When Is a Drought Over? A Wet California Wants to Know

http://www.nytimes.com/2017/03/10/us/california-drought-snowpack.html

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LOS ANGELES — The Hollywood Reservoir is nestled in a basin surrounded, usually, by dusty brown hillsides, broken up by the occasional dry wisp of shrubbery. Not these days. After yet another burst of rain the other day, the hills were transformed into lush fields of knee-high grass, spotted with purple flowers. And the reservoir? As high as it has been in years.

In Northern California, snow could be seen on top of Mount Diablo outside San Francisco last weekend. Across the state, dams are under siege and reservoirs are overflowing. The snowpack in the Sierra Nevada — a source of water once winter ends and the dry months settle in — was nearly twice its normal level last week. (And that was before even more snow arrived.)

Yet for all that, California is, at least officially, still in a drought state of emergency. That has been the case since Jan. 17, 2014, when Gov. Jerry Brown issued the order after one of the driest years in California history.

Why hasn’t the drought been declared over? Here are some answers for Californians — and everyone else who has watched this story unfold — about what is going on.

So is California ever going to end its drought emergency?

The answer is yes, or at least probably yes. “Very soon, but not right away,” Mr. Brown told reporters last week. “We are going to wait until the end of the rainy season.” In other words, about six weeks.

Why the wait? The Sierra Nevada snowpack is now at 181 percent of normal. There was hail in San Francisco the other day. People in Los Angeles are actually learning to drive in the rain.

To appreciate just how striking that snowpack statistic is, consider this: When Mr. Brown attended the final snowpack measurement of the season in April 2015, there was not a patch of snow in sight. That was when he ordered a mandatory 25 percent reduction in urban water use, and he met little resistance.

But Mr. Brown has seen enough droughts over his 78 years in California to know the risks. The snowpack, a central cog in California’s nature-defying system of providing water to 40 million people, is ephemeral: A warm April or May could melt it away. That happened, to some extent, last year. The reason is climate change.

And while most of California — 74 percent as of last week — is officially out of drought, parts of the state, such as Santa Barbara, remain alarmingly dry. “Some Central Valley communities are still depending on water tanks,” said Nancy Vogel, the deputy secretary for communications at the California Natural Resources Agency.

Do Californians still have to cut back their water use an average of 25 percent from pre-drought levels?

That was the original directive by the governor, and Californians responded by meeting — and in some cases beating — the order. But because of that, and because conditions have improved, the State Water Resources Control Board eased up on the statewide mandate last year. The updated rules vary by region. In some places, there are no restrictions; in others, they remain relatively strict.

“What’s really remaining is the monthly reporting and the bans on wasteful water use — the obvious stuff like watering so much that it runs into the street, hosing down your driveway,” said Felicia Marcus, the head of the Water Resources Control Board. “The reporting and the wasteful practices are things that the governor has asked us to make permanent. And we are working on making them permanent.”

Are Californians conserving less water than they did when the order was first issued?

They are, but it’s still better than you might think.

The rule that prohibits restaurants from serving water to customers without being asked seems to have gone, um, down the drain, at least in many places. But not all the gains in water conservation were a result of behavioral changes, like taking shorter showers or watering gardens just twice a week.

At the height of the emergency, many homeowners replaced lawns with drought-resistant gardens, often with the help of subsidies from water agencies in cities like Los Angeles. New homes are being built with low-flush toilets and restrictive shower heads, and lawns have given way to desert landscaping. Those kinds of changes produce lasting effects: Urban water use was down 20.5 percent in January compared with the same month in 2013, state officials reported Tuesday.

Is the state being too cautious? Think the boy who cried wolf: Isn’t there a risk that people who responded so valiantly two years ago will take things less seriously the next time around?

That is always a risk state officials have to consider in determining when to declare the beginning or end of a drought. Beyond that, weather is, of course, ultimately unpredictable. California was girding in 2015 for a soaking El Niño weather pattern that never came. And before this winter began, some meteorologists were predicting a La Niña pattern, which would have meant drier conditions than usual. That certainly didn’t happen.

“This year may be only a wet outlier in an otherwise dry extended period,” Ms. Vogel said. “Unfortunately, the scientific ability to determine if next year will be wet or dry isn’t yet capable of delivering reliable predictions.”

In the end, has the drought been as bad as everyone worried it might be?

Probably not, though it is up there with one of the worst droughts in California’s history. The last severe drought here lasted from 1987 to 1992. At the time that Mr. Brown acted, the state was in the midst of what would turn out to be the driest three-year period in its recorded history.

California has always suffered cyclical droughts, but there was considerable concern that global warming was making conditions worse. And many people in Southern California, where growth is booming, have to rely on water that is piped in from other places, mostly from Northern California.

“I had to look at the worst-case scenario,” Ms. Marcus said. “I was worried. We had to act as if we were having our own millennial drought that would last 10 years. It was definitely DEFCON 1.”