[env-trinity] California's Levees Are in Sorry Shape

[Josh Allen]

California's Levees Are in Sorry Shape


http://news.yahoo.com/s/latimests/20050919/ts_latimes/californiasleveesa
reinsorryshape

 

LA Times 

 

By Bettina Boxall Times Staff Writer Mon Sep 19, 7:55 AM ET

 

The threat is well known. A big quake rumbles across the Sacramento-San
Joaquin Delta, knocking out dozens of the primitive levees that guard
the state's main water crossroads. A key source of water for nearly two
out of three Californians and the nation's biggest fruit and vegetable
garden is shut down for months, maybe even a year or two.

ADVERTISEMENT

 

Can the state avert such a scenario?

 

The watery calamity that befell New Orleans has highlighted the sorry
state of delta levees, prompting calls from Gov. Arnold Schwarzenegger
and California congressional leaders for federal money for levee
repairs.

 

The delta's vulnerabilities have also prompted some experts to dust off
an idea they believe might be more practical: building a canal that
would route water around the delta to agricultural and urban consumers
in Central and Southern California. For though it may be technically
possible to armor the delta, many experts doubt it is economically
feasible.

 

Schwarzenegger last week asked the federal government for $90 million to
improve some of the most critical levees in the delta and the Central
Valley. But that is a fraction of the $1.3 billion in repairs officials
say it will take just to bring the delta levee system up to basic
standards. And that would do little to protect it from earthquake
damage. The state Department of Water Resources can't even say how many
billions more it would cost to do the seismic work.

 

"To make them basically earthquake-proof, you would probably have to
start over with a brand-new levee system," said Les Harder, acting
deputy director of the department and an engineer who helped put
together a 2000 state analysis of the delta's seismic risk. "I think
it's going to be unlikely we would ever make the whole delta today
earthquake-proof."

 

That - coupled with projections of rising sea levels that would stress
the fragile levee system even without a major quake or flood - is
reviving talk of a politically charged alternative to delta water
shipments: the Peripheral Canal. Rejected by California voters in 1982,
the canal would have drawn water from the Sacramento River and carried
it around the delta to federal and state aqueducts supplying the Central
Valley and the Southland.

 

"The idea that you can fix this so that [massive earthquake failure]
won't happen is nonsense," said B.J. Miller, an environmental
engineering consultant who represents some of the Central Valley's
largest irrigation districts. "You can't dig out the peat soil the
levees are resting on. There is no economic way to do that.

 

"Everybody knows what the solution is," he said. "Build a canal around
the delta."

 

The Peripheral Canal died largely because of fears that it would become
a giant straw through which Southern California could suck more of the
north's water. Though the concept remains highly controversial, Miller
is not the only one raising it. Former Interior Secretary Bruce Babbitt
mentioned it recently at a hearing on the CalFed program he helped set
up to improve water delivery from the delta. And even some
environmentalists are broaching the idea of a smaller pipeline around
the delta that would ferry some - but not too much - water south.

 

Overall, the delta levee system is in far worse shape than the levees
that so dramatically failed in New Orleans. They have collapsed for no
apparent reason in good weather. Dozens could fall apart if a major
earthquake or flood were to strike, not only imperiling water supplies
but also flooding thousands of acres of farmland as well as highways and
railroads that cross the delta.

 

And though the more than 400,000 people who live in the delta reside
mostly on its edge rather than its more flood-prone interior, growth is
encroaching, bringing more people closer to the levee system.

 

The threat of an earthquake is by no means the only concern. There is a
growing recognition that given rising sea levels, an inadequate levee
system, natural disasters and the ongoing subsidence of delta islands,
the delta is not going to stay the same.

 

"There is a very strong likelihood that the delta as we know it today is
not sustainable over the long term," Harder said. "We're going to have
to take a look at what we need most and where."

 

Change has been a constant in the delta since Gold Rush settlers started
draining and dredging the vast tidal marsh created thousands of years
ago by the confluence of two of the state's biggest rivers, the
Sacramento and the San Joaquin, as they flowed into San Francisco Bay.

 

Using shovels and wheelbarrows, laborers began building what became a
1,100-mile maze of earthen levees that keeps the water out of the dozens
of islands that were planted with crops after they rose from the drained
marshland.

 

The drainage and farming have turned the delta, which is bigger than
Orange County, into California's Holland, making for a constant battle
between land and the more than 700 miles of waterways that wreathe the
islands.

 

Cultivation has broken down the deep peat soils, causing them to blow
away and oxidize, turning to gas. Through soil loss, the islands sink
ever lower. Some areas are now as much as 20 to 30 feet below sea level.

 

The subsidence probably will be accentuated by an expected rise in sea
level tied to global warming. Scientists say the ocean off California
could rise roughly a foot over the next 50 years and perhaps as much as
3 feet over the next 100 years.

