Topic: Floods

In December 2012, dam operators at Northern California’s Lake Mendocino watched as a series of intense winter storms bore down on them. The dam there is run by the U.S. Army Corps of Engineers’ San Francisco District, whose primary responsibility in the Russian River watershed is flood control. To make room in the reservoir for the expected deluge, the Army Corps released some 25,000 acre-feet of water downstream — enough to supply nearly 90,000 families for a year.

A new underground mapping technology that reveals the best spots for storing surplus water in California’s Central Valley is providing a big boost to the state’s most groundwater-dependent communities.

The maps provided by the California Department of Water Resources for the first time pinpoint paleo valleys and similar prime underground storage zones traditionally found with some guesswork by drilling exploratory wells and other more time-consuming manual methods. The new maps are drawn from data on the composition of underlying rock and soil gathered by low-flying helicopters towing giant magnets.

The unique peeks below ground are saving water agencies’ resources and allowing them to accurately devise ways to capture water from extreme storms and soak or inject the surplus underground for use during the next drought.

“Understanding where you’re putting and taking water from really helps, versus trying to make multimillion-dollar decisions based on a thumb and which way the wind is blowing,” said Aaron Fukuda, general manager of the Tulare Irrigation District, an early adopter of the airborne electromagnetic or AEM technology in California.

It was exactly the sort of deluge California groundwater agencies have been counting on to replenish their overworked aquifers.

The start of 2023 brought a parade of torrential Pacific storms to bone dry California. Snow piled up across the Sierra Nevada at a near-record pace while runoff from the foothills gushed into the Central Valley, swelling rivers over their banks and filling seasonal creeks for the first time in half a decade.    

Suddenly, water managers and farmers toiling in one of the state’s most groundwater-depleted regions had an opportunity to capture stormwater and bank it underground. Enterprising agencies diverted water from rushing rivers and creeks into manmade recharge basins or intentionally flooded orchards and farmland. Others snagged temporary permits from the state to pull from streams they ordinarily couldn’t touch.

Growing up in the shadow of the Rocky Mountains, Andrew Schwartz never missed an opportunity to play in – or study – a Colorado snowstorm. During major blizzards, he would traipse out into the icy wind and heavy drifts of snow pretending to be a scientist researching in Antarctica.  

Decades later, still armed with an obsession for extreme weather, Schwartz has landed in one of the snowiest places in the West, leading a research lab whose mission is to give California water managers instant information on the depth and quality of snow draping the slopes of the Sierra Nevada.

Land and waterway managers labored hard over the course of a century to control California’s unruly rivers by building dams and levees to slow and contain their water. Now, farmers, environmentalists and agencies are undoing some of that work as part of an accelerating campaign to restore the state’s major floodplains.

Many of California’s watersheds are notoriously flashy – swerving from below-average flows to jarring flood conditions in quick order. The state needs all the water it can get from storms, but current flood management guidelines are strict and unyielding, requiring reservoirs to dump water each winter to make space for flood flows that may not come.

However, new tools and operating methods are emerging that could lead the way to a redefined system that improves both water supply and flood protection capabilities.

To survive the next drought and meet the looming demands of the state’s groundwater sustainability law, California is going to have to put more water back in the ground. But as other Western states have found, recharging overpumped aquifers is no easy task.

Successfully recharging aquifers could bring multiple benefits for farms and wildlife and help restore the vital interconnection between groundwater and rivers or streams. As local areas around California draft their groundwater sustainability plans, though, landowners in the hardest hit regions of the state know they will have to reduce pumping to address the chronic overdraft in which millions of acre-feet more are withdrawn than are naturally recharged.

The majestic beauty of the Sierra Nevada forest is awe-inspiring, but beneath the dazzling blue sky, there is a problem: A century of fire suppression and logging practices have left trees too close together. Millions of trees have died, stricken by drought and beetle infestation. Combined with a forest floor cluttered with dry brush and debris, it’s a wildfire waiting to happen.

Fires devastate the Sierra watersheds upon which millions of Californians depend — scorching the ground, unleashing a battering ram of debris and turning hillsides into gelatinous, stream-choking mudflows. 

The whims of political fate decided in 2018 that state bond money would not be forthcoming to help repair the subsidence-damaged parts of Friant-Kern Canal, the 152-mile conduit that conveys water from the San Joaquin River to farms that fuel a multibillion-dollar agricultural economy along the east side of the fertile San Joaquin Valley.

The Colorado River Basin is more than likely headed to unprecedented shortage in 2020 that could force supply cuts to some states, but work is “furiously” underway to reduce the risk and avert a crisis, Bureau of Reclamation Commissioner Brenda Burman told an audience of California water industry people.

During a keynote address at the Water Education Foundation’s Sept. 20 Water Summit in Sacramento, Burman said there is opportunity for Colorado River Basin states to control their destiny, but acknowledged that in water, there are no guarantees that agreement can be reached.

Every day, people flock to Daniel Swain’s social media platforms to find out the latest news and insight about California’s notoriously unpredictable weather. Swain, a climate scientist at the Institute of the Environment and Sustainability at UCLA, famously coined the term “Ridiculously Resilient Ridge” in December 2013 to describe the large, formidable high-pressure mass that was parked over the West Coast during winter and diverted storms away from California, intensifying the drought.

Swain’s research focuses on atmospheric processes that cause droughts and floods, along with the changing character of extreme weather events in a warming world. A lifelong Californian and alumnus of University of California, Davis, and Stanford University, Swain is best known for the widely read Weather West blog, which provides unique perspectives on weather and climate in California and the western United States. In a recent interview with Western Water, he talked about the Ridiculously Resilient Ridge, its potential long-term impact on California weather, and what may lie ahead for the state’s water supply.