With Snowpack in Decline, California's 'Weather Whiplash' Could Mean Alternating Drought and Flooding

California is deep into its rainy season, inching toward a make-or-break moment in building the Sierra Nevada snowpack that millions of Californians rely on for drinking water.

What’s happening here is that the state is experiencing a phenomenon called weather whiplash. Warming temperatures are deepening California’s already natural weather pattern: wet, then super-dry conditions that can be accentuated by heat waves, which can melt precious snow reservoirs early and cause flooding. After multiple atmospheric rivers in December and a virtually dry January, the state is oscillating between climate extremes in real time. 

On New Year’s Day, the statewide snowpack was 160% of normal for that date. But a month later, the snowpack fell to 92% of normal, and while that sounds relatively high, it’s been much sunnier and warmer at high elevations. Still, Sean de Guzman, snow survey manager with the California Department of Water Resources, says only about an inch of the water that’s within the snowpack has been lost. 

“Our climate is experiencing these volatile shifts from wet to dry year after year and even month after month,” he said. “That one dry month of January basically wiped out whatever head start we had.”

What’s even more daunting is there’s little to no snow or rain forecast for weeks, smack-dab in the middle of what’s supposed to be the wettest time of year. 

“We all need to be prepared for another consecutive dry year,” de Guzman said. “We are coming into February — that third (and) last month of that wet period — and the first half of it, we’re not going to be getting anything. So that’s why we’re starting to get more concerned.”

With nearly the entire state still in a moderate drought, California is staring down the prospect of a severe third year of drought, says Newsha Ajami, who studies water resiliency and is the chief development officer for research at the Earth and Environmental Sciences Area at the Lawrence Berkeley National Laboratory.

“We’re sort of hitting records very quickly, back and forth,” she said. “If you live in the Bay Area, because we depend on water that comes from the Sierra, things that happen up there can impact our water availability and water security. So, that’s why we all should care about it.”

With the great potential that this third year of drought will deepen, Ajami says water agencies and Californians need to be strategic about how we use the little water we have stored. The majority of the state’s reservoirs are well below their historical average for this time of year, including the largest reservoirs like Shasta and Oroville. 

“We don’t know what’s going to happen next, and just because we had one or two storms doesn’t mean we’re out of the drought,” she said of December atmospheric rivers that flooded parts of the Bay Area. “I just want to reemphasize the fact that our ecosystem, our groundwater levels, and our water system generally have been going through so much stress.”

Cities across Santa Clara County are already feeling the stress of two years of dry times, made worse by the region’s main reservoir being out of commission due to seismic retrofitting. Reservoirs within the Santa Clara Valley Water District, serving more than 2 million residents, are 26% full, said Gary Kremen, chair of the Santa Clara Valley Water District Board.

“More than half of the water we use is imported hundreds of miles away, and the source of that is the snowpack,” Kremen said. “When the snowpack is good, generally that’s very good for us. And when it’s down below average, that’s not as good.”

Kremen says despite the worsening state of drought, water use in December increased by 4% from 2019 levels. He says residents need to live as if no more rain is in the future.

“I know folks kind of had enough hearing from the government saying, ‘Do this or do that,’ but just like the virus, it’s important,” he said. “We’re hoping conservation will work, so we don’t have to need restrictions. But we can’t count on that. That’s why it’s super important to save every drop.”

‘More rainfall and less snow’

Although the state is locked in a dry pattern, state water officials are also worried about the opposite. Scientists forecast that as the climate continues to warm, much of California’s snow will fall as rain, causing massive flooding.

The Department of Water Resources will be updating its Central Valley Flood Protection Plan sometime in March with new projections of what flooding could be like in a warmer climate. Mike Mierzwa, the state’s floodplain manager, says it will showcase how warming temperatures will lead to an exponential rise in flooding.

Snow typically melts slowly into rivers that run down from deep in the mountains, but that’s gradually changing as the climate warms. 

“With climate change, you’re going to have more and more rainfall and less snow. So, that means more water all at once,” said Mierzwa.

One-hundred-year flood events along the San Joaquin River could grow in severity by as much as fivefold over the next half-century, causing billions of dollars in damage to large population centers like Stockton and small towns like Firebaugh. 

“Not taking action, hundreds of lives per year could be lost,” Mierzwa said. “When a big event happens, it could be an event on the order of what happened in New Orleans.”

Warming temperatures will also increase the size of minor floods that happen every five to 10 years. And even those floods can be deadly.

Mierzwa says DWR will propose solutions for a far wetter future in places like Stockton. These range from raising levees, making room in reservoirs, and flooding farms or parks when flows are high. 

John Cain, the conservation director for the nonprofit River Partners, would like to see large land areas opened up for rivers to spill into during huge rain events. Bypasses have helped protect places like Sacramento from flooding, but further south, he says, Stockton needs ways for the river to escape without harming people or property during big flood events. 

“The Sacramento Valley has seen huge investments in the levee and flood bypass system over the 19th and 20th centuries, and by contrast, the San Joaquin Valley is that poor stepchild [that] hasn’t gotten the attention,” he said. 

Stockton is one of the places most vulnerable to a significant flood in all of California. On the south side of the city, next to Interstate 5, the Van Buskirk Levee holds back an arm of the San Joaquin River from hundreds of homes.

As a longtime environmental advocate and Stockton resident, Barbara Barrigan-Parrilla is worried this levee could easily overtop or fail, flooding a neighborhood of primarily Black and Brown working-class residents’ homes. 

“If California’s Fourth Climate Change Assessment is correct, we’re going to have overtopping of levees on both sides here,” she said. “To leave this side of the city with such an inadequate levee is just morally wrong.”

Protecting Stockton’s 300,000 people will take remedies such as flooding farms in the worst storms, and will need to include strengthening levees, which is already happening in some parts of the city. But so far there is no real solution set in stone for the Van Buskirk Levee, says Chris Elias, executive director of the San Joaquin Area Flood Control Agency. 

“Priority 1 is life safety, then property — because they don’t want to cause dislocation to people’s lives — and then the economy,” he said. 

The new projections from state water officials likely will complicate reinforcing the levee, and he says progress is trickling, not flowing. 

“We are working very closely with the city to look at what the options are and how we can collaborate for a win-win-win solution,” he added. 

But for a solution to be a win for all Stocktonians, Elias says it must protect lower-income neighborhoods just beyond this existing mound of dirt.