
Even though the bare landscape currently resembles a moonscape, the Western fence lizard seems to be establishing a home somewhere above the incomplete crossing while all these human problems are taking place. When Pratt saw the little reptile while escorting a small group of guests, she paused to consider its significance.
One of the most prevalent creatures in California is the Western fence lizard, which I frequently see in my yard and everywhere else, Pratt stated in an email. Then it dawned on me to wait. There’s a lizard on the bridge! And I’ve never seen an animal on the bridge before! I halted the gathering and informed them that they were witnessing the first animal on the actual bridge. Everyone applauded. The lizard appeared to be aware that it was a unique occasion. He posed for my pictures.
