Construction Begins on Devil’s Gate Reservoir Sediment Removal Project

Activists document the effects, vow continued opposition

Published : Thursday, December 6, 2018 | 5:51 AM

The first stages of work on a long-delayed and controversial sediment removal project have begun at the Devil’s Gate Reservoir in Pasadena, at the southern end of Hahamongna Watershed Park.

County officials say they’ve worked for years to minimize the impact to the local community and wildlife as much as they can. But some local residents say they still have serious concerns.

“We’ve actually got the contractor on site. They’ve begun work,” Los Angeles County Department of Public Works Deputy Director Dan Lafferty said. “ The first portion of the work was taking a look at the 70 acres that we have in preservation in perpetuity as part of our mitigation for the project, and improving the habitat in that 70 acres. So taking out all of the invasive species that are there and making those 70 acres a better habitat for California native species.”

The work will continue in the coming weeks.

“The next step then is the vegetation removal within the area where the sediments going to be removed,” Lafferty said. “That work is going to be going on through the end of January.”

Workers are also beginning work on an access ramp that will allow trucks to get in and out of the area without going through nearby neighborhoods, Lafferty said. “We’ve tried to make sure that those routes are as least impactful to the community as possible.”

Work on the ramp part of the project will be suspended over the holidays, from Dec. 17 to Jan. 6, he added.

“We’ll do what we can to make sure that we’re being as respectful as we can be as we do this project,” Lafferty said.

“What we’ve tried to do is to balance reducing the flood risk that the current conditions pose to those downstream residents with the project’s impacts to those who are actually at the project site,” he said.

Arroyo Seco Foundation Managing Director Tim Brick said he doesn’t dispute that the work is necessary, but there are better ways to go about it that would be less impactful, both to nearby neighborhoods and the environment.

“We’ve never been against them doing a sediment management program, but we’ve been telling them for 30 years, really, that they should be doing it on a regular, ongoing basis,” Brick said. “The sad fact is that they haven’t removed any sediment in a substantial amount for 25 years. So now they’re finally starting to remove sediment site.”

“Our concern is they’re doing it too fast,” he said. “They’re going to try to undo what they haven’t done in the last 20 or 30 years. They’re going to try to undo that in the next three or four years and the impacts on the neighborhood, the noise, dust, pollution and all of that is going to be quite extreme.”

Extending the project out over a longer timeframe would be far better from multiple perspectives, Brick said.

“If they stretched it out and did it in 10 years, for instance, they could dramatically reduce the real impacts on the neighborhood on air pollution and even on the environmental destruction that they’re creating,” he said.

“Our basic feeling is that they need to do a regular ongoing sediment removal program that is sensitive to the environment and that goes in and surgically picks areas to remove sediment where there’s a lot of sediment rather than just digging a big pit in the middle of the basin for their trucks and bulldozers to destroy,” Brick said.

“They’re going to come in every year and destroy the habitat in that rare precious stream zone there. And that’s going to be very detrimental really to the whole basin,” he said. “The long-term impact of the project, the way the county now plans, will be devastating to the wildlife corridor and to water resources in the area.”

And then there’s the traffic congestion that will accompany the work, Brick said.

“I’m hearing a lot of rumblings from people who are very upset about it already,” he said. “There’s a petition that has been circulating. It’s now up to 5,000 signatures.”

“We’re not going to stop until the County really restructures this project… and comes up with a more sustainable approach to protecting Hahamongna,” Brick said.

While Lafferty said he understands the concerns of neighbors, “There’s just no other choice.”

“It’s unfortunate that in the community that surrounds the reservoir has to go through that process, but trucking, in this particular instance, is the only option we have.”

He added that the current project has a 10-year permit. It includes four years for the initial sediment removal project, followed by six years of ongoing maintenance.

“Every year we’re going to get inflows,” Lafferty said. The San Gabriel Mountains are among the most erosive in the world, he said.

“So we’ll make sure that for the duration of that permit cycle that we’re going to be annually removing the amount that does come in,” he said.

No solution will satisfy everyone’s concerns at the same time, Lafferty said. “But we feel like we’ve done a pretty good job of accommodating the different perspectives that we’ve heard during the development. It’s been 10 years in development and so I think we feel like we’ve done a good job of balancing those.”

Updates on the project are available on the County’s website at