Devil’s Gate Sediment Removal Project to Resume this Week

The construction phase of the Devil’s Gate Reservoir Restoration project will resume on Thursday, April 30 according to county officials.

The project was originally scheduled to begin today, but was postponed for later this week.

The LA County Flood District plans to remove 1.7 million cubic yards of sediment from the Devil’s Gate Dam reservoir, a job that is expected to take four years to complete.

A large 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.

According to the LA County Flood Control, the sediment compromises the dam’s ability to contain debris and floodwaters.

They say, if the sediment is not removed, locations along the Arroyo Seco downstream from the dam — including the Rose Bowl, and parts of the 110 Freeway and neighborhoods in West Pasadena — could be in danger of flooding.

Devil’s Gate is the oldest dam constructed by the LA County Flood Control District, providing flood protection for the cities of Pasadena, South Pasadena and Los Angeles.

“Critical infrastructure projects, like the work being done at Devil’s Gate Dam, are considered essential services by the state of California, and LA County Public Works is dedicated to a community-first approach as it moves forward in this multi-year effort,” the LA County Public Works Department said on its website.

Despite the dangers, preservationists worry about the potential impacts on Hahamongna Watershed Park. Local residents have long been fighting to maintain the 1,300-acre park as green space for families and hikers.

Located between Altadena and Pasadena in the Upper Arroyo Seco, Hahamongna provides access to foothill trails in La Cañada Flintridge and US Forest Service property further north, into the San Gabriel Mountains.

The park is managed by the city under guidelines laid out in the Hahamongna Watershed Park Master Plan,

Critics liken the job to the Boston’s Big Dig megaproject, which turned out to be one of the most expensive highway project in the US, and was plagued by cost overruns, delays and design flaws, charges of poor execution.

As part of the project in the Hahamongna, there could be hundreds of truck trips a day to excavate the material, increasing pollution.