 

As the land sank during the past century, the levees got higher. But
they weren't built up according to sophisticated engineering standards.
Mechanical dredges simply scooped up the muck from the adjoining sloughs
and tossed it on top of the old berms. Beneath the levees lie loose sand
and silt that can liquefy in an earthquake.

 

Of the roughly 1,100 miles of delta levees, 385 are maintained by
federal and state agencies and are in somewhat better shape than the
rest, which are overseen by small delta reclamation districts. In
general, however, experts say the levee system is a disaster in the
making.

 

Concern for the levees was sharpened with the recent prediction by a
pair of UC Davis scientists that there is a two-in-three chance that a
major earthquake or flood will hit the delta in the next 50 years,
causing widespread levee failure.

 

"New Orleans lost the battle with the inevitable, and we will suffer the
same fate in some form here in California," said geologist Jeffrey
Mount, one of the Davis researchers.

 

Multiple levee breaks could draw San Francisco Bay's salt water toward
the enormous federal and state pumps that siphon water from the south
delta and send it to the cities of Southern California and millions of
acres of San Joaquin Valley cropland.

 

If that happened, water managers would have to shut the pumps down. For
how long would depend on where and when the levee breaks occurred.

 

Breaches in levees in the western delta, near the bay, would let more
salt water in. If levees collapsed in the summer, agencies would either
have to release a rush of water from upstream reservoirs to flush out
the system or wait until the following spring, when high natural flows
would do the flushing for them.

 

Massive levee failure could easily shut down delta water exports for
months, and, in a worst case, for a year or two. "That's one of the
scenarios they're looking at," said David Mraz, delta levees program
manager for the state water department.

 

Over the last three decades, the state has spent $210 million on delta
levees. The Army Corps of Engineers has spent additional millions on
repairs. Last year's reauthorization of CalFed included $90 million in
federal funding for levee repairs. But none of that has been
appropriated, and total CalFed levee spending has lagged behind
projections. Moreover, the program has yet to adopt a promised fee
system under which delta users would help pay for projects they benefit
from, such as levee work.

 

"There have been a lot of improvements of levee sections. [But] nothing
has yet happened in a meaningful way to reduce the seismic risk, and
that is a Damocles sword for California," said Ray Seed, a professor of
civil engineering at UC Berkeley who has been evaluating the delta levee
system for the last 20 years. "There are lots of people who know how to
fix it. The issue is it's too expensive."

 

Even if it costs too much to seismically reinforce all 800 miles of
levees that are the most critical to maintaining water quality, Seed
said selected levees could be upgraded. He suggested there are simple,
relatively inexpensive things that could be done to speed repairs when
disaster strikes. The state could stockpile the big rocks needed to plug
holes and store on islands the plastic sheeting and sandbags that can
slow erosion after a levee break.

 

Other proposals include taking islands out of farming to slow the
subsidence, flooding some islands with fresh water to combat a saltwater
intrusion during levee failure and erecting barriers that would force
fresh water toward the pumps in the event of flooding.

 

The state has begun a two-year, $6-million analysis of risk to delta
levees that will include ways of dealing with a major saltwater
intrusion to try to avoid a long shutdown in water shipments.

 

In the meantime, some politicians are looking warily at another delta
trend: creeping urbanization. Though most of the delta's 738,000 acres
are farmed, some of California's fastest-growing areas are pushing into
delta lowlands.

 

Symbolic of that growth is the little town of Lathrop, on the delta's
southeastern perimeter. It plans to expand from 12,000 to 80,000
residents over the next 25 years. About 35,000 of those newcomers would
move into a master-planned community the town has approved for a
now-empty delta island known as the Stewart Tract.

 

Town officials say they will require the developers to pay for levee
construction that will guard against a 200-year flood. But critics say
that could just push floodwaters elsewhere.

 

"I am very concerned about the urbanization of the delta," said
Assemblywoman Lois Wolk, a Davis Democrat who has been pushing
legislation - thus far unsuccessfully - to give the state Delta
Protection Commission more muscle to restrict delta growth.

 

"For me, it's part of a larger issue which I believe has become very
clear with what's happened in Louisiana. That is the foolhardiness of
building in a flood plain. We continue to do that and ... we need to
have a statewide approach to restricting that growth. If local
government won't do it, then the state has to do it."

 

More than the delta, the Central Valley is seeing thousands of houses
sprout in areas that have flooded in recent decades. Those areas are
protected by a river levee system that is also in need of extensive
repairs, although it is generally thought to be in better shape than the
delta's aging system.

 

Pointing to new development in Lathrop, as well as north of the delta
near Sacramento and in Sutter County, Wolk said: "All of these are built
in areas that should have remained in agriculture. It should be expected
that there will be a flood. You simply can't make the levees strong
enough."

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