As drought, global warming and chronic overstressing push the Colorado River to dangerous new lows, water officials are hoping to prevent an earthquake from severing a vital Depression-era aqueduct that now connects millions of Southern Californians to the shrinking river.
Recently, officials at Southern California’s Metropolitan Water District celebrated as crews lowered a section of an earthquake-resistant pipeline into part of the Colorado River’s aqueduct — the 242-mile system of pumps, tunnels, pipelines and open channels that transport water from Lake Havasu to Southern California.
The upgrade is just the latest example of state and federal water managers struggling to maintain a complex and aging water supply system plagued not only by droughts but also by sagging sewers, leaking pipes and the looming threat of wildfires and earthquakes.
The MWD retrofit is part of a $37 million project to ensure the siphon – which crosses the Casa Loma fault line – is protected from deformation or even potential rupture in the event of an earthquake. Officials said it was a significant step towards securing the state’s water future. Without them, the nearly 100-year-old segment of the critical aqueduct could be shifted by up to 13 feet due to seismic activity, they said.
But experts say the project also underscores the plethora of potential disasters that the state’s water managers must consider on an almost daily basis as the system ages and becomes more vulnerable to rapid change.
“It’s a big complex system that cost a lot of money to build and took a lot of time to get into the ground,” said David Sedlak, a professor in the Department of Civil and Environmental Engineering at UC Berkeley. “And so it demands constant attention from us – whether it’s repairing parts of the system that have reached an age where they need loving care and replacement, or addressing newly discovered problems like their vulnerability to earthquakes.”
The final stretch of the Casa Loma project’s earthquake-proof pipeline is due to be laid in the next two weeks, but the area has also been plagued by leaks and creaks for decades. In the late 1960s, about 300 feet of the pipeline had to be replaced after several cracks occurred, officials said.
In addition, an 800-foot section of the pipeline has experienced more than 5 feet of vertical displacement over 84 years as a result of continued “non-seismic settlement” of the ground surface in a process known as subsidence. In California, subsidence is often attributed to overpumping of the state’s groundwater — the water that sits beneath the surface of the earth — because too much pumping can cause the ground to sink and buckle.
MWD chief engineer John Bednarski noted that the Riverside County area around the Casa Loma Siphon is home to many dairies and farming facilities, which typically have deep wells.
“Because of climate change, they just haven’t brought the rainfall here to replenish the aquifer, so they keep pumping and we have to respond to that,” he said.
But it’s far from the only place prone to such problems. Just days after MWD is scheduled to install the final piece of seismic pipe at Casa Loma, the agency will shut down another section of its Colorado River pipeline to conduct emergency leak repairs.
This leak, located along the 36-mile Upper Feeder pipeline, will result in a 15-day ban on outdoor irrigation for more than 4 million people in the area. Residents are being asked to pause showers and conserve supplies whenever possible during the shutdown, officials said.
MWD chief executive and general manager Adel Hagekhalil said the “double whammy” of a Colorado River pipeline shutdown against a backdrop of extremely limited state supplies is one of many reasons for officials to remain proactive when it comes to water diversification in the region goes portfolio.
“We have a great responsibility to build a water system that is earthquake and drought resilient – both in local water supply and storage,” he said. “We can build our system to respond to these challenges, but even if something happens, we can adapt and respond quickly to move water.”
The problems aren’t limited to Southern California either. Subsidence in particular poses a significant threat to water infrastructure in the Central Valley, which is sinking faster than any other part of the state.
Land under a state-administered aqueduct known as the Friant-Kern Canal, which channels water from the Fresno area toward Bakersfield, has dropped about 13 feet since it was completed about 70 years ago. As a result, the carrying capacity of some canal sections was reduced by more than 50%.
Earlier this year, federal, state and local officials gathered to break ground on the first phase of a $500 million project to shore up this sinking channel, which is showing visible cracks and other signs of damage exhibited The project “symbolizes the importance of strong partnerships so we can meet the critical repair needs of our state’s aging water infrastructure,” Karla Nemeth, director of the Department of Water Resources, said at the time.
But while raising duct walls and replacing old segments should help address the immediate problem, a holistic approach is just as important, said Andrew Hamilton, a civil and environmental engineering researcher at Cornell University. Hamilton recently published a study of the Central Valley’s water infrastructure, which found that collaborative approaches among water utilities, irrigation districts and other agencies are needed to create the most resilient system.
“There’s often a lot of interaction between the different components in the system, and so it’s important to understand from a holistic standpoint what the overall impact is of all these different investments that are taking place, rather than looking at them in isolation,” he said.
Hamilton said similar subsidence issues are occurring elsewhere in the state, including along the California Aqueduct and the Delta-Mendota Canal. However, he noted that another California hazard — wildfires — can also create problems for the state’s water utilities, as increased stream flows can lead to increased erosion, flooding and debris.
“It’s sort of ‘multihazard’ – lots of different risks coming together at the same time,” he said. “Which is fascinating from an academic perspective but scary from a managerial perspective.”
In 2017, heavy rains and erosion damaged spillways at the Oroville Dam in Northern California, resulting in the evacuation of more than 180,000 people. Officials had feared the damage could flush a 30-foot wall of water into the communities below, making it one of the worst dam disasters in state history.
Though Oroville has avoided disaster, a study released this month found that global warming has doubled the risk of a catastrophic “megaflood” in California.
Berkeley’s Sedlak said the state’s unique vulnerability to such disasters is all the more reason to keep working toward a more diversified water portfolio, “because when you don’t have to depend on just one water source, you have the ability to bring water from other places to.” to make up for temporary deficits.”
He said Gov. Gavin Newsom’s recently released water supply strategy, as well as President Biden’s infrastructure bill, are both important steps in the right direction. Biden’s package provides the Bureau of Reclamation with $8.3 billion for water infrastructure projects, including $310 million to combat mega-droughts in the west.
But Sedlak also remembered when former Gov. Pat Brown funded a $1.75 billion water initiative in 1959 that eventually became the State Water Project, which provides water to more than 23 million Californians today. That initial investment would be approximately $18 billion today. He said there was a growing consensus that it was time to move back towards that level of investment, especially since so much has changed since then.
“We got some things right when we extrapolated the number of people living in California, but we didn’t anticipate what the climate would do, and we may not have understood how vulnerable our water systems are to natural hazards like earthquakes and floods,” he said Sedlak. “And now it’s time to make another of those big investments to protect our water systems — not just from drought, but from these other aspects that threaten them.”
https://www.latimes.com/environment/story/2022-08-23/california-water-supply-shrinking-mwd-earthquake-leaks As water supply shrinks, MWD guards against earthquake leaks