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Hahamongna is that 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.

Threats to Hahamongna

It's the most precious enviromental zone in our region, but it's under attack again.

A massive sediment and habitat removal program of the County of Los Angeles threatens to strip the basin of its rare riparian and alluvial scrub habitat

The Sustainable Plan for Hahamongna

Dangers of Diesel


A Strategy to Save Hahamongna


Hahamongna Updates

Hahamongna's Fate: It's Up to You . . . and the County Supervisors

County Flood Issues EIR Revisions

The County Flood Control District has now released their revisions to the Final Environmental Impact Report for their Big Dig mining and trucking operation in Hahamongna. They have made some minor concessions, but the worst parts of their program are still there: 1) its too big; 2) too fast; and 3) too destructive to habitat, our air quality, traffic and neighborhoods.

There is now a 45 day review period which extends from July 24th until September 7th. We urge you to state your views on the revisions and the overall program itself.

The ultimate decision on the fate of Hahamongna will be made by the County Board of Supervisors, which must act to certify that the entire EIR is in compliance with the California Environmental Quality Act (CEQA). This is the time for those who care about Hahamongna to speak with a loud voice telling the Supervisors to Save Hahamongna and ensure that the sediment removal program is reshaped along more sustainable and environmentally-sensitive lines.

Deadline for Comments: September 7, 2017

We're Coming Down to the Final Decision —
Your Action Now is Critical:
Please Support the No Big Dig Lawsuit!

Remaining Steps to Save Hahamongna:

Factsheet  EIR Revisions  Sediment Resources  Contact Supervisors

The Trucks Are Coming! 50,000 a Year!

The Trucks are Coming!!!

150,000 double-bed, diesel belching monsters, clogging streets, creating noise, dust, pollution, destroying precious habitat and severely impacting our neighborhoods

SUPS: Time for a New Look at the Big Dig

Now that there's a new Board of Supervisors who are more progressive and environmentally oriented, it time for them to take a new look at the Flood Control District's devastating plan for Hahamongna and at the unchecked power of the Flood Control District.