Posts Tagged Drought

Nov 9 2015

Big Trouble Looms For California Salmon — And For Fishermen

Juvenile Chinook salmon swim in the American River in California. The state's salmon fishery, which revolves around fall-run Chinook, has been estimated to be worth $1.4 billion, with the fish finding their way into markets and restaurants.

Juvenile Chinook salmon swim in the American River in California. The state’s salmon fishery, which revolves around fall-run Chinook, has been estimated to be worth $1.4 billion, with the fish finding their way into markets and restaurants.

Courtesy of John Hannon/USBR

The West Coast’s historic drought has strained many Californians — from farmers who’ve watched their lands dry up, to rural residents forced to drink and cook with bottled water. Now, thanks to a blazing hot summer and unusually warm water, things are looking pretty bad for salmon, too – and for the fishermen whose livelihoods depend on them.

Preliminary counts of juvenile winter-run Chinook are at extreme low levels. These are salmon that are born during the summer in California’s Sacramento River and begin to swim downstream in the fall.

Unusually warm water in recent months has caused high mortality for the young salmon, which are very temperature sensitive in their early life stages. Most years, about 25 percent of the eggs laid and fertilized by spawning winter-run fish survive. This summer and fall, the survival rate may be as low as 5 percent, according to Jim Smith, project leader with the U.S. Fish and Wildlife Service’s Red Bluff office.

“That’s not good,” Smith tells The Salt.

Worse, it’s the second year in a row this has happened. Most Chinook salmon live on a three-year life cycle, which means one more year like the last two could essentially wipe out the winter run. To protect them, fishing for Chinook in the ocean may be restricted in the years ahead, when winter-run fish born in 2014 and 2015 have become big enough to bite a baited hook. The hope is that the few young fish that survived the recent warm-water die-offs will make it through adulthood and eventually return to the river to spawn.

Sacramento River winter-run Chinook are already protected by law from anglers. It’s mostly the Chinook salmon of the relatively abundant fall run — a genetically distinct strain — that wind up in the fish boxes and coolers of California’s commercial and recreational fishermen. The state’s salmon fishery has been estimated to be worth $1.4 billion, with the fish finding their way into markets and restaurants.

Chinook salmon swim in the Stanislaus River, a tributary of the San Joaquin River, in California.

Chinook salmon swim in the Stanislaus River, a tributary of the San Joaquin River, in California.

Courtesy of John Hannon/USBR


The trouble is, winter-run and fall-run Chinookwhen mingled together in the ocean — are all but impossible to tell apart by eye. In fact, many of the protected fish are almost certainly caught and killed every year.

So, when estimated numbers of winter-run fish drop too low, fishing restrictions for all ocean Chinook in certain regions along the California coast may be imposed to protect them. Peter Dygert, a biologist with the sustainable fisheries division of the National Marine Fisheries Service, says fishing regulations for 2016, including size limits and season duration, will be determined at meetings in March and April — and the recent spawning failures of winter-run Chinook will factor into the decision-making.

The water supply issues in Lake Shasta haven’t only affected the winter run. Adult fall-run Chinook are currently returning to the Sacramento River to spawn at very low levels, according to Smith. And in 2013 and 2014, meager river flows caused high juvenile mortality of this commercially important fish.

Bay Area commercial salmon fisherman Mike Hudson says the situation is unfair. “We’re all aware that fishermen haven’t caused this problem,” he says. “The way they manage water in the Central Valley has killed thousands of fish, and we might get shut down to save a few hundred.”

The U.S. Bureau of Reclamation is required by federal law to make sure enough cold water is available throughout the year at the bottom of Lake Shasta, a large reservoir at the north end of the Sacramento Valley. This cold water is critical for successful salmon spawning in the river below. For fertilized Chinook eggs, water temperatures in the high 50s and up can be lethal. Temperatures in the low- to mid-50s are more ideal.

However, in 2014 and 2015, the bureau failed to meet basic temperature requirements for salmon. Louis Moore, public affairs specialist with the Bureau of Reclamation, says a faulty temperature gauge deep in the lake is to blame. Inaccurate readings, he says, threw off calculations in 2015.

