California Storm Weather News: Live Updates

LOS ANGELES — A century ago, Los Angeles built what is still widely considered one of the most sophisticated urban flood control systems in the world, designed to contain water from major Pacific storms like those that recently hit the state.

After a series of rains last week dumped up to nine inches of rain on the San Gabriel Mountains, about 8.4 billion gallons were held back behind 14 large dams, lessening flooding and building up valuable water reserves for the cooler months. summer droughts ahead.

But in a state grappling with a crippling multi-year drought, much larger flows of water – estimated to be in the tens of billions of gallons – have in recent days flown straight into the Pacific Ocean, a devastating conundrum for a state whose future depends on keeping in check. any drop you can.

The era of building large dams is long gone, largely due to the multifaceted environmental wars California is fighting, and the county has been slow to embrace alternatives. Most of the roughly $1 billion raised from Los Angeles County taxpayers over the last four years to store more water has gone unspent.

Now the county is embarking on a radical and risky experiment to see if it can increase supply in a different way: a $300 million-a-year program that would build hundreds of small water catchment projects over the next 30 to 50 years that could eventually hold as much water as mountain dams.

“It’s audacious what we’re proposing, and it’s huge,” said Mark Pestrella, executive director of the Los Angeles County Public Works.

Trees submerged in the Los Angeles River during flooding in Long Beach on Tuesday.
People walk through puddles after heavy rain in Santa Monica.

The urgency of the situation became apparent with the series of atmospheric rivers that have killed at least 19 people since late December. On Friday, rain from another round of storms began to hit parts of Northern California, with a new forecast of waterlogging across the state for Saturday. Meteorologists also predicted heavy snow and strong gusts of wind in the Sierra Nevada.

Some hydrology experts say the new green approach to capturing more southern California rainfall will be expensive and may yield less than expected. They said the region might also need some improvements to traditional heavy infrastructure, also under study, to capture more water from the mountain.

The program is a reflection of the desperate need for new sources of water in a state that has long since exhausted most of its easy supplies, leaving difficult choices that will affect future lifestyles, landscapes, the economy and public health.

The drought of recent years has left depleted reservoirs across the state, scorched forests, abandoned farmland, brown urban lawns, arid ski slopes and disappearing lakes. The Crisis on the Colorado River raises concerns.

After years of deadly drought, images of floodwaters rushing into the ocean as people watch helplessly has been a cruel irony. California enjoyed abundant water long after the Gold Rush of 1849 sent easterners to the state. But continued population growth, the rise of the country’s largest agricultural industry, ever-tightening environmental regulations and now climate change are leaving less and less slack in the system.

Capturing water in extreme events like this year’s is a colossal engineering, environmental and financial challenge, experts say. Even with the planned improvements, water supply will be tighter for the main users: the environment, the population and agriculture.

“Everybody is going to miss something,” said Jay Lund, director of the Watershed Science Center at the University of California, Davis, and a member of the National Academy of Engineering. Mr. Lund estimates that up to 25 percent of agricultural land could fail to produce.

Morris Dam in Azusa, Calif., on Wednesday.

Getting more unclaimed water from rivers may not be easy, as nearly all of it is dedicated to supporting plant and wildlife habitat, as required by regulations and court orders, he said. The state’s uncollected water is found in two main areas: 65% of it is in the wild and scenic rivers of the North Shore, and another 30% flows from the Sacramento Delta.

The rest of the water, 40% to 70% of all state reservoir and groundwater, depending on the precipitation in a given year, is mainly used by agriculture and cities.

Proposals to build a water diversion tunnel in the delta that would help maintain Southern California’s water supply have been debated for four decades, and its fate remains uncertain. Governor Gavin Newsom supported a scaled-down plan.

Until last month, California’s main reservoirs in the Sierra Nevada were well below normal levels, but by Thursday the gap had narrowed significantly. Some are now above average, although Shasta Dam, the largest, is still at 72% of its average and Oroville Dam, the second largest, is at 90%.

Storm management is labor intensive and requires expert intervention. Take, for example, the Los Angeles River, which keeps teams moving at all times during heavy rains.

An operations center at the Alhambra, made up of so-called storm chiefs, monitors dam levels and constantly adjusts discharges to prevent flooding. Mountain dam maintainers are alert for any problems, ready to manually actuate valves in heavy rain.

People in South Montebello using a median park for exercise and dog walking in Los Angeles this week. The median is part of the East Los Angeles Sustainable Stormwater Capture Project.
The stones that fill a shallow trench help to capture water to recharge the aquifers.

The Army Corps of Engineers has legal control of the concrete-lined river, so federal and local authorities are on the phone around the clock. Hundreds of shore crews fanned out to physically measure flows and monitor dikes.

