file under:
Environment, Water
Restoring the Central Arroyo Seco Stream
Habitat and Aquatic Life Improved
Claimed by many as the “most celebrated canyon in Southern California,” the Arroyo Seco stream and watershed have been in danger of losing the natural resources that define the area. In 1911, Theodore Roosevelt proclaimed that the Arroyo Seco “…would make one of the greatest parks in the world,” but urbanization and flood control measures have since produced severe negative effects. However, thanks to the efforts of the Arroyo Seco Foundation, the city of Pasadena, and CDM Smith, the beauty and recreational opportunities of this natural treasure have been restored and preserved for generations to come.
“The beauty and recreational opportunities of this natural treasure have been restored and preserved for generations to come.”
As part of an overall city plan to completely naturalize the stream, CDM Smith designed and built the $2.5 million Central Arroyo Seco Stream Restoration Program (CASRP), including improvements to the area’s aquatic habitat, vegetation, trails, and nearby Rose Bowl parking lot. Wendy Katagi, CDM Smith project manager, explains , “This program was supported by the city and driven by the leadership and passion of Tim Brick, managing director of the Arroyo Seco Foundation. An environmentalist and visionary, Tim is an expert on smart water management and greening watersheds,” says Katagi.
No Place Like Home
Roughly 35 years ago, channelization and the creation of Devil’s Gate dam contributed to the elimination of the native fish the Arroyo chub from the Arroyo Seco stream. With no clear passage to migrate or areas to spawn, the chub could not survive. Today, improved stream conditions and water quality have made it possible for the fish to be reintroduced. Scouring holes, resting areas, and spawning areas were constructed from natural materials; backwater pools were created to provide off-channel habitat areas; and weirs were added to stabilize water levels.
The chub, a California “species of concern,” were translocated to the Arroyo Seco stream from the Big Tujunga stream under the direction of the Department of Fish and Game. “The chub are expected to successfully multiply in the Arroyo Seco because of the improved habitat. Eventually, thousands of other fish species compatible with the chub will also be reintroduced to the stream,” explains Katagi.
Pollution Control
Stormwater from the Rose Bowl parking lot flows into the Arroyo Seco, threatening aquatic life with oil, grease, and other pollutants. As part of CASRP, permeable parking places and 10 native plant islands were placed in the lot to treat urban runoff before it enters the stream. In addition, the city of Pasadena provided in-kind contributions of 500 full-capture trash inserts in storm drains surrounding the stream and throughout the city. The devices prevent trash from entering the storm drain system and discharging to the Arroyo Seco.
Community Volunteers Pitch In
CASRP promoted volunteerism and environmental stewardship through more than a dozen community events. The program included educational workshops to teach the public about the area’s habitat, invasive plant species, and water quality, as well as clean-up events attended by hundreds of volunteers. The foundation and CDM Smith worked with the Pasadena Parks and Natural Resources Division to educate young students—who helped plant native trees—about the work being done and its importance. According to Brick, “There has been a staggering response from people all over Southern California—not just Pasadena—to volunteer. We had no idea that the community was so hungry for restoration.”
Lasting Benefits
Prior to the project, trails and slopes surrounding the Arroyo Seco were eroding, affecting water quality and trail widths. The program leveled and stabilized the trails and created stream crossings for pedestrians and equestrians. Educational kiosks and signage were also incorporated. “Some residents told us that they used to be nervous to use these trails, and would stick to the paved areas surrounding the Rose Bowl—we have made a lot of hikers, dog walkers, and bikers very happy,” notes Katagi.
