Throughout the state, there are more than 100 active faults that
have produced earthquakes resulting in widespread damage and
deaths. In Southern California alone, since 1933, there have been
23 significant quakes of magnitude 5.9 or greater. The San
Andreas Fault, the major fault line running through California,
is expected to be the source for a major earthquake. It was the
source for the earthquake that leveled San Francisco in 1906.
Water infrastructure is vulnerable to earthquakes:
* In the Sacramento-San Joaquin Delta, man-made levees
dating back to 1850 are identified as at risk when a major
earthquake hits.
* The U.S. Geological Survey (USGS) estimates a magnitude
7.8 temblor on the southern portion of the San Andreas Fault will
cause major damage to infrastructure, including water lines and
dams.
A panel of experts in Southern California also has identified the
following risks as a result of a major earthquake:
* Likely major damage to the main aqueducts bringing water
to Southern California from Northern California and the Colorado
River. Repairs may be hampered due to damaged roads and
large-scale fires.
* In the following days after a major quake, there may be
no water available due to infrastructure breaks and loss of
power. After that, repairs will bring supplies online slowly.
Water districts and agencies have prepared earthquake
preparedness and emergency plans to address the emergency.
Also, groundwater basins will be used as emergency reservoirs to
make up the water shortages when imported supplies are
unavailable.
Seismic work at Castaic Dam’s tower access bridge in Los
Angeles County has reached a milestone, wrapping up a project
on three bridge piers as its owner — the California Department
of Water Resources — works on reducing risk of quake damage at
its water facilities. … The 500-foot-long bridge provides
access for operations and maintenance crews to the structure
that allows releasing water from Castaic Lake. The bridge was
built in 1974 and later retrofitted in 1998 following the
Northridge Earthquake.
The Bureau of Reclamation today announced the completed
contract negotiation between the United States and the Orland
Unit Water Users Association for the repayment of costs
expended for Safety of Dams modifications on Stony Gorge in
Glenn County in Northern California. The contract will
allow the U.S. to recover the costs that were expended to
repair the dam as a result of state-of-the-art changes to
improve seismic loads on the dam.
Despite the pre-Halloween “atmospheric river” that dumped
nearly 8 trillion gallons of rain in Northern and Central
California, reservoirs feeding the Las Virgenes Municipal Water
District saw relatively little precipitation. Local communities
got less than 1 inch. As the state endures a second year
of a drought that’s brought below average snowpack, record high
temperatures and lower than expected runoff, the water district
has put a call out to its 75,000 customers telling them they’ll
have to do more with less.
15-minute DVD that graphically portrays the potential disaster
should a major earthquake hit the Sacramento-San Joaquin Delta.
“Delta Warning” depicts what would happen in the event of an
earthquake registering 6.5 on the Richter scale: 30 levee breaks,
16 flooded islands and a 300 billion gallon intrusion of salt
water from the Bay – the “big gulp” – which would shut down the
State Water Project and Central Valley Project pumping plants.
The 24-page Layperson’s Guide to
Flood Management explains the physical flood control system,
including levees; discusses previous flood events (including the
1997 flooding); explores issues of floodplain management and
development; provides an overview of flood forecasting; and
outlines ongoing flood control projects.
The 24-page Layperson’s Guide to the Delta explores the competing
uses and demands on California’s Sacramento-San Joaquin Delta.
Included in the guide are sections on the history of the Delta,
its role in the state’s water system, and its many complex issues
with sections on water quality, levees, salinity and agricultural
drainage, fish and wildlife, and water distribution.
This issue of Western Water looks at the BDCP and the
Coalition to Support Delta Projects, issues that are aimed at
improving the health and safety of the Delta while solidifying
California’s long-term water supply reliability.
