ASF Logo

Arroyo Seco Foundation

News of the Arroyo


Supes scale back Devil's Gate Big Dig sediment removal project





<b>November 16, 2017</b> - The County Board of Supervisors acts to reduce the size of their sediment removal program for Devil's Gate Dam in response to tremendous community concern.


Andre Coleman


Pasadena Weekly


The Los Angeles County Board of Supervisors voted 5-0 to scale back a major excavation project that could increase air and noise pollution and have negative impacts on the Hahamongna Watershed Park.

Under the new recommendations, 1.7 million cubic yards of sediment will be removed over five years from as part of the Devil’s Gate Dam Sediment Removal Project in Hahamongna park, managed the LA County Flood District.

Under the old plan, known as the Big Dig, 2.4 million cubic yards of sediment would have been removed over five years, requiring 400 daily truck trips into the area.

“This modified approach prioritizes safety, addresses environmental concerns and mitigates disruption for our local residents,” said Supervisor Kathryn Barger, whose district includes Pasadena and Altadena. Barger introduced the motion to scale back the project. “I appreciate the input of our concerned community members, environmental groups and the city of Pasadena who have participated in discussions with me and county departments over many months.”

The motion also calls for the county coordination with city officials on storm water capture and groundwater replenishment, as well as the development of an early warning system to notify downstream residents and businesses of any issues related to similar Los Angeles County Flood Control District facilities.

In March, local environmentalists claimed victory when LA County Superior Court Judge James Chalfant halted the removal of tons of sediment from Devil’s Gate Dam.

A significant amount of sediment has not been removed from Devil’s Gate since 1994, when workers hauled out 160,000 cubic yards of soil and debris.

An additional 1 million cubic yards of soil and debris were dumped into the basin by the Station fire in 2009, which burned more than 160,000 acres in Altadena, Pasadena, La Cañada Flintridge and Acton.

The project has been compared to Boston’s Big Dig, a $14.8 billion traffic tunnel project that impacted area residents for 15 years.




Arroyo Seco Foundation, PO Box 91622, Pasadena, CA 91109-1622 (323) 405-7326