Four major aqueducts along the Wasatch Front are the heart of a system that ultimately delivers drinking water to more than 2 million people.
A report on these structures details how three of them cross the Wasatch Fault zone and the fourth is in an area of risk for landslides or other ground movement.
In the event of the “Big One,” these aging water delivery systems would fail and be offline for several months, maybe as long as six months, as custom parts from out of state would have to be shipped to Utah.
“We can improve treatment plants or trunk lines, but none of that will do us any good if there is no water in the system,” said Ari Bruening, chief executive officer of Envision Utah.
“I don’t know about you, but if I am without water for six months, I will find an out of state relative to live with. What does that do to our economy if half the state leaves?”
Utah is not alone in its vulnerability. Aging aqueducts across earthquake-prone areas in the West, such as Southern California, are under similar threat.
Three major aqueducts in Southern California supply 50% of the region’s water needs to 19 million people. The aqueducts import water from outside the region and cross the San Andreas Fault.
The failure of these aqueducts, like in Utah, not only pose a threat to the state in which they reside but to the U.S. economy.
In response, a multiagency seismic resiliency task force was created in Southern California to figure out how to tackle the challenges of these independently owned and operated systems.
‘Nothing is OK if we don’t have water’
Here in Utah, Envision Utah worked with the Utah Seismic Safety Commission in that body’s review of vulnerable infrastructure threatened by earthquakes and arrived at a list of priorities.
“As we got into what would happen in an earthquake, there are a lot of things you can tackle, from roads and power and sewer and so on, but the role of water rose to the top,” Bruening said, adding the commission vote on aqueducts being the top priority was unanimous.
“Not only does much of Wasatch Front water come from a great distance through the dams, tunnels and aqueducts of the Central Utah Project, the Provo River Project, and the Weber Basin Project, the vast majority of this water crosses the Wasatch Fault in three major aqueducts as it enters our urban valleys,” the report said.
The report notes that three of the aging aqueducts, Alpine Aqueduct in Utah County, the Salt Lake Aqueduct and the Jordan Aqueduct were built generations ago. The Salt Lake Aqueduct, for example, is 42 miles long and was built in the 1940s and serves 450,000 residents. The next scheduled maintenance on an earthquake vulnerable segment is not slated until 2041, according to the commission’s report.
“These aqueducts are pretty old,” said John Crofts, earthquake program manager for the Utah Division of Emergency Management. In the event of a major earthquake, it is unfathomable the “incalculable the harm it would do,” to the aqueducts, he said.
“If we don’t have water, that is just not OK. Nothing is OK if we don’t have water.”
Jessica Chappell, vice chairwoman of the commission, said not only will the impacts be severe to public health, but to the economy.
“We could be well over three months after a significant earthquake and while buildings and roads may be online, we’re still waiting on water and sewer,” she said. “At what point do citizens of the state decide they could take that job in Boise, St. George or Las Vegas? There is a real risk of long-term impacts to our economy.”
Despite the impact of their loss in an earthquake, Crofts said fixes to the aging aqueducts would be a pretty good return on the state’s investment.
An analysis shows it would take $192 million to implement the fixes, or the cost of three interchanges on Bangerter Highway or what it would take to expand a three-mile section of U.S. 89 in Davis County.
There are already some efforts underway to institute seismic upgrades in a couple of the districts.
At Central Utah Water Conservancy District, the largest district in Utah that depends on Colorado River water, assistant general manager Dave Pitcher said meetings and open houses were held late last year to gather public input on where to relocate and bury a vulnerable segment of the Alpine Aqueduct.
An analysis shows it is at risk of failure from both seismic and nonseismic events, posing an unacceptable risk to the drinking water supply for 1.6 million people in Utah and Salt Lake counties.
Farther north at Weber Basin, general manager Tage Flint said the district has already purchased land and is in the design phase for a parallel aqueduct to its existing infrastructure that is farther away from the fault line.
“It is not an issue that the current aqueduct is in bad condition,” Flint said. “It is in good shape. Anytime you can have two pipelines with the same capacity to carry all the water you need, it ups your survivability.”
The commission, which advises the Utah Legislature, will brief lawmakers on its recommendations for aqueduct fixes this next session, which starts Jan. 18.
In his proposed budget unveiled in December, Gov. Spencer Cox made clear that water conservation projects are a priority — recommending $500 million in spending — and it is also likely building sustainability around key water delivery projects will gain some political momentum.
Keith Koper, chairman of the commission, said talk about the aftermath of a big earthquake and the damage it could inflict on water delivery should get people’s attention.
“If there is a big earthquake it could be devastating. If the water supply were disrupted it would be extremely difficult to recover,” Koper said. “It is a big number for the aqueducts but it is a critical issue — having water.”
Both Crofts and Chappell said the commission has already had active engagement from lawmakers and are hopeful there will be robust discussions when it comes to the vulnerabilities of the aqueducts.
Water infrastructure, however, is not a sexy topic for the public — so the challenge rests with a solid understanding of the risks, the need and how the Wasatch Front water supply for everyone is so compromised.
“These aqueducts are interesting in one way,” Flint said. “They are the arteries on which communities depend everyday, but they are largely out of sight and out of mind. We are very aware of them because we deal with them everyday. But the public is not aware they run all over the Wasatch Front.”