That resulted in too much water released from the reservoir early in the season and not enough cold water left later for the benefit of fish.

Many in the environmental community are not sold on this story.

“All of that is either negligence or incompetence,” says Jon Rosenfield, a conservation biologist with the The Bay Institute, an environmental group in San Francisco. “Why did they only have one temperature gauge? Saying the thermometer broke is like saying, ‘The dog ate my homework.’ ”

Rosenfield says the bureau chose to favor farmers over environmental laws, including the Endangered Species Act.

Of course, many farmers have been hit hard by the drought. Growers in parts of the San Joaquin Valley have been receiving none of their usual irrigation allotments and have had to resort to heavy use of groundwater — reserves that are becoming seriously stressed.

But in parts of the Central Valley, farmers have what are called senior water rights. This means they are last in line to get cut off when shortages occur. Rosenfield says these farmers, including rice growers near where the endangered salmon spawn, experienced only minimal cutbacks in 2015.

Even though these farmers have senior rights, favoring them over endangered fish is illegal, according to Kate Poole, a senior attorney with the Natural Resources Defense Council’s water program. She tells The Salt that protecting endangered species is supposed to be prioritized over diverting flows to farmland.

John Hannon, a Bureau of Reclamation fisheries biologist, agrees that a miscalculation was made earlier in the year, leading to unfavorable conditions in the cold water supply. However, he says the problems now affecting winter-run salmon have been caused mostly by Mother Nature.

“It just didn’t rain enough,” Hannon says.

If the drought persists through this winter, Rosenfield believes fish must be provided with generous flows while California farmers, who sold a record $54 billion in crops in 2014, must take one for the team.

“Because extinction is forever, and though economic losses for farmers are painful, they aren’t forever,” Rosenfield says.

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Oct 7 2015

Will El Niño ‘solve’ drought? Not if the rain falls in Southern California

Lake Shasta and Northern California’s other largest reservoirs, Oroville and Trinity, account for almost a quarter of the state’s surface water supplies. Combined, they can hold more than 10.5 million acre feet – or 3.4 trillion gallons – of rainwater and snowmelt. To put that in perspective, the city of Sacramento in 2014 used just 94,000 acre-feet. Greg Barnette Redding Record Searchlight file

In recent weeks, conditions have gelled for what forecasters say could be one of the strongest El Niño weather patterns in recorded history. Will it substantially ease California’s historic drought? If the storms center on Southern California, the answer is probably not.

Experts stress that El Niño is notoriously unpredictable, and when its storms do hit the state, they’re prone to soaking the southern third of California. While more than 75 percent of the demand for irrigation and drinking water is in the south state, the backbone of California’s water supply and delivery system – and most of its reservoir capacity – is in the north.

“We’re much better off if it rains in the north than in the south,” said Peter Gleick, president of the Pacific Institute, an environmental policy group based in Oakland.

In a typical year, about 75 percent of the state’s annual precipitation falls north of Sacramento, in the form of rain and mountain snow.

Four years into the drought, conditions have been far from typical. On April 1, when California snowpack generally has reached its greatest depths, the Sierra snowpack was at just 5 percent of normal. Researchers said it was the lowest it had been in more than 500 years. State officials say the 2015 “water year” that ended Sept. 30 recorded the warmest high-elevation temperatures in the 120 years people have been keeping track.

Those conditions have strained California’s massive water-delivery system, a series of reservoirs and canals operated by the state and federal governments. The infrastructure was built to take advantage of historic weather patterns, with a focus on regulating flows to prevent downstream flooding in heavy storms and capturing snowmelt to buoy the state through summer and fall.

“If you only get a series of early spring and early summer rainstorms, we’re not really designed to capture that runoff,” said Noah Garrison, a water-law expert and geologist at the UCLA Institute of the Environment and Sustainability.

The state has approximately 1,500 reservoirs, which portion out water over the year to meet demand for farm and landscape irrigation, drinking water, and fish and wildlife habitat. The vast man-made conveyance network is capable of funneling Mount Shasta snowmelt 700 miles south to San Diego.

