Arroyo Seco Foundation

Out with the Invaders

On September 29, 2018, thirty-three volunteers from the Audubon Center at Debs Park and the Rose Bowl Bruins UCLA Alumni Network contributed 99 volunteer hours to an invasive species removal activity in the upper Arroyo Seco watershed. Volunteers removed approximately 220 cubic feet of eupatory (Ageratina adenophora), cape ivy (Delairea odorata), and blue periwinckle (Vinca major) from a 1.75-acre area of the stream corridor about one half mile upstream of Hahamongna Watershed Park. The City of Pasadena Public Works Department supported this event with tools, waste hauling, and more direct access to the work site.

The work site, located about half a mile north of the JPL Bridge, was heavily disturbed by sediment flows following the Station Fire in 2009. The proliferation of these invasive species has impacted the regeneration of native riparian woodland species including white alder (Alnus rhombifolia), California sycamore (Platanus racemosa), coast live oak (Quercus agrifolia), and holly leaf cherry (Prunus ilicifolia. Several seedlings of each were observed at the work site. During the activity, volunteers also observed two Pacific tree frogs (Pseudacris regilla) and a toe-biter or Giant Water Bug (Family Belostomatidae).

The invasives species eradication was part of ASF's Rainbow Trout Restoration Program. Restoring critical riparian and aquatic habitat is critical to the long-germ success of the program, which has been funded by the National Fish and Wildlife Foundation.

Please see the photos for a group photo and Audubon's event flyer.

Pacific Tree Frog


Working Hard

Cape Ivy


In the Forest