Turning A Barrier Into A Bridge For The Endangered SoCal Steelhead

A Caltrans project along Pacific Coast Highway will help the endangered Southern California steelhead trout return to their historic habitat in the Santa Monica Mountains.

Southern California steelhead trout

These giant fish in the salmon family used to be found all over the rivers and streams throughout Southern California, but their population has dropped off dramatically over the past few decades.

Kyle Evans is a senior environmental scientist supervisor with the California Department of Fish and Wildlife for the South Coast Region. He told LAist local residents in the 1940s and 50s used to be able to catch big, beautiful 2-foot-long silver steelhead trout right in Malibu Creek.

And a little further up north in Santa Barbara County, Evans said the city of Lompoc had an entire culture around steelhead and recreational fishing.

“It's a very important species historically,” he said. “Just from a recreational standpoint, from an ecosystem standpoint, from a cultural standpoint.”

Now, L.A.’s local steelhead population is in danger of going extinct within the next 25 to 50 years, according to California Trout. It’s been a federally endangered species since 1997.

What happened to their habitat?

Like other types of salmon species, these fish are born in freshwater. They spend their first couple years in the rivers and streams before choosing one of two general life paths, Evans said.

They can spend their entire life in the freshwater and reproduce there. These fish are called colloquially rainbow trout.

Or, they can choose to migrate out into the ocean. The young fish become smolts as they make their way through the saltwater, growing much larger and changing colors to a more silver shine. Those fish can eventually migrate back upstream, and those are known as steelhead trout.

Evans said one of the main reasons there’s been such a decline in the steelhead population is the land development and water use in Southern California.

In the Santa Monica Mountains particularly, the trout that move downstream out into the ocean aren’t able to go back into the freshwater because of manmade barriers like culverts, dams, or walls.

The 2018 Woolsey Fire also dumped a lot of ash and debris into the freshwater, which killed many of the fish living in the mountains. Evans said that area has largely recovered from the fire, but it still can’t be recolonized because the steelhead can’t make it back upstream.

“We've really limited the steelhead's natural habitat, the areas that they can access, the areas that they can get back to,” Evans said.

How will the Caltrans project help?

The more than $62 million project will upgrade stormwater drainage infrastructure along a 25-mile stretch of PCH, from the Pacific Palisades neighborhood all the way up to the Ventura County line.

Crews will be doing preventive work on 13 culverts in the area, but one specific location is getting a full makeover.

A map of where the new Caltrans bridge will be along PCH.

The culvert at PCH and Corral Canyon Road currently keeps the trout from spawning upstream in Solstice Creek, so Caltrans is going to convert that barrier into a bridge.

“The reason that we're doing this is this will allow the Southern California steelhead trout to be able to swim upstream during the rainy seasons when they can access that point,” Allison Colburn, a public information officer for Caltrans District 7, told LAist.

Colburn said Caltrans’ environmental group, in coordination with multiple government agencies, has recognized the need for a bridge for more than a decade. Now that the culvert needs some work anyway, Colburn said it’s a great opportunity to help restore the steelhead species locally.

Will the project impact drivers?

Caltrans is focusing their efforts on the actual bridge location at Solstice Creek first, so people can expect to start seeing construction crews out there next week, Colburn said.

Drivers should also expect some traffic switches along PCH.

Caltrans will be putting out a rail to shift the lanes for several months. That will allow crews to start working on the part of the bridge closest to the mountains.

There will be two lanes of traffic in each direction throughout the project, Colburn noted, with the exception of some overnight closures that will limit traffic to one lane in each direction at this specific spot.

The bridge is expected to be completed by late next year, and the rest of the restoration project will be done by 2025, Colburn added.

“It may be a little bit of a headache to drive through for some time, but it'll be over before you know it,” she said.

You can check quickmap.dot.ca.gov for the most up-to-date traffic information during this project.

Future of the fish

Evans said he appreciates Caltrans’ hard work, but there’s more to be done.

He hopes to work with landowners, cities, and other groups to see if there are other barriers that could be removed to open up the rest of the steelhead trout habitat.

Evans said that could be done on a small scale by removing a couple road crossings on Zuma Creek that cause barriers for fish to go up and downstream.

But it could also be on a big scale, he said, like removing the 100-foot tall Rindge Dam in Malibu Creek, which would open up a huge amount of habitat.

“This isn't something that just exists in Alaska, Oregon, and Washington,” he said. “We should have these big, beautiful salmon in our backyard that we can go experience, and look at, and enjoy, and fish. That's kind of the dream and the goal that we're working for.”