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Local “Big Dig” Sediment Removal Project at Devil’s Gate Reservoir Completed, One Year Ahead of Schedule

Published on Tuesday, August 3, 2021 | 10:22 am
Supervisor Barger and Public Works Director Mark Pestrella at Devil’s Gate

A Los Angeles County project to remove 1.7 million cubic yards of sediment from Devil’s Gate Reservoir in the Hahamongna Watershed Park has been completed more than a year ahead of schedule, Los Angeles County Supervisor Kathryn Barger announced on Tuesday.

“The County’s goal of restoring flood protection to communities downstream of Devil’s Gate Dam has been achieved with a level of robust community engagement that makes the project a model of collaboration, safety, sustainability and innovation,” Barger said in a statement.

According to a report in the City Council Public Safety Committee agenda from earlier this year, 532 cubic yards of sediment were removed in 112 hauling days last year.

In addition to providing flood relief to communities that have endured more than a decade of elevated flood risk along the Arroyo Seco, the project will establish a permanent stormwater maintenance area that allows for the creation of 70 acres of enhanced habitat and recreational opportunities.

Devil’s Gate Dam was built in 1920 by the Los Angeles County Flood Control District to provide flood protection to communities in the Lower Arroyo Seco watershed. The 2009 Station Fire burned more than 160,000 acres of the San Gabriel Mountains, and subsequent storms brought in more than a million cubic yards of sediment into Devil’s Gate Reservoir

“On behalf of the residents of Pasadena, particularly those who live in and around Hahahmongna, I’d like to thank our County partners for completing this project nearly one year ahead of schedule,” said Pasadena Mayor Victor M. Gordo. “Now it is time to restore the native plants and habitat. I look forward to working with Supervisor Barger and County staff to accomplish this in the near future,” Gordo continued.

The Devil’s Gate Reservoir Restoration Project began in December 2018. Managed by Los Angeles County Public Works, the project’s sediment removal operations began months later in May 2019 with the goal of removing the equivalent of three Rose Bowls full of sediment that had accumulated behind the dam. The project was designed to restore the facility’s flood control capacity while establishing a permanent maintenance area surrounded by 70 acres of native habitat and various recreational opportunities.

Crews will perform construction finishing activity within the reservoir through November of this year. The habitat enhancement component of the project will continue

“First, I want to thank all the neighbors and neighborhood groups that worked to ensure the project was being done as mindfully as it possibly could to minimize impacts on the native wildlife and the nearby residents,” said District 1 Councilmember Tyron Hampton. “I’d also like to express my gratitude to Supervisor Barger who diligently worked on the concerns that were raised to get us to the point we are today. The project is not yet complete, but I’m excited that the Big Dig is behind us. The next phase of the project involves native plant restoration, and I look forward to once again working with the Supervisor and the neighbors. I am very grateful to everyone for their continued engagement.”

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One thought on “Local “Big Dig” Sediment Removal Project at Devil’s Gate Reservoir Completed, One Year Ahead of Schedule

  • It is nice that this part of the project has been completed ahead off schedule, but there are now issues with the settlement ponds being increased in size and the taking of water from the stream above the Devils Gate Dam inside the canyon. There is apparently a new dam that is to be constructed and the building of the dam and taking more water will damage the habitat of the rainbow trout living in the lower part of the canyon. These projects to be implemented by the Pasadena Water and Power Department need more development to avoid the degradation of the stream environment and the harm to the fish population in the stream especially in this current drought situation.