KEEPING THE WATER FLOWING:
Seismic Resiliency Along the San Andreas Fault
Multi-Agency Collaboration Takes Aim at
Safeguarding Water Delivery
In August 2015, the California Department of Water Resources (DWR), the Los Angeles Department of Water and Power (LADWP), and the
Metropolitan Water District of Southern California (MWD), formed the Seismic Resilience Water Supply Task Force (SRWSTF) to improve the
seismic resilience of imported water supplies to Southern California.
www.ca-nv-awwa.org 21
THE TASK FORCE’S PURPOSE
is to collaborate on studies and
mitigation measures that ad-dress
unique vulnerabilities of
major imported water aque-ducts
crossing the San Andreas Fault. Spe-cific
goals include: 1) revisiting historical
assumptions regarding potential aqueduct
outages due to seismic events, 2) establish-ing
a common understanding about indi-vidual
aqueduct vulnerability assessments,
projected damage scenarios, and planning
assumptions, and 3) identifying opportu-nities
to improve the seismic resilience of
Southern California’s imported water sup-plies
through multi-agency cooperation.
On March 30, 2016, SRWSTF conduct-ed
an Aqueduct Workshop focusing on: a)
potential damage to Southern California’s
imported water aqueducts from a major
seismic event on the southern San Andreas
Fault (SAF), b) identification of regional pri-orities,
and c) potential mitigation options.
Workshop participants were asked to con-sider
preparation for, and response to the
Great Southern California ShakeOut Scenar-io
of a M 7.8. earthquake developed by the
U.S. Geological Survey (USGS) and many
partners. Specifically, they were asked, if all
aqueducts were owned and operated by a
single agency, what steps should be taken
now to mitigate potential damage and what
would the priority of repairs be to most rap-idly
restore imported water deliveries to the
region?
The team concluded that recovery
times would exceed historic planning as-sumptions,
that restoration of partial aque-duct
flows could take at least two months,
and restoration of full aqueduct capacities
could take more than six months.
The findings and recommendations
were significant in that they clearly pro-vided
justification for the three regional
water agencies to continue working to-gether.
The workshop helped develop a
meaningful consensus regarding specific
future actions to better prepare for large
seismic events and that the region would
be best served if the three agencies:
• Move forward with recently identified
mitigation projects on the Colorado
River Los Angeles aqueducts.
• Prioritize additional known vulnera-bilities
on the two aqueducts and the
State Water Project.
• Execute an agreement to allow for a
coordinated response to emergency
events.
• Share resources when responding to
emergency events.
The agencies have developed a five-year
plan to accomplish the identified
goals and additional collaborative
actions such as sharing approaches to
facility vulnerability investigations and
conducting multi-agency emergency
exercises. MWD is seeking board
approval for a project that will implement
the identified mitigation measures for
the Colorado River Aqueduct and has a
draft Memorandum of Understanding
for coordinated response to emergency
events under internal review. LADWP
and DWR are prioritizing known
vulnerabilities on their systems and are
planning to participate in a upcoming
MWD emergency exercise based on a
postulated seismic event. S
Craig Davis (LADWP), David Clark
(MWD) and David Rennie (DWR)