Building dams to ensure no water is lost during major Southern California storms like today would be financially unbearable, Lund said, likening it to building highways with so much capacity that traffic jams would never occur. In the Jan. 9 storm alone, public works engineers estimate, 18 billion gallons of water entered the ocean from the Los Angeles River.

Voters approved $2.7 billion in 2014 for dam expansions that will create 2.8 million acres of additional storage capacity, one of the biggest efforts to increase reservoirs in decades. Construction is expected to begin this year, though critics say the state has delayed the program.

Across California, water harvesting has been a mixed picture: some rivers run wild in the Pacific, while every drop is captured in others. The same applies to groundwater, but lawmakers in 2014 passed a landmark groundwater management law being implemented that will prohibit unlimited drawdowns of aquifers.

The new water harvesting effort in Los Angeles County was prompted not only by water scarcity, but by a series of environmental lawsuits that sought to stop shoreline pollution with contaminated runoff – the goal of the new system would be to not only capture the runoff, but also clean it. .

The effort, known as the Safe Clean Water Program, got off to a slow start. It was created in 2018 under Measure W, which imposed a large tax on houses and other buildings with impermeable surfaces.

Runoff from heavy storms moved down the Los Angeles River towards the ocean at Long Beach this week.

The program accumulated money with limited construction in the early years. Pestrella, the head of public works, said activity increased last year and now $400 million worth of projects have been funded, out of about $1 billion in taxes collected.

The program is the largest and most advanced technical effort to accomplish small water abstractions in the world, involving the most difficult terrain, said Mr. Pestrella.

It also has a complicated bureaucratic structure: various committees of engineers, environmentalists and other experts evaluate proposals, give technical marks and set priorities. Outside experts agree with the effort’s ambitious scope, but say the targets are optimistic.

“It wouldn’t be surprising if they got less water than they expected,” said Lund, a water specialist at UC Davis. “There are many ways for things to go wrong and when there are many ways for things to go wrong, some will.”

Mr. Pestrella acknowledged there were challenges, saying, “Water governance is always unstable.” But he added, “The program looks good to me.”

Bruce Reznik, executive director of environmental group Los Angeles Waterkeeper and chairman of the capture program’s scoring committee, said the goal of capturing 300,000 acre feet of water per year (the same amount currently captured by dams) has to work or Los Angeles will face more critical water shortages. The county’s 30- to 50-year timeline for completing the program is too slow, he added.

“It’s an ambitious goal, but we want to think big,” he said.

A concern among engineers involves maintaining hundreds of cisterns, dry wells and other features, many of which have filters and permeable bottoms that can become clogged over time.

Water infrastructure has high maintenance costs, and nearly all of Measure W’s tax revenue could be spent on maintenance at some point in the future, say some analysts.

Another variable is that some of the water that will be abstracted into cisterns may have been abstracted elsewhere in the past, said Tony Zampiello, the water master for the main San Gabriel River basin. He is the executive director of a court-appointed organization that enforces decades-old judgments that allocate water to 192 rights holders.

“It’s not new water if it had entered the system somewhere else,” he said. Another issue, he said, is how much of the water drawn from new wells actually filters into the aquifer.

The answer depends on Los Angeles County’s complex geology, which varies greatly across its watersheds. The San Gabriel River flows into the mountains in a highly permeable bed of gravel and sand. As a result, 98 percent of the flow is captured in sedimentation soils – areas designed to accelerate infiltration – and percolated into the groundwater basin for later use.

The Los Angeles River is the opposite. It starts in the San Fernando Valley and over the next 40 miles it goes down as far as the Mississippi River does over 2,500 miles. It runs through highly impermeable terrain and there is little space in its urban layout for the construction of expansion land. As a result, around 90% of its flow ends up in the ocean.

Nowhere are upcoming small-scale projects more important than in the Los Angeles River watershed, where they can impede runoff into the river and theoretically recharge underground watersheds, notes Zampiello.

Another approach the county is examining but has not yet approved is a nine-mile, 40-foot-diameter tunnel in the river that could divert water from the Glendale Narrows, where there is a significant risk of flooding. The $2.5 billion tunnel can capture up to 30,000 acres a year, said Mark Hanna, an engineer who managed a recent master plan for the Los Angeles River.

Other California counties are doing better in water retention. The Orange County Water District, south of Los Angeles, uses domestic sources for 81% of its supplies. It recycles 100% of its wastewater and captures virtually all of the water along its segment of the Santa Ana River, Southern California’s largest waterway.

Improving sewage treatment, buying settlement land and increasing storage capacity cost the district $920 million, said John Kennedy, the district’s director of engineering. “We’ve made huge investments to get to this point,” he said.