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Arroyo Seco Foundation

News of the Arroyo


LA County Supervisors approve scaled-down sediment removal project for Devil's Gate Dam in Pasadena





<b>November 7, 2017</b> - In a major turnaround, the County Supervisors today voted to scale down the Flood Control District's massive sediment removal program for Hahamongna from 2.4 million cubic yards to 1.7 million.


Steve Scauzillo, San Gabriel Valley Newspapers


Pasadena Star-News


Ronnie Blaszczyk, 57, of Pasadena hikes along one of the trails at Hahamongna Watershed Park in Pasadena, just below Devil’s Gate Dam on Saturday, Sept. 16, 2017.

A scaled-down project that removes less sediment, debris and vegetation than planned from behind Devil’s Gate Dam in Pasadena was approved Tuesday by the Los Angeles County Board of Supervisors.

Instead of 2.4 million cubic yards, the project was trimmed to remove 1.7 million cubic yards from a natural area within Pasadena’s Hahamongna Watershed Park. The compromise, proposed by Supervisor Kathryn Barger, marks a turning point in the controversial project initially approved by the Board in 2014.

But a Los Angeles Superior Court judge later ruled against the project, saying the plans didn’t do enough to protect local wildlife, and forced a re-vote.

The smaller project received praise from the city of Pasadena, officials in Altadena and local environmental groups who have fought what they’ve called “The Big Dig” for the last three years.

“Now, this will allow a better base for the habitat and for the birds and wildlife. It is a very big change from what they were proposing,” said Tim Brick, managing director of the Arroyo Seco Foundation, which along with Pasadena Audubon won a partial court victory in April.

The Barger plan was a compromise between the Public Works plan and the Pasadena plan, which called for 1.1 million cubic yards removed. Trimming 700,000 cubic yards will make a difference in the aesthetics of what has become a popular hiking and equestrian site, some said.

“For her to craft this compromise is really to her credit and it is a tremendous advance,” Pasadena Mayor Terry Tornek said. “These amendments go a long way in meeting the requests by the city of Pasadena.”

The 5-0 vote comes after seven years of planning the project, 80 public meetings and on-site negotiations that eventually resulted in the changes. The court case forced the county Department of Public Works and Flood Control District to add more restrictions to protect wildlife in Hahamongna and reduce tailpipe emissions from bulldozers and dump trucks.

After going on a hike with Brick in Hahamongna along the Arroyo Seco, Barger, who indicated she believed the county’s plan was over ambitious, decided to meet the environmental groups half-way, with less digging and scraping of habitat.

“I want to make sure we don’t do any more than we need to and we keep within that footprint,” said Barger just before the final vote.

Even with the reduced scope, the $100 million project starting next year will take five years, and will require 400 diesel truck trips per day.

Trucks will take debris to landfills in Irwindale and Sunland, using major thoroughfares and staying off residential streets of Pasadena, La Canada Flintridge and Altadena, said Mark Pestrella, chief of the Department of Public Works.

County engineers say large-scale dredging within the city park is needed to return the nearly 100-year-old dam to full operation. In its current state, mountain runoff may overflow into its spillway during a major storm, potentially inundating the Rose Bowl, Brookside Park and 447 structures in Pasadena, South Pasadena and parts of Los Angeles, according to the county.

The Arroyo Seco Foundation and Pasadena Audubon had endorsed the city alternative. Brick said his group will work with the county to improve plans involving planting native trees and shrubs.

Members of Pasadena Audubon who spoke at Tuesday’s meeting called Barger’s plan a step in the right direction, but predicted destruction of sensitive bird habitat, regardless.

The original project would have left “a 55-foot-deep, bare, steep-sided permanent pit near the dam,” the group said in a statement. Brick said the ditch won’t be as deep or steep with less sediment removed.

Speaking for Pasadena Audubon, Kym Buzdygon said the nesting pair of least bell’s vireo, an endangered bird with a population of only 300 in the United States, may be a fatality.

“If you bulldoze the habitat the vireos are not coming back,” she said at the board meeting.

The 2009 Station Fire blackened 160,000 acres of forest land, including 68 percent of the slopes in the mountains above the dam. Debris from storms sent 1.4 million cubic yards of dirt and rocks down the Arroyo Seco, reducing the capacity of Devil’s Gate Reservoir to safely contain flood waters. Also, the dam remains at risk of becoming clogged and inoperable without the five-year project, the county reported.

In October 2010, the state Division of Safety of Dams recommended removal of sediment behind the Dam and restoring reservoir capacity to minimize flood risk downstream, according to the county staff report.

On Dec. 11, 2014, the two environmental groups challenged the project in court, resulting in a mixed decision — Superior Court Judge James C. Chalfant found the original EIR was deficient, but the judge did not set aside the project.

As a result, the county agreed to use dump trucks built in 2010 or later that comply with federal emission standards.

The county also agreed to give $14 million to the state Department of Fish and Wildlife to help restore 77 acres of coastal sage scrub habitat. The county will protect five special status species living in the dredging zone: the vireo, yellow warbler, southwestern pond turtle, coast range newt and the two-striped garter snake, according to the EIR.

The county will use biologists to help erect fencing to protect nesting birds, including the endangered least bell’s vireo found nesting in the project zone. Also, a major mitigation effort will include capturing birds and other wildlife and relocating them to sections of Hahamongna Park outside the project area.

A related project to pump water from the Arroyo Seco to the Eaton Canyon spreading grounds across town was scrapped. Instead, Barger wants to see more storm water captured and percolated back into the aquifer at the Arroyo Seco Spreading Grounds.

The Los Angeles County Board of Supervisors voted on a scaled-down plan to clear out years of sediment behind the Devil’s Gate Dam in Pasadena. (SGVN/Staff Photo by Walt Mancini/SXCity)




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