County “Big Dig” Plan, Which Would Send Thousands of Truck Trips Rumbling Along Local Streets, Looms Large at Arroyo Seco Meeting

The Los Angeles County Flood Control District’s plan to remove more than 2 million cubic yards of dirt from the area behind the Devil’s Gate Dam in Altadena over five years necessitating thousands of dump truck trips through neighborhood streets loomed over a Wednesday evening meeting at the Pasadena Public Library to discuss the restoration of the Arroyo Seco habitat.

“What Does Restoring the Arroyo Mean?,” presented by the Arroyo Seco Foundation (ASF), brought together a group of advocates and experts involved with the restoration of the Hahamongna area, an oasis of native plants and animals, which would be affected and partly destroyed as part of the county’s plan. 

The Foundation was originally founded by Charles Lummis — the first City Editor of the Los Angeles Times, and the City’s first Librarian — and revived in 1989 to continue Lummis’s original vision. Foundation members have since planted several thousand native trees in the Arroyo, participated in and led major Arroyo planning efforts, educated residents about the Arroyo, and worked to restore the Arroyo for future generations, generating over $25 million in funding for investment into the Arroyo Seco Watershed.

Senior Biologist Wendy Katagi first walked the group through the current plans for the restoration of the the Arroyo Seco watershed — a subwatershed of the Los Angeles River Watershed—which stretches from headwaters in the the San Gabriel Mountains to downtown Los Angeles, passing through Pasadena, Altadena, La Cañada-Flintridge, South Pasadena, and Northeast Los Angeles, draining into the L.A. River at the confluence in Lincoln Heights.

Currently, according to the Foundation’s website, the US Army Corps of Engineers is studying a 10 mile reach of the reach of the watershed running north to south from Hahamongna to near Downtown Los Angeles, for habitat restoration opportunities, such as aquatic wetlands, removal of concrete from the flood control channel,as well as a parallel natural channel.

Hydraulic and structural modeling has been completed, and biologists are now performing habitat modeling, according to the Foundation. An overall cost modeling will follow.

The Corps anticipates completing their study, called the “Tentatively Selected Plan,” by July 2016, according to the Arroyo Seco Foundation. The Tentatively Selected Plan will then be critiqued by Corps headquarters in Washington, D.V. in August of this year. The LA County Flood Control District will then coordinate with the Corps to ensure efforts with the County’s Load Reduction Strategy coincide with the Corps’ Study, reported  the Foundation, in its most recent update.

“The future … condition of the Arroyo Seco Watershed is a serious concern to the public and the LACPW (Los Angeles County Public Works),” said the Corps of Engineers in an early 2002 report on restoration efforts.

“The limited and fragmented open space and habitat along the Arroyo Seco corridor, especially in the lower watershed, will result in the continual decline of the environmental and aesthetic quality in the Los Angeles Region,” the report added.

Meanwhile, Nick Hummingbird, manager of the Hahamongna Cooperative Nursery reported Wednesday that his group has already planted 10,000 new plants in the area, as well as helped to restore 200 native plant species. They have also gathered seeds from an additional 50 plant species. 

Aaron Thomas of Northeast Trees, a group founded through mitigation funds from the construction of the Metro Gold Line, also noted that his group has been working to plant trees in and around the watershed area, most notably around the area of the confluence.

But it was the so-called “Big Dig” and its opposition that garnered the most attention during the meeting. Tim Brick, ASF managing director, discussed the group’s campaign and lawsuit against the proposed sediment dredging project. Brick detailed the recent history of dredging in the area, at least since 1994, the last large-scale dredging project in the Hahamongna.

Brick explained that following the 1994 dredging, the 2009 Station Fire created its own huge amount of ash and sediment. The fire was followed by a flood in 2010, and the county’s announcement of the current dredging plan. The final Environmental Impact Report was released in October of 2014, and the sediment dredging plan was planned for September 2015, until the Arroyo Seco Foundation brought a law suit against LA County Public Works to halt the project as it is now proposed.

Brick emphasized that the ASF is not opposed to the principle of dredging the sediment, but believes that a small, more moderate and manageable program is the better alternative. 

A plan approved by the Pasadena City Council in 2014 proposes a long-term agreement with LACFCD for the County to achieve and maintain a capacity in the Hahamongna basin for 2.5 million cubic yards of sediment. In reaching and maintaining this capacity, no more than 220,000 cubic yards would be removed per year, except after unusually large storm events. 

The Pasadena proposal would utilize 120 truck trips per day, as opposed to the 400 truck trips proposed by the County, and would remove 1.1 million cubic yards of dirt, compared to the 2.4 million cubic yards in the County’s plan.

According to the ASF presentation, a sediment capacity of 2.5 million cubic yards will ensure adequate flood protection while minimizing impacts to habitat and recreation activities in Hahamongna Watershed Park and the surrounding communities. 

The Pasadena plan would also only permanently impact 40 acres, with a ten-acre conservation pool, while the County plan would permanently impact, or destroy the habitat in 71 acres and create permanent roads. Both plans would require five years to complete.

Brick took issue with the County’s claim that immediate sediment removal was necessary, showing in a chart that the current level of sediment in the Devil’s Gate dam area was still well below capacity, even with the addition of the sediment from the Station and the 2010 flood. 

Brick’s presentation called the Pasadena Plan a “road map for ongoing, sustainable sediment management” that would reduce neighborhood impacts by 75 percent, create a stable base for habitat, wildlife and recreation, prevent dangerous sediment accumulation while preserving nature, and one that integrates with watershed and ecosystem restoration goals.

The Arroyo Seco Foundation’s lawsuit against the Flood Control District is slated for court hearings in January of 2017.