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“You would have to build a desalination plant every four miles along the coast to replace the water we import. That isn’t an environmentally or economically feasible solution. We must maintain the reliability of our imported supplies.”
—Stephen Arakawa, manager of Bay-Delta initiatives
Lifeblood of the Southwest
Since Metropolitan’s first CRA deliveries in 1941, water from the Colorado River has helped transform Southern California into the thriving region it is today. The river also sustains people, farms, businesses, tribal nations, and wildlife across six other states and Mexico. But while demands for Colorado River water have grown, supplies from the river have not. The resulting imbalance will likely grow as the climate warms, reducing run-off in the river’s watershed. This is the latest challenge in the enduring struggle to share the Colorado River among the 40 million people and 5 million acres of farmland that rely on it.
A New Era of Sustainability
For the past two decades, Metropolitan has been committed to increasing the sustainability of the Colorado River by building partnerships inside and outside California to develop creative conservation and storage programs based on collaboration, not conflict. The agreements and trust forged provide a critical foundation as water agencies across the west negotiate the next steps needed to address the river’s imbalance.
Building the Colorado River Aqueduct
Originally conceived by William Mulholland and designed by Metropolitan’s first Chief Engineer Frank Weymouth, the Colorado River Aqueduct was the largest public works project built in Southern California during the Great Depression. Over seven years, 35,000 people toiled across the desert to construct the engineering feat.
State Water Project:
Delivering Sierra Supplies
Southern California’s other main source of water — about 30 percent of the region’s supply — comes from the Northern Sierra. It is delivered here through the system of reservoirs and aqueducts known as the State Water Project, the largest state-built water and power system in the nation. The water collects in the Feather River, passes through Lake Oroville and weaves its way through the Sacramento-San Joaquin Delta before entering the 444-mile long California Aqueduct to Southern California. Along the way, the State Water Project provides a critical water supply to more than 27 million Californians from the Bay Area to San Diego and farmland that produces nearly half of the nation’s fruits and vegetables.
With several faults running through the region, the U.S. Geological Survey estimates there is a 72 percent chance of a magnitude 6.7 earthquake hitting the region in next 30 years. Such an event could cause widespread failures along the 1,100 miles of levees that surround Delta islands, allowing seawater to rush in and could render the freshwater that travels between the levees undrinkable for months, even years.
Sea Level Rise
Rising sea levels will not only put more pressure on the Delta’s dirt levees, they will push seawater further into the Delta, impacting water quality, and threatening the intakes that draw water out of the Delta and into the California Aqueduct, which sit only a few feet above sea level.
In the 1850s, the Delta was transformed from marshland to farmland, using levees to keep water back. The process exposed peat soils, which are rapidly vaporizing, causing the land levels to drop and turning the islands into bowls entirely dependent on the levees. As subsidence continues, water pressure on the levees increases, putting them at greater risk of collapse, which would draw seawater toward the Delta’s freshwater resources.
Various endangered species call the Delta home. Regulators’ efforts to protect these species have largely focused on cutting back water exports through the State Water Project, though numerous scientific panels have attributed the decline in the Delta’s ecosystem health to various causes. Over the past three decades, export pumping capability from the Delta has been reduced by more than 2 million acre-feet a year.
Balancing Ecosystem Health, Water Reliability and Home
The Sacramento-San Joaquin Delta is unlike any other place in California. Along with being the hub of the state’s water delivery system, the estuary is home to more than 300 species of wildlife – 29 of which are threatened or endangered, dozens of historical communities and hundreds of thousands of acres of farmland. The fertile peat soil of its islands annually produces $700 million in agricultural crops and its ecosystem supports the commercial salmon industry on the West Coast. The Delta is all at once an element of water infrastructure, a critical ecosystem, a statewide economic engine, and home to 500,000 people. Balancing those identities is the challenge of regulators, water managers, biologists and others.
How much water can be pumped out of the Delta for delivery south to cities and farms every year depends not only on the amount of snow and rain in the Sierra Mountains, but also on the condition of the Delta’s ecosystem and fisheries. For three decades, regulators have increasingly restricted deliveries in an effort to protect endangered species in the Delta, including the Delta smelt. Metropolitan understands that water supply reliability cannot improve without also improving the health of the Delta’s fragile ecosystem.
The Delta Conveyance Project is one part of the solution to help improve water supply reliability. But that alone won’t fix the Delta. Nor will simply releasing more water into the estuary. The Delta was once a vast marshland covered with tules and teaming with wildlife. In the mid-1800s, settlers built levees to drain and reclaim the land and today about 95 percent of the original wetlands and floodplains are gone. In this highly altered environment, non-native species have thrived, over-running native species. Striped bass, Asian clams and many other invaders, large and small, are either eating the native populations or the foods on which they rely.
Addressing these environmental challenges will take science-backed solutions, solutions that Metropolitan is helping research, in collaboration with state and federal agencies. It also will take partnerships with all the diverse interests in the Delta.
Saving for a Not-So-Rainy Day: Exchanges, Transfers & Water Banking
California has always had highly variable weather – swinging from very dry years to very wet ones. As the climate changes, those swings are expected to become even more extreme, which means greater fluctuation in the water resources Metropolitan imports. To ensure Southern California has reliable water supplies, regardless of these swings, Metropolitan has made significant investments in storage. We’ve increased our storage capacity by 13 times since 1990, so when there is a very wet year in the Sierra or Colorado River Basin, we can store water for use in dry years. Some of that storage increase has come through investments in surface reservoirs, like Diamond Valley Lake and Lake Mead, through the Intentionally Created Surplus program. But equally important is the storage capacity Metropolitan has developed through partnerships with water agencies across California for groundwater banking and exchanges.
Other Water Transfers & Agreements
Metropolitan has developed other partnerships and programs to improve the reliability of imported supplies. This includes direct water transfers and exchanges, in which water is directly purchased in dry years, or exchanged for more water in wet years. Metropolitan’s portfolio includes such agreements with state and federal water agencies, water districts and individuals. On the Colorado River, Metropolitan also has developed specialized conservation programs in which Metropolitan invests in agricultural conservation and receives the conserved water.