An unfinished study to restore the part-natural/part-channelized Arroyo Seco stream in western San Gabriel Valley is back, a sign that efforts to return native fish, remove concrete barriers and add bikeways along its banks could be realized.
The Los Angeles County Board of Supervisors voted 5-0 to direct the public works department and the county flood control district to complete a study started in 2005 by the U.S. Army Corps of Engineers but abruptly halted in 2017 for lack of funding.
The county will terminate the contract with the Army Corps and redirect the $2.5 million of funding approved by the board in 2017 to cover the cost of completing the study and planning efforts, according to the motion.
While the 22-mile-long river meanders through the Angeles National Forest, Altadena, Pasadena, La Cañada Flintridge, South Pasadena and Los Angeles until it joins the L.A. River near Dodger Stadium, the study will focus on a 9-mile stretch downstream from Devil’s Gate Dam in northwest Pasadena to the L.A. River confluence.
“This study is crucial to the future of the Arroyo Seco and its neighboring communities,” Supervisor Kathryn Barger said in a prepared statement. “Once completed, the study’s results will be a blueprint that guides our county’s efforts to both restore the tributary’s ecosystem while enhancing flood protection to the Los Angeles County residents who rely on it.”
The Arroyo Seco Ecosystem Restoration Feasibility Study and Multi-use Project Implementation Plan will be a partnership between county agencies, the local water district and local cities and communities to determine what projects are feasible. According to emailed responses from county public works, the goals of the study include:
• Determine how much of the Arroyo Seco ecosystem would be restored, which may include removing cobblestones and concrete “without compromising flood protection.”
• Develop conceptual designs for projects, such as “greenways and bikeways.”
• Examine the Flint Wash and the downstream section of the Arroyo Seco for possible connectivity for a half-mile buffer on each side of the channel.
• Restore habitat for fish and other native species.
• Look for additional water conservation possibilities to put more water into the Raymond Basin, which is a source of drinking water for nearby cities and communities.
The Arroyo Seco river meanders through a portion of west Pasadena. The Arroyo Seco riverway was supposed to be studied for restoration of habitat and water savings. However, that study from the U.S. Army Corps of Engineers never got completed and the agency has since abandoned the project after 19 years. The Los Angeles County Board of Supervisors voted to restart the study on Wednesday, March 6, 2024. (File photo by Walt Mancini/SCNG)
The Arroyo Seco Foundation and the Stewards of the Arroyo Seco have been advocating for stream bed restoration. The groups also want to restore rainbow trout to the stream.
Studies have been done on reintroducing Southern California Steelhead, a salmon-like species that between 1850 and 1940 attracted fisherman from across the country to the San Gabriel, Los Angeles and Arroyo Seco rivers.
One of the places where the public can see the Arroyo Seco’s waters is at the Hahamongna Watershed Park between Pasadena and La Cañada Flintridge. The cleanout of the Devil’s Gate Dam at the park came after a decade of lawsuits from environmental groups who said dredging could cause irreparable harm to the river and the naturalized areas of the park.
People who stroll beneath the Colorado Street Bridge and the 134 Freeway bridge can see the natural stream. But signage is lacking and often it gets missed by the general public.
Laura Solomon, former president and conservation chair of the Pasadena Audubon Society, a group that sued to reduce the scope of the dam clean-out project, said on Tuesday, March 5 that she hopes the study will lead to restoration of the river where possible — but also bring more attention to a river that runs almost invisible between several urbanized areas.
“Most people who live in that area don’t know there is a river there,” she said. “The river is disconnected from us, both physically and psychologically.”
Related links
Is re-introducing steelhead trout into the Arroyo Seco another fish tale?
Concerns about Hahamongna Watershed Park habitat, truck-related air pollution raised with start of Devil’s Gate Dam clean-out
California Art Club: Arroyo Seco culture never goes out of style
Arroyo Trail project gets a $500,000 boost
The Arroyo Seco was once snubbed for money for local restoration projects. That could soon be fixed.