For more than 100 years, the Los Angeles Aqueduct has endured earthquakes, flash floods, and dozens of bombing attacks as it winds its way through the canyons and deserts of the eastern Sierra Nevada.
But earlier this month, record storms did the unthinkable when floodwaters undermined a 120-foot-long section of the aqueduct in the Owens Valley, causing its concrete walls to collapse.
“We have lost the aqueduct!” an inspector with the Los Angeles Department of Water and Power told his superiors by cell phone. As he spoke, chocolate-colored runoff and debris undermined the aqueduct just west of Highway 395 and the community of Olancha.
It was the first time in history that the 200-mile aqueduct had ruptured due to extreme weather conditions, threatening the water supply to 4 million taxpayers in Los Angeles.
It was also an indication of how difficult it would be to defend the waterway against the torrential runoff of a winter with near-record snow cover. For weeks, DWP crews had been using heavy equipment and other means to control anticipated spring runoff, but even the aqueduct workers were shocked by the suddenness of the rupture.
Among the first to arrive on the scene that morning of March 10 was a team led by Ben Butler, Senior Water and Reservoir Manager.
“The floodwater came down hard, creating a large, deep pool that pressed against the walls of the aqueduct,” he recalled. “We drove as far as we could, then put on boots and headed for the gap.”
For the next five days, rescuing Los Angeles’ water became the DWP’s top priority as all hell broke loose in the Owens Valley.
Traditionally dry rocky streams and ditches were overflowing; irrigation diversions and culverts were buried in mud with the consistency of peanut butter. At Pleasant Valley Dam, about 8 miles north of the town of Bishop, sediment-laden stormwater was rising over its spillway and into the Owens River at a rate of 1,000 cubic feet per second.
“We were already in an all-hands mode when we found out that the aqueduct was in serious trouble,” said Adam Perez, deputy manager of operations for the aqueduct. “At 3 p.m. that afternoon, we came up with a game plan to prevent further deterioration, repair the gap, and maintain service.”
As an emergency action, the DWP opened spill gates on the aqueduct 25 miles to the north to drain the damaged section and make repairs.
However, those mass launches were not without consequences. The released water flooded ranches in the valley floor, as well as a half-mile stretch of State Highway 136 just south of the Lone Pine community, and moved toward sprawling grounds at Owens Lake, where it caused more issues.
The lake, once navigated by steamboats, evaporated into dusty salt flats after the aqueduct was completed in 1913. In recent years, the DWP has spent $2.5 billion on projects designed to keep harmful particles out for the health of the lake bed into the air.
But as the aqueduct’s inlets flooded the beach, they dissolved alkaline minerals there, creating a large pool of corrosive brine that could ruin some dust-control projects, authorities said.
Overall, it took more than 100 DWP staff working non-stop for almost a week to repair the aqueduct. His work included replacing damaged concrete walls and coating them with a special mix of cement, sand, fibrous material and adhesives that dries faster and harder than conventional concrete.
“It wasn’t easy driving so many boots on the ground in a short period of time in unfavorable conditions,” Perez said. “In the end, the damage did not affect any communities in the area.”
Nodding appreciatively to the load of Sierra snowmelt flowing high and fast through the repaired section of the canal Thursday, he added, “Our crews did a great job.”
Going forward, he said, DWP inspectors will intensify daily patrols of its water systems and dams in the Owens Valley.
However, in the aftermath of the crisis, critics point to the breach and subsequent flooding of the valley floor as signs that the DWP is losing control of its massive and complex water infrastructure amid extreme weather conditions.
A singular feat of civil engineering and deception, the aqueduct has fueled the phenomenal growth of Los Angeles and inspired deep suspicions about the city’s motives that persist to this day in the Owens Valley.
Most of its water is diverted from the Owens River, which flows through a valley that was inhabited for thousands of years by the Paiute Indians before white settlers occupied their land.
In 1905, Los Angeles city agents posing as ranchers and farmers acquired most of the land and water rights in the Owens Valley and construction of the system of tunnels, conduits, and reservoirs began in 1907.
In the early 1920s, tensions were simmering in the area over the city’s continued takeovers. Over a three-year period, the aqueduct was dynamited more than a dozen times.
On September 15, 1976, a dynamite explosion ripped open one of the five entrance gates of the Alabama Hills Aqueduct, spewing 100 million gallons of water onto the valley floor.
Today the talk in local cafes and watering holes is about whether the DWP will be up to the task of controlling the flood levels expected this spring and summer.
Some residents are heartened by the sight of caravans of DWP-owned bulldozers and dump trucks laden with rocks and mud rumbling to and from flooded areas.
“We’ve had a lot of rain, snow and temperature swings lately,” said Dan Siegel, owner of the Merry-go-Round restaurant in Lone Pine. “I think the DWP has been doing a good job when he considers how many places need his equipment and manpower.”
As for predictions of potentially massive flooding when temperatures climb into the 80s and 90s, “we won’t know how much trouble we’re in until we know how fast the snow is melting,” Siegel said.
The DWP system is beginning to show signs of aging. In recent years, several sections of the aqueduct system have been drained to allow for the replacement of cracked and bulging sections of century-old concrete.
Since severe storms began to batter the eastern Sierra region in January, the DWP has been relying on tactical strategies developed during epic rains that ended a five-year drought in 2017.
DWP crews are rushing to clear clogged storm drains, divert excess runoff to grasslands and sage flats, and build berms to divert floodwater away from the small towns that straddle US 395. , including Olancha, Cartago, Lone Pine, Big Pine, and Bishop.
Looking at the snow-capped Sierra peaks to the west, Perez said, “If all that snow falls hot and heavy when the weather warms up, the challenge will be protecting Owens Valley communities from flooding.”
However, there is a silver lining to the situation: For the first time in six years, Los Angeles can expect to receive most of its water from the aqueduct at least until late fall, Perez said.
Just a year ago, at the end of the worst drought in 1,200 years, the aqueduct was delivering about 13% of the city’s water supplies, with much of the rest being purchased from the State Water Project and the Colorado River.