Now that 2016 has gotten off to a wet start, with a series of El Niño storms drenching California in recent days, the question is turning up with increasing frequency at dinner parties and coffee shops:
“How will we know when the drought is over?”
The answer, water experts say, is more complicated than you’d think.
Simply put: The drought could end this year, according to state water officials. But for that to happen, as California enters the fifth year of the worst drought in the state’s history, rains will have to continue arriving in pounding, relentless waves through April to fill depleted reservoirs and dry rivers and push the Sierra snowpack to at least 150 percent of normal
“One week of rain doesn’t make up for four years of historic drought. We are in a very deep hole,” said Mike Anderson, California’s state climatologist.
Other disasters are easier to understand. Everyone knows when a forest fire is contained, an earthquake stops shaking or a tornado has passed.
But with California droughts, there isn’t widespread agreement among scientists and water managers about what signifies the finish line. California is a huge state, with many different climates, water sources and water users. Decent rain over a few months may be enough to grow green grass so that a Sacramento Valley cattle rancher’s business returns to normal in one season. But it might not fill reservoirs enough so a Bay Area city can lift water conservation rules.
“As they say, all politics is local. And all droughts are local,” said Jeanine Jones, a top drought manager at the state Department of Water Resources. “The impacts are in the eye of the beholder.”
Many experts say that if the state’s big reservoirs fill, the drought will be over because it will be nearly impossible to convince Californians there is a drought emergency when they see water rushing over spillways and headed out to sea.
Others say California needs to make up the sizable rainfall deficit over the past four years, which almost certainly won’t happen this winter. Other experts say that California has to replace billions of gallons of overpumped groundwater to have a true recovery — which will take decades.
“How will we know when the drought is over?” said Leon Szeptycki, a water use attorney and executive director of Stanford’s Water in the West program. “That’s a really good question. There are lots of different answers.”
The final decision will rest with Gov. Jerry Brown.
He declared a statewide drought emergency Jan. 17, 2014, and he is the one who eventually will rescind it.
Jones said various state agencies have been meeting nearly every week as part of a drought task force. They will make a recommendation to the governor about whether to lift the drought declaration at the end of the winter rainy season — probably not before April — after it’s clear how much rain and snow fell, she said.
How far do we still have to go?
Anderson researched years when other major droughts were widely considered to have ended: 1938, 1978 and 1993. In each case, the Sierra snowpack — the source of one-third of California’s water supply — was roughly 150 percent of the historic average. And precipitation levels at eight key weather stations in Northern California, located in watersheds that feed Shasta, Oroville, Folsom and other massive reservoirs, also was between 130 percent and 150 percent of normal.
His conclusion: If California receives 150 percent snowpack by this April and 150 percent of normal precipitation in the north, that should be enough to fill the biggest reservoirs and probably end the drought.
On Friday, the Sierra Nevada snowpack was at 107 percent of the historic average, and the eight-station index was at 94 percent.
“I’m encouraged. It’s glorious. I went up to the Sierra last week, and I wanted to kiss each snowflake,” said Felicia Marcus, director of the State Water Resources Control Board. “It was spectacular. It was tinged with the fact that I know it could still get warmer and melt, but I’m trying to look at it as a glass half full.”
On Feb. 2, the board will vote on whether to relax the mandatory water conservation rules that have been in place since last June. Those require a statewide reduction of 25 percent in urban water use, and cities and water companies that violate the rules face fines. They have forced hundreds of water agencies to impose water restrictions.
The board is expected to ease the rules somewhat in areas with hotter climates or fast population growth, while keeping most of them in place. However, it will come back in April for another look, Marcus said.
“If we are flush, then we’ll drop them then,” she said. “If we are in some middle ground, we might adjust them and ease up a bit.”
One of the biggest problems statewide is that nearly every major reservoir is at dangerously low levels. Since Dec. 8, rain has boosted the level of Shasta Lake, the state’s largest reservoir, by 12 feet, adding 168,000 acre feet of water — enough for 840,000 people’s needs for a year.
That’s impressive, until you realize that all that water only increased Shasta’s storage by 4 percentage points, to 33 percent full.
Similarly, all the recent rain raised the 10 reservoirs in Santa Clara County to 31 percent full, up from 29 percent on New Year’s Day.
“There’s still an awful lot of room in those reservoirs,” Anderson said.
And then there is the rainfall deficit.
Since the drought began in 2011, most major cities in California are missing at least a year of supply.
San Francisco, for example, receives 23.65 inches of rain in an average year. So over five years, it should have received 118.25 inches. But so far, since the drought began, it has received just 72.37 inches. That means that to get “back to normal,” the city would need 45.88 inches this rainy season.
The record wettest year in San Francisco was 49.27 inches, during the winter of 1861-62.
Similar shortfalls of 25 to nearly 40 inches exist in San Jose, Oakland, Fresno and Los Angeles.
In strong El Niño years like this one, history shows, the chance of a wet winter in California is greater. But it’s not guaranteed.
“The big question is: Are we going to stay in a wet pattern?” said Jan Null, a meteorologist with Golden Gate Weather Services in Saratoga. “We don’t have much skill after a week or two to know for sure.
“The fact that we have a very strong El Niño in place loads up the dice a little bit in favor of it being wetter,” he said. “But even loaded dice don’t always come up the way you want.”
NASA scientists using satellite data estimate that California is 12 trillion gallons of water short because of the drought — in rivers, creeks, snowpack and, most importantly, in underground aquifers that have been pumped at record levels by Central Valley farmers. Groundwater experts say that will take decades to recover. And it might not ever happen.
“California suffers from what I call ‘chronic water scarcity.’ We simply don’t have enough water to do all the things that we want to do,” said Jay Famiglietti, a senior water scientist with NASA’s Jet Propulsion Lab and a UC Irvine professor of Earth systems science.
Famiglietti said farms need more drip irrigation, changes in water pricing and perhaps importing more water from out of state to stay sustainable in the future. Making up the lost 12 trillion gallons of water could take four years of normal or above-normal rainfall, he added.
When the drought does finally end, some leaders will push to make certain rules permanent, such as not allowing anyone to water grass within 48 hours of rainfall or requiring hotels to ask customers if they want to waive washing sheets and towels.
“It’s rained a little, so we’re all celebrating right now,” said Dick Santos, a director with the Santa Clara Valley Water District. “It’s like the economy. Things are going good right now, but they won’t always be. Rainy days are going to come, but don’t be fooled. Our population is growing, and California is a dry state. Droughts will come back. We should be better prepared next time than we were this time.”
Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN
