Los Angeles Times
Our wild, wet winter doesn't change this reality — California will be short of water forever
Jay Famiglietti and Michelle Miro
Over the last 18 months, California has experienced one of the driest, wettest and wildest rides in its recorded water history.
As the 2015-16 water year opened in October 2015, drought had driven the state’s reservoir and groundwater levels to all-time lows. Entire towns were left without water. Reports of lakes turned to puddles, of wells running dry by the thousands, and of the cracked ground above depleted aquifers sinking several feet a year.
Then came the deluge. Since last fall, a steady stream of “atmospheric river” storm systems has been battering the coast, the Sierra Nevada and almost everywhere in between, restoring reservoirs and the snowpack to their highest points in years.
All winter, Californians have been asking one question: Is the drought finally over? The federal monitor shows just a few lingering tan and yellow patches in Southern California, but for scientists, the beginning and end of drought conditions are exceptionally difficult to pinpoint. Still, after only a few more serious encounters with the “Pineapple Express,” Gov. Jerry Brown may well declare the state’s 3-year drought emergency over.
The great thirst of our highly productive agricultural sector has never been and will never be satisfied by the annual winter storms.
Which leads us to the second most frequently asked question of this unusually wet winter: What’s our water future? The answer has been clear for a while: It’s going to be a lot like our water past, but more so — California is, was and will be chronically water short.
The drought has underlined three important realities that aren’t going to change.
First, the way municipalities use water can be sustainable, even as their population grows, as long as they embrace conservation, water recycling and reuse, and a diverse portfolio of management options. However, agricultural water use at today’s scale in California is not sustainable. Agriculture is literally sucking the state dry.
Food production requires nearly unfathomable volumes of water, and has resulted in the long-term decline of the total available fresh water in California. The great thirst of our highly productive agricultural sector has never been and will never be satisfied by the annual winter storms that feed the state’s rivers and reservoirs.
The shortfall is met by pumping groundwater at rates that greatly exceed those of replenishment. As a result, groundwater levels in much of the state, including the once-vast reserves beneath the Central Valley, have been declining for nearly a century.
It is essential to understand that wet winters like the current one will not reverse this long-term decline. Historically, even the wettest multiyear periods result in only a modest uptick in the otherwise steady loss of Central Valley groundwater.
Consequently, agriculture in California has to adapt to this dwindling supply. Farmers and ranchers will face more of the kinds of difficult decisions the drought has already forced, such as fallowing fields as groundwater levels drop, or worse, taking land out of production.
Next, we must recognize that the classic definition of water as a sustainable resource — that is, using only the surface and groundwater available on an annual, renewable basis — is no longer tenable for the entire state. Instead, water sustainability in California must now refer to efforts to slow the rate of disappearance of the state’s groundwater reserves.
The landmark Sustainable Groundwater Management Act, passed in 2014 in Sacramento, acknowledges and confronts the declining availability of fresh water in California. Its requirements, however, will never result in the recovery of statewide groundwater levels, even if important efforts to enhance groundwater recharge and construct additional storage are pursued.
Finally, it is simply impossible to effectively plan for California’s water future without knowing a lot more about how much water the state has, how much it needs and how these amounts are changing with time.
The amount of groundwater remaining in the state’s aquifers hasn’t been adequately measured; it must be quantified by exploration. This includes characterizing how its quality degrades with depth, and estimating the costs and environmental consequences of pumping and treating this deeper, lower quality groundwater.
Estimating California’s diverse water needs — for food and energy production, for domestic and municipal supply, for the environment and for economic growth — requires precise measurement, as well as a partnership between water management entities and the research community so that advanced, science-based tools can help establish trade-offs among allocation options.
Climate change and population growth are the primary drivers of changing water supply and demand, but other factors will also be important in managing the gap between the two. For example, personal water-use habits, greater agricultural efficiency, new technologies like potable reuse and desalination, and changes in water pricing, rights and policy will all affect the state’s water availability and needs.
At the beginning of this month, and with a few weeks of winter still to come, the snowpack in the southern Sierra measured 201% of average. That’s a lot of snow and great news for a parched state. But the long-term disappearance of groundwater will persist, and water scarcity is California’s once and future reality.
Embracing this distinction, understanding its causes, working to mitigate them and monitoring our water down to the last drop are the essentials of the new, post-drought era of California water.
Jay Famiglietti is a hydrologist and former professor of Earth system science and of Civil and Environmental Engineering at UC Irvine. Michelle Miro is a hydrologist and doctoral candidate in civil and environmental engineering at UCLA.
