EXPLAINER: How much will the rain help California’s drought?

EXPLAINER: How much will the rain help California’s drought?

California has experienced a devastating, multi-year drought That’s depleted reservoirs, forced officials to ask residents to conserve water, and limited supplies of vital farmland.

Suddenly, the state was hit by a severe series of storms, more are expected in the coming days. The rains are drenching a state in dire need of water, even as it takes a devastating human toll. Experts say it will help with drought conditions, but it’s not yet clear exactly how much. And rain and snow won’t be enough to solve some of California’s long-term water problems that climate change is getting worse.

“We’re transitioning into a climate that’s warming and becoming drier,” said Jeannie Jones, manager of interstate resources at the California Department of Water Resources.

Here’s how the storms will impact California’s long drought battle:


California has experienced six atmospheric flows in the past few weeks and is preparing for up to three more, with wild weather set to continue for at least another week, Gov. Gavin Newsom said Tuesday from Santa Cruz County, where raging seawater damaged an iconic wooden walkway .

The storms poured a tremendous amount of water across the state, particularly in central California, including the San Francisco Bay Area and the Sacramento Valley. Rainfall is 138% of the average for this time of year, officials said. The storms have also dumped snow on the Sierra Nevada, which runs along California’s eastern border.

Some depleted reservoirs have begun to fill, particularly those near the hard-hit Sacramento region and along parts of the Sierra Nevada. The reservoirs are essential for irrigating the Central Valley, a productive farmland that grows large amounts of fruits, nuts, and grains. The reservoirs also provide water to millions of people in coastal cities.

For example, a small reservoir in Sonoma County that was at about half its historical average as of Christmas had risen to 80% of that average as of Monday.

“What we have so far puts us in good shape, probably for next year at least,” said Alan Haynes, the hydrologist in charge of the California Nevada River Forecast Center.

So far, this is also one of the best years for snow cover accumulation in decades, according to state officials. Snowpack is a proprietary type of reservoir that retains moisture that ideally melts slowly in reservoirs, providing residents with water during the drier months of summer and fall. In addition to rain, the storms dumped snow, which helped bring total snowpack to more than double the average for this time of year.


It’s still early winter and it’s unclear what the next few months will bring. Last year, the nationwide snowpack around this time also looked promising. But a few warm, dry months followed, and when snowpack was expected to peak in early April, it was just 38% of historical averages.

“We’re not out of the drought yet,” said Laura Feinstein, who leads work on climate resilience and the environment at SPUR, a public policy nonprofit.

Also, the storms haven’t dropped as much water on Northern California. A reservoir on Lake Shasta, which was at 55% of its historical average at Christmas, was up to 67% by Monday — an improvement but still well below the historical average due to years of water shortages, Haynes said.

The atmospheric fluxes are not conspicuous everywhere. They move “like a garden hose when you spray it across the yard,” said David Gochis, an expert on the effect of water on weather at the National Center for Atmospheric Research in Boulder, Colorado.

“These biggest reservoirs are just so massive that it’s probably going to take a while to fill up,” he said. Some of the largest and most important reservoirs could require five or six such soaks, he said.

David Novak, director of the National Weather Service’s Weather Forecasting Center, says the atmospheric fluxes that are yet to come are likely to be weaker. The problem is that the already wet floor can’t hold much more water, causing drainage issues. In about 10 days, weather patterns could change and eventually “turn off the faucet,” he said.

And the Colorado River, a major source of water for Southern California, has also been hit by a drought that has depleted major reservoirs on that river. The recent storms will not solve this problem.


Many California farmers pump water from underground, with the massive amounts being drawn from aquifers depleting groundwater. Some wells dry up. It’s an entrenched problem that won’t be solved by a short-term series of storms, experts said.

And California faces a long-term problem. Although a few wet years have been added, drought has persisted in California for approximately two decades. Climate change is making for drier and hotter conditions. Water evaporates faster. California officials predict there will be less water in the future.

“So in that big picture, this series of storms is really just a drop in the ocean,” Jones said.


The Associated Press receives support from the Walton Family Foundation for reporting on water and environmental policies. The AP is solely responsible for all content. All of AP’s environmental reporting is available at https://apnews.com/hub/climate-and-environment


Associated Press writers Seth Borenstein in Denver and Kathleen Ronayne in Sacramento contributed.

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