Environment |

The good news, bad news on California’s water supplies, drought after record rainfall

Let’s start with the good news.

The record-setting rain that’s pummeled Southern California over the past few days, coupled with solid water storage from last year’s wet winter, has Harvey De La Torre, head of the Municipal Water District of Orange County, offering this reassuring prediction:

“I’m very confident that we will not need drought restrictions in 2024.”

After a run of historically dry years, no part of California has been under drought conditions since September, according to the U.S. Drought Monitor. The new storm is likely to reduce water demand for weeks, with most Californians well trained to turn off sprinklers during storms. Also, state records show that both rainfall and snowpack levels — which were far below average just a couple weeks ago — are now much improved.

But in not-so-great news, water experts say conditions in this “Pineapple Express” storm haven’t been ideal for bolstering the state’s water supply.

That’s because so much rain fell so quickly that agencies controlling dams and reservoirs have to prioritize flood management over water recovery. That means releasing lots of water into the ocean.

Agency efforts to capture more stormwater in storage and groundwater recharge basins have improved in recent years, said Medhi Nemati, an environmental policy professor at UC Riverside who studies water infrastructure. But when parts of Los Angeles get 75% of their annual rainfall in just two days, Nemati said there’s only so much water agencies can do to keep up.

Also, while California mountains have certainly been getting solid snow, the storm just wasn’t cold enough to build up the massive snowpack the region needs to be insulated against dry months and years to come.

“Historically, El Niño winters weren’t that much warmer than other winters in California,” Daniel Swain, a climate scientist at UCLA, noted during a briefing on the storms. “But now they are. That’s climate change.”

Snowpack is an ideal reservoir of sorts, De La Torre said, since it stores water during winter and gradually releases it as snow melts each spring and summer. So, from a water management perspective, he said the most helpful anti-drought weather pattern would be a series of smaller and colder storms that help the snowpack pile up.

Instead, he said, climate change is fueling the opposite conditions, with longer and more intense dry periods followed by extremely wet storms that often don’t deliver much snow. That’s why, while Californians aren’t likely to face bans on outdoor watering this summer, De La Torre said we’re definitely “not out of the woods” in terms of a return to drought conditions in the near future.

That could depend on what happens in the next few weeks.

If temperatures start to rise early this year, as has happened in the past, then Nemati said the snowpack will melt too early to be of much use for water supplies, since reservoirs would still be full.

California also “still has a month left of its typically rainiest part of the year, and precipitation is still below average,” said Michael Anderson, state climatologist with the Department of Water Resources.

“Anytime precipitation and the snowpack — which is still lagging behind total state precipitation totals at only 75% of average — is below average before the end of the rainy season, there is a threat that dry conditions could set in again. However, major statewide reservoirs are still above average thanks to last year’s snowpack and are in a much better position than they were two years ago,” Anderson said.

In 2022, a megadrought that started in the West in the late 1990s had spiked, triggering unprecedented water restrictions throughout Southern California. And forecasters were largely predicting it would get worse in 2023.

Instead, the state experienced record snowpack. Local lake and reservoir levels also rose dramatically, after 33.56 inches of rain fell statewide in the water year from Oct. 1, 2022 to Sept. 30.

While experts were predicting a return to El Niño conditions that might make this another wet winter, the water year started slowly.

After measuring snowpack in the Sierra Nevada on Jan. 2, officials reported just 7.5 inches of snow, only about 30% of the average for that time of year. Based on those figures, state regulators allocated for water contractors to receive just 10% of the water they’d requested from the snowpack-fed State Water Project. Allocations will be updated later this month, though they’ll be based on January snowpack. De La Torre said it will probably be March before we see water from this storm reflected in those numbers, and not until April or May before they know where final allocations will land.

He’s optimistic that his agency, which handles wholesale water supplies for much of Orange County, will eventually receive much of what it asked for this year. The big question, he said, is whether they’ll have enough water to not only meet demands, but also store some water for the inevitable dry years to come. And, so far, De La Torre is feeling less confident about that.

Along with snowpack concerns, the Colorado River — which is critically important for Southern California’s imported water supply — remains well below average.

The river’s two key reservoirs, Lake Powell and Lake Mead, are so massive that De La Torre said they just don’t recover nearly as quickly as California’s reservoirs. The river also is fed by melting snowpack in Colorado, which this year has seen a so-so snow season. And since rivers get some of their supply from flows fed by groundwater, a recent UC Riverside study shows they don’t recover as quickly or easily from drought, with steady precipitation needed over a number of years to replenish depleted groundwater.

That’s why Nemati said we need to focus on continuing to capture more water during wet years and getting our infrastructure ready for extreme storms, with more storage and recharge projects plus upgrades to our aging delivery system.

When it comes to staying out of a drought, De La Torre said, “It’s not a sprint, it’s a marathon.”