Hahamongna is the rare spot in the Arroyo Seco at the foot of the San Gabriel Mountains where the mountainous watershed meets the urban plain. Periodically floods roar into this basin. Bounded on the north by the mountains and Jet Propulsion Laboratory and on the south by Devil's Gate Dam, Hahamongna contains five unique habitat zones that only exist in alluvial canyons near the mountains. Most sites like this in Southern California have been destroyed.

Don't let Hahamongna go the way of other lost environmental treasures in Southern California.

The Meaning of Hahamongna

The original settlers of the region were sometimes called the Hahamongna Indians. The word means "Flowing Waters, Fruitful Valley" in the native Tongva language.

Draft Environmental Impact Report Comments

Here are some of the comments that have been submitted by individuals and organizations concerned about the sediment removal project for the Hahamongna/Devil's Gate Basin. These comments will give you a sense of the topics that were addressed in the critique of the Draft Environmental Impact Report.

Now the LA County Flood Control District will review and respond to the comments before they prepare the final project description and Environmental Impact Report. That should take several months. The Flood Control District's goal is to begin excavation and trucking in the Fall of 2015, but their program must be approved by the County Board of Supervisors. That is where efforts to Save Hahamongna now should be addressed.


Hugh Bowles Christle Balvin Arroyo Seco Foundation
Rody Stephenson Marnie Gaede Pasadena Audubon Society
DB Sediments Altadena HeritageASF WPRA
Dianne Patrizzi Michael LongSM Mountains Conservancy
Linda Klibanow Friends of LA RiverCity of Pasadena
Pasadena EAC Friends of HahamongnaMarietta Kruells
Peter Kalmus William ChristianR. Klemm & L. Newlin
Robert Staehle Rebecca Latta Sierra Club Pasadena
Marcus Klemm Ross Heckmann Lori Paul
US Forest Service David Doody Kathi Ellsworth
Lisa Frazier Kiley Akers Tom Sawyer Camps

We encourage individuals and organizations to share your comments. Please send a copy to savehahamongna@arroyoseco.org