Tim Brick

Managing Director, Arroyo Seco Foundation

Standard Equipment Until 1956

Now we recycle . . .

That’s sustainability.

Now we have 1.2

gallon toilets

That’s sustainability

We used to throw away our waste water

Now we recycle more than 350,000

acre feet a year.

That’s sustainability.

But why do we still treat storm water and sediment as waste products???

Six hundred thousand acre feet of storm water each

years flows to the ocean from Los Angeles County

• It provides habitat for fish

and aquatic species

• It nourishes rivers and

beaches

• It fills our valleys and the

coastal plain

• It can be used for

construction purposes

Rivers don’t just transport water. A key function is to transport sediment.

It’s time to take a new look at how we

manage sediment and storm water.

It’s time to stop starving the streams

and beaches of Southern California.

- Make Room for the River

The dramatic geology of

the Los Angeles Basin

The Transverse Range

Alluvial Valleys

Steep erosion-prone

mountains ringing a

dense urban area

These rapidly rising

“teenage” mountains are

rushing to get to Long

Beach . . . in geologic time

We’ve crowded the foothills

We’ve paved our

communities

• Homes and business have

encroached on the floodplain

• We put out streams and

rivers in a concrete strait

jacket to speed the flow of

storm water to the ocean

Driven by the promises of development and imported water

• And neither is

sediment

• But the Sediment

Buildup Is

Have Human Efforts Aggravated the Flood Threat???

The Flood

of 1914

• A watershed

• A canyon

• A stream

• A tributary of LA River

• A transportation corridor

• A parkway

• A cultural haven

• Communities united

. . . The most celebrated canyon in Southern California

Hahamongna is the

vital link

between the Upper

and Lower Watershed .

. .

between the mountains

and the city

Gateway to the

Raymond Basin

Hahamongna –

Total Sediment To Be Removed

(Next 20 Years)

• 14 Dams

• 162 Debris Basins

82+ Million Cubic Yards

Sediment Placement Site Capacity - 11.6

Million Cubic Yards

Cost per cubic yard: $30-60

Total Cost: $3-5 Billion

The Current Program

Devil’s Gate Dam

The first of the

LA County flood

control dams

built in 1920 for

flood protection

and water

conservation

162 Sediment Basins

• All of these facilities were developed before NEPA, CEQA, etc.

• There has never been a thorough review conducted on their environmental

impacts

Sediment, water

and debris move

down gradient

through the

watershed towards

the ocean, creating

dynamic riverine

and riparian habitat

and replenishing

beaches along the

way.

The Natural Process

Restoring the Arroyo chub

• We developed the floodplains, alluvial fans, and foothills with industry

and housing.

• We installed engineered solutions such as flood control dams and debris

basins and channelized runoff to prevent property loss and damage.

• We’ve broken the hydrologic cycle precluding the movement of materials

and nutrients out of the upper watershed towards beaches.

How It Happens Today – Thwarted Natural Processes

• Rain Barrels

• Rain Gardens

• On-site Retention

• Permeable Pavement

• Unpaving

How many tons

of sand are lost

to the beaches

each year???

“And it never failed that

during the dry years the

people forgot about the

rich years, and during the

wet years they lost all

memory of the dry years.

It was always that way. “

John Steinbeck

The current system of sediment management in Southern California is economically and environmentally unsustainable

It will:

• cost $3-5 billion in the next 20 years

• aggravate human health risks (heavy equipment emissions, noise,

traffic, dust, precludes natural flushing events)

• rob downstream landscapes and ecosystems of their essential

building blocks (fine sediments, sands, gravel, nutrients, etc.)

And it won’t solve the problem

TIME FOR A CHANGE IN PARADIGM!

Developing a Sustainable Integrated Sediment Management Program

• Review the effectiveness and

viability of flood control

methods

• Review the environmental

impacts of the dams and

ditches approach

• Conduct educational outreach

to the public to improve

understanding about natural

processes.

TIME FOR A CHANGE IN PARADIGM!

Developing a Sustainable Integrated Sediment Management Program

• Pursue sediment management

options that safely mimic natural

processes from the top of the

watershed to the bottom

(sluicing, stream and floodplain

restoration, and others).

• Promote SMART development

and re-development

• Landuse regulations (green

buffers, density, proximity to

wildlands, defensible space,

distance from geologic

hazards)

• Mandate low-impact/Green

building design

What You Can Do: • Get Informed • Support River Restoration • Visit Hahamongna • Talk to Local Officials • Subscribe to Arroyo_Seco_News • Support the Arroyo Seco Foundation & Save Hahamongna

Tim Brick

Arroyo Seco Foundation - http://www.arroyoseco.org

Save Hahamongna - http://www.savehahamongna.org