Los Angeles Times
Damaged Oroville Dam spillway may need to be used by next week, state officials say
A damaged flood control spillway at the Oroville Dam may have to be used as early as next week as storm runoff and snowmelt continue to fill the massive reservoir on the Feather River, state water officials said.
The spillway has been dry since Feb. 27, when engineers with the Department of Water Resources rapidly reduced the flow of water down the concrete chute from 50,000 cubic feet per second to zero so they could repair the spillway and restart a nearby hydroelectric plant.
But since that shutdown, the water level in the reservoir has climbed 21 feet, even though the power station began operating last week. The reservoir’s water level was at 859 feet Thursday afternoon, 41 feet below capacity and only 6 feet shy of the threshold at which engineers have said they’ll want to use the spillway again.
But using the spillway in its current state carries risks, officials said.
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Engineers discovered last month that if they allow water to flow down the spillway too slowly, it erodes the earth beneath the structure, further compromising the spillway and possibly, eventually, the dam.
Crews have spent the last week filling the area below the damaged section with rocks and concrete slurry to prevent further erosion, but officials couldn’t say Thursday if the spillway could handle reduced flows.
Instead, they’ll only use the spillway when water can be released at upward of 40,000 cubic feet per second, Department of Water Resources spokeswoman Lauren Bisnett said. The spillway’s limited capabilities mean that in the short term, engineers will continue to operate the reservoir like a yo-yo, allowing it to fill up before opening the spillway gates and releasing massive amounts of water, then closing them and repeating the process when it fills up again, officials said.
On Thursday, Butte County Sheriff Kory Honea revealed a new warning and evacuation plan for the county’s residents, many of whom were forced to flee to high ground with only an hour’s notice last month when state officials feared a portion of the reservoir’s emergency spillway was nearing failure.
“Our goal is to give people 12 to 24 hours notice” and reduce choke points for fleeing residents, Honea said.
San Francisco Chronicle
After near-record Northern California storms, signs of El Niño rise
If you don’t think California has seen enough rain this year, just wait. There may be more to come.
Federal forecasters said Thursday that the chances of an El Niño developing by fall are on the rise — now between 50 and 55 percent —an outlook that could skew the odds in favor of yet another wet winter.
“There are a lot of players on the (weather) field,” said Emily Becker, a research scientist with the Climate Prediction Center, the federal agency that released the latest report on the El Niño climate pattern. But “El Niño is associated with an increased chance — not a 100 percent chance, but an increased chance — of higher-than-average rainfall in California.”
The state is already seeing some of its wettest weather in recorded history.
According to Golden Gate Weather Services, this year’s rainy season, going back to July, has seen just 0.27 inches less than the record-setting 28.30 inches of rain that had fallen — on average across the state — at this point in the soggy 1968-69 rain year.
Meanwhile, precipitation in the northern Sierra, which is crucial to the state’s fickle water supply, is tracking ahead of any previous year. As of Thursday, an average 77.8 inches of precipitation had fallen between Mount Shasta and Lake Tahoe since Oct. 1 — about 212 percent of average for the period, according to the state Department of Water Resources.
The nearly constant barrage of Pacific storms, often called atmospheric rivers because of the sheer volume of water they carry, has lifted almost all of California out of a historic five-year drought.
The U.S. Drought Monitor classified just 8 percent of the state in drought Thursday, compared with 97 percent a year ago.
While the reasons behind the relentless pounding remain a subject of study, scientists recognize that the deluge came on the heels of a weak La Niña — not typically a climate signal that denotes wet weather for the Golden State.
La Niña, which is the opposite of its sibling phenomenon and is marked by cool surface temperatures in the tropical Pacific, has been associated with dry weather in California when the pattern is strong.
“By any formal metric, this winter was unanticipated,” said Daniel Swain, a climate scientist at UCLA. “The deeper question of why it’s happening is challenging. I don’t think we have a good answer.”
Swain and other forecasters were taken by surprise last year, too, when a strong El Niño produced only a moderately wet winter. With Pacific equatorial temperatures at record highs — the telltale sign of a robust El Niño — many expected loads of rain and snow in the 2015-16 season.
While the rain year left most of Southern California dry, it was still wetter statewide than prior ones and introduced what would soon become a rapid recovery from drought.
Forecasters say it’s too early to know just how strong a potential El Niño could be in the coming year. Its intensity remains key to predicting precipitation.
If the El Niño turns out to be strong, Swain said, there’s an elevated chance of another wet winter for California.
“Even thought it didn’t work out for us last time,” he said, “it doesn’t mean we shouldn’t expect it to next time.”