What does all this rain mean for California’s drought?

By Elena Shao, The New York Times Company

Friday, March 24, 2023 | 2 a.m.

California has had an extremely wet winter, replete with severe flooding, snowed-in mountain communities and a massive snowpack accumulating in the Sierra Nevada.

So what does that mean for the state’s drought?

In January, after back-to-back atmospheric river storms, it was still largely unknown whether the downpours could reverse our drought, which began in 2020 and has stretched through the three driest years on record in the state.

At the time, many experts said that it could very likely take multiple wet months, or even multiple wet seasons, to end the drought — and there was no telling whether the wet weather early in the season would be followed by a dry spell, which is exactly what happened last year.

But this winter has continued to bring torrents of rain and snow through March, which has changed the drought outlook.

Looking at how much precipitation California received over the past three years, excluding this winter, almost the entire state experienced levels far below what’s normal — with normal defined as the average precipitation received between 1991 and 2020. But including this winter’s rain and snow, the picture shifts: The precipitation that California received between December and mid-March has offset much of the shortfall that accumulated over the past three years.

The rains have helped replenish reservoirs, many of which have quickly returned to their historical averages or surpassed them. Snow has built up snowpack levels statewide to the highest they’ve been in decades — more than three times what they were at the same time in each of the last three years.

This is undoubtedly a silver lining to the Golden State’s extreme weather of late. But experts are still hesitant to say definitively that California’s drought is over, for a number of reasons.

First, even though storms may temporarily ease the dry conditions, drought is likely to return relatively soon. California has long cycled through spells of deluge and drought, in part because of natural climate variability. But research suggests that a warmer climate has supercharged the “whiplash” between these extremes.

Second, even an extremely wet winter isn’t a magic bullet for the long-term water concerns in the state, which have been exacerbated by years of extreme aridity, rising temperatures and unsustainable water use.

California’s groundwater aquifers have huge potential for storing water; they can hold eight to 12 times as much as all of the state’s major reservoirs combined. But they have been badly depleted by decades of heavy pumping, especially in the agriculture-heavy Central Valley. Data suggests that groundwater supplies in the region decline precipitously during dry periods, recovering only modestly during wet ones.

When it comes to replenishing those aquifers, the state has had trouble capturing water from downpours and redirecting it to fields and sandy basins where it can seep underground, experts say. That means the state still has a long way to go in restoring groundwater supplies.

Heavy influxes of rain and snow during the winter can also have destructive repercussions later in the year. The state’s record-level snowpack could mean more flooding in the spring as the snow melts, especially if much of the soil is already saturated with water and can’t absorb much more of it.

And disputes over the dwindling Colorado River still loom. Seven western states, including California, depend on the river for water, but those states have struggled to reduce their water use even as the river’s flow has plummeted because of climate change, drought and population growth.

Recent rains are not nearly enough to alleviate a crisis that has been decades in the making, said Alex Hall, director of the Center for Climate Science at UCLA. “We would need multiple years of good and healthy water inputs to recover,” he said.

This article originally appeared in The New York Times.