ASF Logo

Arroyo Seco Foundation

News of the Arroyo


Time for a new look at flood management in Pasadena's Arroyo Seco: Guest commentary





<b>January 29, 2017</b> - LA County Supervisors should take a new look at the County Flood Control District's devastating program for Hahamongna in the Arroyo Seco at the foot of the San Gabriel Mountains.


Tim Brick


San Gabriel Valley Newspapers


The spillway at Devilís Gate Dam in Hahamongna Watershed Park in Pasadena. (Photo by Mike Horner/Southern California News Group)

It has been more than two years since the Arroyo Seco Foundation and Pasadena Audubon filed the lawsuit to stop the Big Dig, the Los Angeles County Flood Control Districtís devastating mining and trucking program in Hahamongna Watershed Park. But the debate on how to manage sediment in the Arroyo Seco has been going on for decades. Finally, on Jan. 31, itís going to court.

The county built Devilís Gate Dam almost 100 ago, and since then the dam has trapped a large amount of sand and sediment that would otherwise feed the Arroyo Seco stream, the Los Angeles River and the beaches of Southern California. Rather than managing sediment on an ongoing basis as a maintenance responsibility, Flood Control seems to prefer enormous excavation and trucking projects every 20 years or so, projects that maximize the destruction of precious stream habitat and wildlife corridors as well as the disruption of our communities with traffic, noise, dust and air pollution.

The district has not removed any significant amounts of sediment from the Hahamongna basin since 1994, and then it was only 8 percent of the amount it wants to truck away now. That was right as Pasadena took control of the former county Oak Grove Park and transformed the area into an environmental treasure called Hahamongna Watershed Park.

After the Station Fire in 2009, the need to deal with the sediment buildup in the basin became more urgent, but if Flood Control had managed the sediment as a maintenance responsibility with a slow, steady ongoing program over the years, the sediment would never have reached that level.

Even if it did, the district could have begun a slow, steady program seven years ago that would have pretty much taken care of the sediment buildup by now. In 2010, Flood Control proposed a 1.67 million cubic yard removal project, but the regulators rejected the application, instructing it to come back with a smaller, ongoing program that would reduce impacts to the environment in this rare alluvial canyon. Instead the county, oblivious to that mandate or to overwhelming community input demonstrated during the environmental review process, doubled down and increased the size and destructiveness of the excavation program.

In November 2014, the county supervisors approved the Flood Control Districtís $100 million Big Dig project to remove 2.4 million cubic yards of sand and sediment from Hahamongna Watershed Park Seco and to permanently desecrate 53 acres of rare stream-zone habitat in Southern Californiaís most celebrated canyon. Imagine that: $100 million to truck sand and sediment to distant landfills!

Attorneys representing the Arroyo Seco Foundation and Pasadena Audubon promptly challenged the Flood Control Districtís Environmental Impact Report. Since then, attorneys have done a terrific job of monitoring the environmental permits for the project and of preparing the legal case for a more scientific and integrated approach to sediment and stream management. Meanwhile, Flood Control as been unable to obtain the permits necessary to begin their massive mining and trucking operation. New endangered species have been identified in the basin, and community opposition has remained solidly opposed to the countyís plan.

The Los Angeles Board of Supervisors now is remarkably different from the 2014 board that approved the Big Dig. The old board rubber-stamped Flood Controlís plan to send more than 400 diesel-spewing trucks each day for three to five years into that rare riverbed canyon at the foot of the San Gabriel Mountains.

Soon, a legal challenge to that program will be heard in Los Angeles Superior Court. Regardless of the outcome of that case, however, itís time for the new Board of Supervisors to take a fresh look at the districtís devastating program for Hahamongna Watershed Park. It can stop this environmental travesty and dramatically reduce the enormously destructive impacts of the program. It can assure that the Department of Public Works is accountable to the public and acts as a steward of precious environmental zones.

The countyís extensive system of dams and ditches was built long ago as a series of experiments and pilot projects in the era before environmental review and sensitivity were incorporated into public works projects. It is now time to take a new comprehensive look at these facilities and their impacts and to develop a 21st-century program for sustainable stream and flood management.

ASF aims to restore wild trout in the Arroyo and is working with County Public Works and the Corps of Engineers to restore habitat conditions in this major tributary of the Los Angeles River. Pasadena Audubon is dedicated to protecting endangered birds like the least Bellís vireo and the burrowing owl that have been spotted there. After all, floods and sediment arenít the only considerations for good management of the Arroyo Seco.

The new Board of Supervisors is widely regarded as having a strong environmental focus. Its first action should be a review of the Big Dig and a settlement of the related lawsuit with a program that will protect us from floods and from environmental devastation in Hahamongna and in the surrounding neighborhoods of Pasadena, Altadena and La Canada Flintridge.

Tim Brick is managing director of the Arroyo Seco Foundation and previously served as executive director of the Hahamongna Operating Company.




Arroyo Seco Foundation, 570 W. Avenue 26 #450, Los Angeles, CA 90065-1011
PO Box 91622, Pasadena, CA 91109-1622 (323) 405-7326