The Big One - Earthquakes and the State Water System
The State Water Project delivers fresh drinking water from Oroville Reservoir through the Sacramento / San Joaquin Bay Delta, and onwards to regions throughout the rest of the state. As water travels through the Delta, the conveyance system is vulnerable to a seismic event because the water travels through dirt levees that were intended for farming and were never built to be a seismically reliable drinking water system.
Oroville Reservoir courtesy DWR
Photo courtesy DWR
These Delta levees are very vulnerable and have been breached 163 times since 1900 according to the Department of Water Resources. Numerous major fault lines located near these levees combine together to generate a 98 percent probability of a 6.0 or greater earthquake in the Bay-Delta region over the coming decades, according to the U.S. Geological Service. If a serious levee failure were to happen, the State Water Project could be flooded with saltwater from San Francisco Bay and the system could be inoperable for one to three years.
California Waterfix will modernize the hub of the State Water Project, building new intakes in the northern Delta with seismically reliable pipelines to convey the water underneath the Delta. The two tunnels will be built to modern standards to withstand a major earthquake, and would offer system redundancy so that one tunnel may be shut down to perform maintenance on the other tunnel.
If adopted, California Waterfix will safely and reliably transport critical water supplies to the 25 million people, farms, and business that depend on this water.
View a short video here of a simulated Delta earthquake with levee break scenarios.
Two Water Projects with Seismic Goals:
San Francisco's WSIP and California WaterFix
Did you know that many water systems around California are investing in seismic reliability improvements similar to CA WaterFix? San Francisco's Water System Improvement Program (WSIP) funded $4.8 billion for seismic improvements with a commitment to not expand water supplies for their system via the project.
The San Francisco Public Utilities Commission (SFPUC) delivers 85 percent of its water supplies from the Hetch Hetchy Reservoir in Yosemite National Park. This water is delivered to 2.5 million people throughout the Bay Area, with pipelines that pass over three major seismically active faults. Many portions of the 160-mile water system were aging and in need of seismic upgrades. Voters in the Bay Area passed bond measures authorizing the SFPUC to enact the WSIP, a $4.8 billion project to enhance water system reliability and restore sensitive ecosystems.
Both the WSIP and California WaterFix have similar seismic reliability goals and have been engineered to make each system more reliable while not taking additional water from their respective ecosystems.
Directly east of the WSIP Bay Tunnel Project is the similar seismic retrofit tunnel project proposed by CA WaterFix.
The WSIP project constructed secondary tunnels in parts of its water system (such as building a secondary New Irvington Tunnel) to enhance reliability and provide maintenance opportunities. Having two tunnels provides redundancy during a major earthquake. For example, if one tunnel is impaired, the other can continue service. The WSIP project also built the Bay Tunnel Project, the first tunnel under San Francisco Bay.
Reliable delivery of water is an important priority for water systems in Northern California, Southern California and every part of the state where earthquakes happen. CA WaterFix is all about reliability.
Read the previous issue of California WaterFix Update here.