Bridge on track for Dec. 2 opening, officials say

For decades, the 101 Freeway has sliced through the Santa Monica Mountains like a wall, trapping wildlife — most famously the region's beleaguered mountain lions — on either side of ten lanes of concrete. In less than two months, that wall gets a doorway.

The Wallis Annenberg Wildlife Crossing in Agoura Hills is on schedule for a Dec. 2 opening, officials announced at an Oct. 8 construction update held at a trailhead off Agoura Road, just west of Liberty Canyon. The major structures are complete. What remains is landscaping, habitat restoration, and the delicate work of stitching the bridge into the hillsides around it.

"The finish line is in sight," Beth Pratt, regional executive director for California at the National Wildlife Federation and leader of the #SaveLACougars campaign, told reporters gathered at the site, according to The Acorn (Agoura Hills).

By now, most 805 residents have watched the crossing rise over the freeway — first as skeletal concrete pillars, then as a broad, planted deck that increasingly looks like a piece of mountain temporarily set aside. What's harder to see from the roadway is everything underneath and around it: relocated utilities, a buried electrical system, a rerouted water line, and a smaller companion bridge spanning Agoura Road itself.

Four projects in one

Pratt described the effort, which broke ground on Earth Day in April 2022, as four major construction jobs happening in coordination: the main span over the 101, the smaller crossing over Agoura Road, a complicated web of utility relocations, and 13 acres of habitat restoration on the surrounding land.

The price tag now stands at $114 million — roughly 23% above the original construction estimate of $92.6 million. The project was previously delayed by record flooding in 2022 and 2023, which disrupted soil compaction — the same kind of work crews are finishing now.

That history explains Pratt's one lingering worry: the weather. Forecasters are watching a potentially historic El Niño pattern that could stretch into early 2027. The only things that could still derail the opening, Pratt joked, are an "asteroid, earthquake or El Niño" — though experts expect the heaviest rains to arrive after Dec. 2. Erosion-control measures are already underway at the site, and Pratt quipped that for the first time in her life as a Californian, she's praying for no rain — or at least no flooding — until after the ribbon-cutting.

Why here, and why it matters

Anyone who has driven the 101 through Liberty Canyon knows the site isn't easy. Pratt addressed the frequently asked question directly: the crossing had to go in this exact spot because it's the only location in the region with continuous, protected habitat on both sides of the freeway.

"A lot of crossings would pick the easiest site to engineer," Pratt said. "We had the site picked for us."

She credited the Santa Monica Mountains Conservancy with decades of foresight. Rorie Skei, the agency's chief deputy director, recalled that when the land protection work began in the late 1990s, nobody was imagining a bridge. "We just wanted to protect the land on both sides of the freeway, so there'd be an opportunity in the future for animals to get across one way or another," Skei said. "It's been a real labor of love and a very difficult labor, but we're getting to the end."

The stakes are highest for the area's mountain lions, whose isolated populations suffer from dangerously low genetic diversity. The crossing is designed to reconnect the Simi Hills to the north with the Santa Monica Mountains to the south, giving big cats — and everything from deer to lizards — a safe path between the two ranges.

Mountain faces, restored

The final phase is, in a sense, an act of repair. Robert Rock, president and CEO of Rock Design Associates, which has worked with Caltrans on the design and construction, said crews are building large earthen mounds along the sides of the crossing that will rise above the freeway's elevation, shielding wildlife from the sights and sounds of traffic. The soil comes from the site's early excavation.

"What you're really seeing is … that mountain face restored that was cut away as the freeway was widened decades ago," Rock said.

Much of the habitat restoration will continue after the crossing opens, but the vegetation already established above the 101 is "flourishing," Pratt said — drawing hummingbirds, native bees, butterflies, western fence lizards and raptors. As for which animal will take the first official trip across, the smart money is on coyotes, which have been approaching the construction site daily.

The science begins when the ribbon falls

For researchers, opening day is when the real work starts. Seth Riley, a wildlife ecologist with the National Park Service, said scientists are fitting deer north and south of the freeway with radio collars and plan to use biological sensors — on deer and potentially mountain lions — to track heart rate, temperature and activity levels.

"So we'll be able to see, not just how do the animals move near the crossing, but how are they actually physiologically affected?" Riley said. "Are they happy to go up on there, and their heart rate doesn't change? Or what is it like to be near the freeway?"

Park Service biologists have been studying carnivores in the Santa Monica Mountains since 1996, and colleague Jeff Sikich noted that nine mountain lions are currently being tracked in the range.

For Agoura Hills, Dec. 2 promises to be more than a ribbon-cutting. It's the moment a decades-old idea — protect the land, and the animals will find a way — becomes something you can stand beneath, on Agoura Road, and watch come true.