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.

Twin Threats to Hahamongna

Athletic Fields

Habitat Destruction

A Strategy to Save Hahamongna

  1. Visit Hahamongna and bring friends and neighbors to share its elegance. It is especially important to bring children to Hahamongna so they can experience it.

  2. Document Hahamongna and the conditions systematically in pictures and words.

  3. Get Educated – The Arroyo Seco Foundation is planning a workshop soon on “The Nature of Hahamonga” to inform people about Hahamongna and its special attributes. Check with the Arroyo Seco website or Save Hahamongna) for news.

  4. Save Hahamongna – The "savehahamongna.org" website has a lot of background about Hahamongna's special values and on the issues involved. It's a good place to stay up to date on issues and developments. Sign up for the news list there to receive updates.

  5. Demand a Full Environmental Review – Now that the County is preparing an Environmental Impact Report on their sediment removal program, it's vital that they consider the full range of impacts and alternatives including stream restoration in the Arroyo. Insist that they chose the alternative that best protects the environment.

  6. Contact Public Officials - Elected officials in Pasadena, La Canada Flintridge and the County of Los Angeles will make vital decisions about the management of natural resources at Hahamongna. Please contact them to express your concerns and to urge them to protect the nature of Hahamongna.

  7. CASO – the Council of Arroyo Seco Organizations has provided a forum for local neighborhood and community-based organizations for ten years. CASO will hold a regular meetings to discuss the sediment management and habitat issues at Hahamongna and how to protect Hahamongna. Representatives of all neighborhood, community and environmental groups are encouraged to attend. Find out more about CASO here - https://www.arroyoseco.org/caso.htm