Calabasas continues cleanup at Las Virgenes Creek

Old concrete
debris, invasive plants removed

BRANCH OFFICE—A worker removes one of 250 invasive pepper trees along Las Virgenes Creek to make room for new native tree saplings, all part of an ongoing creek restoration project. Courtesy City of Calabasas

BRANCH OFFICE—A worker removes one of 250 invasive pepper trees along Las Virgenes Creek to make room for new native tree saplings, all part of an ongoing creek restoration project. Courtesy City of Calabasas

For the second time in a decade, the City of Calabasas will tear up the concrete-lined surface of its landmark creek and restore it to its natural state.

As the city grew over the years, workers and builders changed the course of Las Virgenes Creek, filled it in with concrete channeling and lined it with nonnative trees.

On Feb. 15, work began on a $1.8-million project that will restore the natural habitat of the creek between Agoura and Lost Hills roads on the west side of town. In addition to its deep concrete walls, the creek is filled with debris, dead brush and invasive trees that block the flow of water.

In 2008, the city completed the removal of 440 feet of concrete channeling in Las Virgenes Creek next to the Albertsons shopping center on Agoura Road.

Both jobs stem from a 30-year-old commitment by the state to assist communities with restoring their creeks and streams to a more natural state, while making sure the waterways still had the ability to serve as floodcontrol channels.

Alex Farassati, Calabasas’ environmental services supervisor, said the latest restoration work focuses on a stretch of the creek just north of De Anza Park.

“We’re going to build walking trails, a multi-purpose trail. We’re going to stabilize the banks, remove the fish barriers and plant about 1,300 oak trees,” Farassati said.

“We are removing a concrete retaining wall that’s broken down. It’s holding the bank that’s holding Lost Hills Road, part of it. That segment of retaining wall has broken and shifted about 15 feet, right in the middle of the creek. All the water is actually going behind the retaining wall now, it’s so bad,” he said.

The city is paying for the project with grants from propositions that fund environmental restoration projects. The city is also using money from its general fund.

As part of a deal with the city to expand its campus, Viewpoint School is paying for the oak trees that will be planted as part of the restoration.

Farassati said he expects the project will be done by December this year. When it’s completed, there will be two new trails along the creek, one of which will comply with the Americans With Disabilities Act, and an outdoor education area with a gazebo and park amenities.

Concrete channeling will have to remain in certain sections of the creek, as they support the bank, which is directly next to Lost Hills Road. Farassati said that where sections can be removed, rocks and other natural materials will be used to stabilize the banks.

Construction will also eliminate a 10-foot drop in the creek, south of the concrete channel at Meadow Creek Lane, which has blocked fish from moving up the creek. The restoration will fill the drop with rocks and dirt, reducing it to two feet. The channels will also be narrowed and construction will create small pools that will help fish travel through the creek.

The restoration will undo work that was initially installed over 50 years ago.

“After the second world war that was the concept—to carry rain and stormwater quickly to the ocean, to prevent any flooding in communities,” Farassati said.” The way we see Lost Hills Creek now is not the original route; it used to meander throughout that region. They probably wanted to improve that area and develop it, so they straightened out the creek. The velocity of the water is much faster than it used to be. In order to protect the banks, they chose to put a concrete channel in different segments. We removed one but there are two others we can’t remove because they’re holding the road.”

He said the city has been removing trees from the area for two years in preparation for the restoration. The city took down about 500 trees—palms, pepper trees and eucalyptus trees that are not native to the region.

Although some residents expressed concern, Farassati said the trees were killing native species and taking too much water.