Devil’s Gate Dam Sediment Removal Project, Launching Tens of Thousands of Truck Trips Through Local Neighborhoods, Starts Tuesday

Published : Monday, May 20, 2019 | 5:44 AM

After years of controversy and court cases between naturalists and Los Angeles County, tens of thousands of truck trips through local neighborhoods removing built-up sediment behind Devil’s Gate Dam are set to begin Tuesday, weather permitting.

Opponents got a small reprieve. The hauling was to have begun Monday, but an updated weather forecast predicting rain throughout Sunday evening pushed the start back “until at least Tuesday morning.”

The massive effort is designed to haul out 1.7 million cubic yards of sediment which has built up behind the dam and threatens the dam’s ability to do its job controlling storm waters.

“Right now, the reservoir currently lacks capacity for even one major debris event,” said LA County Public Works spokesman Edel Vizcarra.

“If we were to get a large fire and some storms,  [we] wouldn’t be able to work with the equipment. Once that water goes over the spillway, you’ve pretty much lost control. The water going into the Arroyo, you have no control of it.”

The removal effort is gigantic.

Hauling out the volume equivalent of three Rose Bowls filled with sediment will require constant convoys of diesel trucks making as many as 400 daily round trips, eight months a year for four years.

Opponents say the manner in which the County has managed the dam and the sediment behind it has been heavy-handed, irresponsible and incompetent.

“Sediment management should be an ongoing maintenance responsibility, but the County has neglected that responsibility for many decades,” said Tim Brick, Managing Director of the Arroyo Seco Foundation. “Their long-standing negligence has compounded the negative aspects of the project.”

Brick said it is “shocking to see the massive amount of destruction of precious habitat and wildlife the County has wrought,” calling the sediment removal project “one of the worst environmental catastrophes in our region in many decades.”

Brick also took aim at the potential for air pollution in the neighborhoods through which the trucks will travel.

“It is incredibly irresponsible for County officials to claim that the diesel trucks they will use are up to the highest standards. Only the lawsuit filed by the Arroyo Seco Foundation and Pasadena Audubon Society forced them to upgrade the standards, but the 2010 level trucks they will use have been found to often massively exceed the regulatory standards,” Brick said Friday.

Vizcarra, however, points to the County’s responsiveness to public input on the project.

“We’d had over a hundred community meetings,” Vizcarra said. “We’ve been working with the surrounding cities … for close to 10 years now, trying to craft how this project is going to come together. It’s been a long process, but invaluable, because they have been able to help us plug things into this project that really, really improved it.”

Residents with questions or concerns about the project can call the Devil’s Gate Hotline at (626) 458-2507. For online information about the project visit