February 2017

Judge Says: "Whoa, Big Dig!"

On February 14, 2017, the Honorable James C. Chalfant issued a tentative ruling in Arroyo Seco Foundation & Pasadena Audubon Society v. County of Los Angeles finding that the environmental impact report for the Devil's Gate Sediment Removal Project was critically flawed and sending it back for further revisions and review.

ASF and Pasadena Audubon are pleased that Judge Chalfant recognized the severe flaws in the Flood Control District's EIR. "Our goal has always been to reduce the devasting impacts of the County's Big Dig Program, not to stop it," said ASF Managing Director Tim Brick. "We seek a more moderate and sustainable stream and sediment management program that will protect the habitat in Hahamongna as well as our communities."


Hahamongna Native Plant Nursery Sale
Sunday, March 12, 9 am to 4 pm
Continuaton of the Winter Sale

Hahamongna Nursery is now open
on Saturdays and Sundays from 9 am to 4 pm


How Big Was the Recent Storm?

There has been a lot of hype about the recent storm and its volume. People have even been asking if Devil's Gate Dam is safe. Last year it was the El Niño that never came that was used to terrify local residents. This year it's because of the massive exaggeration about the level of rainfall.

There has been significant flooding and mudslides in other areas, but the storm has been relatively minor in the Arroyo Seco. Here are the facts about this last week's intense storm. The rainfall was intense but short lived, as measured by the United States Geological Service stream monitor just above the mouth of the Arroyo. The flow had

been about 10 cubic feet per second (cfs), but shot up on February 17 very rapidly to reach 861 cfs. That's a strong flash flood in the upper watershed. The intensity of the storm, however, did not last very long. By the next day the streamflow had fallen to roughly 70 cfs. Currently it stands at 23 cfs, a solid flow but nowhere near a flood level.

How does the 861 cfs peak rank among stormflows of the past? The second graph, which is based on 104 years of record-keeping, illustrates that that this year's storm (in light green) does not rank very high. The record flows of 1938 and 1969 were ten times larger.

Devil's Gate Dam Tunnel

About 40 feet of water collected behind Devil's Gate Dam after the storm. The Flood Control District has been releasing water through the 13-foot tunnel that goes though the dam to slowly lower the level.

Note that the water coming out of the tunnel on the downside of the dam is very muddy. Releasing water during and after a storm can actually lower the level of sediment in the basin. It will be interesting to see if there is more or less sediment in the basin after the rainy season.

Renew Your ASF Membership Now for 2017!

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Arroyo Seco Calendar

Your guide to special events related to the Arroyo Seco, the Los Angeles River,
the San Gabriel Mountains, and key environmental issues in our region.

Click on the title link to read the event details.

Wednesday, March 1, 4:30 - 5:30 pm

The Arroyo Culture

Saturday, March 4, 9:00am

Devil's Gate Dam Update Tour

Thursday, March 23, 9:30 am

No Big Dig Court Hearing

News of the Arroyo

An achive of news stories about and related to life in the Arroyo Seco.

Click on the title link to read the entire story

Drought finally over in nearly every part of California, scientists sayFebruary 23, 2017 - California's drought is over in most parts of the state, but effects will linger for many years. Los Angeles County still remains in the "abnormally dry" category.
A better plan to shore up Devil’s Gate Dam: EditorialFebruary 17, 2017 - The San Gabriel Valley Newspapers discuss the Oroville Dam situation and local implications, advocating a smaller, slower sediment removal program for Devil's Gate Dam.
Judge rules Devil's Gate Dam environmental report 'deficient' Devil's Gate DamFebruary 16, 2017 - Judge Chalfant's ruling on the County Flood Control District's Big Dam program means that "Los Angeles County Department of Public Works officials will likely have to revise and re-vet their environmental impact report."
Devil’s Gate Dam sediment removal project dealt a blow after environmental report deemed ‘deficient’February 15, 2017 - Judge James Chalfant ruled the County Flood Control District's Environmental Impact Report on their Big Dig program for Hahamongna Watershed Park deficient and set a hearing on March 23 to consider remedies. -
New setback in plan to dredge Devil’s Gate DamFebruary 14, 2017 - KPCC covers Judge James Chalfant's ruling on the County Flood Control District's massive sediment excavation and trucking project for Devil's Gate Dam in Hahamongna.
Time for a new look at flood management in Pasadena’s Arroyo Seco: Guest commentaryJanuary 29, 2017 - LA County Supervisors should take a new look at the County Flood Control District's devastating program for Hahamongna in the Arroyo Seco at the foot of the San Gabriel Mountains.
L.A. to acquire property known as 'crown jewel' in river revitalization strategyJanuary 29, 2017 - The LA City Council took a big step Friday to move forward on the LA River restoration by acquiring the G2 parcel in the east bank of the river in the Glendale Narrows section just north of downtown LA.
Dare to drive California's first freeway from L.A. to PasadenaJanuary 29, 2017 - As part of a list of essential adventures and experiences in the Golden State, Christopher Reynolds offers: Dare to drive the Arroyo Seco Parkway! Most of us crossed that off our bucket list decades ago. -
Green Infrastructure Key to Solving 21st Century Water CrisesJanuary 27, 2017 - Delivering ​water and ​sanitation for ​all in the 21st ​century will ​require a new ​approach - one ​that does not ​solely rely on ​gray solutions, ​but gray in ​combination ​with “​green” ​systems such as ​forests, ​grasslands, and ​wetlands, which ​protect our ​access to clean ​water and are ​more resilient ​to environmental ​change.
Visit these 4 San Gabriel Valley waterfalls in ‘rare form’ after recent rainJanuary 27, 2017 - Here are some scenic waterfalls in the San Gabriel Mountains that are flowing after the long drought.
Pasadena Escapes Significant Rain Damage So Far, Storm and Flood Watch Continues TodayJanuary 23, 2017 - This week's storm has had minimal impacts on Pasadena besides confusing people interested in the Pasadena Half Marathon & 5K.

Arroyo Seco Foundation
Los Angeles River Center, 570 W. Avenue 26 #450, Los Angeles, CA 90065
PO Box 91622, Pasadena, CA 91109
(323) 405-7326 | info@arroyoseco.org

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