The trick is storing the right amounts at the right times to ensure there is adequate water to meet yearlong demand in a state with enormous regions of developed land that get minimal precipitation or have just one wet season a year.

We’re much better off if it rains in the north than in the south.

Peter Gleick, Pacific Institute

In all, California has 43 million acre-feet of reservoir storage space, almost three-quarters of it north of Fresno. The largest of these reservoirs, Shasta, Oroville and Trinity in far Northern California, account for almost a quarter of the state’s surface water supplies.

Jay Lund is a civil and environmental engineering professor at UC Davis and heads the university’s Center for Watershed Sciences. During a recent interview, Lund held up a chart that showed a seemingly random scattering of points on a graph. The dots represented Sacramento River runoff during El Niño years, he said, underscoring the uncertainty of whether this year’s El Niño will substantially raise water levels in the northern reservoirs.

“It looks like a shotgun blast,” he said. “You wouldn’t want to bet on this. Maybe we will get a lot of water. Maybe we won’t.”

El Niño conditions occur when ocean temperatures warm along a stretch of the equatorial Pacific roughly twice the size of the United States. The warming leads to a shift in weather patterns that typically cause West Coast storm systems to move south.

During weak or moderate El Niño events, in which Pacific water temperatures rise by a modest amount, it’s hard to find a consistent rain pattern in Sacramento, according to a Sacramento Bee review of data back to 1950. The average precipitation in those years was 18 inches – about normal for the city. Stronger El Niño years – when ocean temperatures rise by a significant amount as they have this year – are more encouraging. During those years, rainfall in Sacramento averaged 24 inches, roughly 130 percent of normal.

If that happens, and El Niño douses central California as far north as Sacramento, it would substantially ease the burden on the state’s water supply – even if the storms don’t dump deep snow in the northern mountains, said Maury Roos, an hydrologist with the state Department of Water Resources.

Roos said there are a number of smaller reservoirs south of Sacramento that help supply the state’s Central Valley farm belt. Crop irrigation, most of it in the Valley, accounts for about 80 percent of the “developed” water in California, meaning water that people put to use.

Map of precipitation forecast and reservoir levels

“If it gets as far north as where we are, then it will help a lot more,” said Roos from his office in Sacramento. “Then you can help to refill some of the major reservoirs around the rim of the Valley.”

If the bulk of the heaviest rains stay further south, a wetter Southern California will help, but not nearly as much.

“We’re just not set up to handle the capacity, the total volume of water that we’re really dealing with,” said Garrison, the UCLA geologist. “A 1-inch rainstorm in L.A. can produce 10 billion gallons of runoff … most of which ultimately will end up flowing down the L.A. River and out to the ocean. We don’t have capacity to capture large events like that and really put them to use yet.”

Still, the situation has improved since the state’s last deep drought in the early 1990s. Several major Southern California cities and irrigation districts have made strides in recent years to capture more stormwater, reduce local use and make imported reserves last longer.

Rich Atwater, executive director of the Southern California Water Committee, said the region, on average, now gets about 12 percent of its water supply from locally captured stormwater. Southern California is investing in infrastructure improvements that should increase this capacity 5 percent, he said.

The region also gets about 10 percent of its water from recycled sewage, he said. He expects that figure to double in the next 25 years. That’s based, in part, on an ambitious plan for what would easily be the largest wastewater recycling effort in the state. The Metropolitan Water District of Southern California is discussing a project that would produce 168,000 acre-feet of potable water using treated sewage to replenish groundwater supplies.

The water district, which serves 19 million customers, recently spent close to $3 billion on a reservoir and tunnel project at Diamond Valley Lake near Hemet in Riverside County. The reservoir can capture 800,000 acre-feet – or about 260 billion gallons – of water. But for now, there’s no ready infrastructure for funneling in storm runoff from around the region. The reservoir will capture rain that falls directly in its walls, but it is only plumbed to receive water piped from Northern California.

A 1-inch rainstorm in L.A. can produce 10 billion gallons of runoff … most of which ultimately will end up flowing down the L.A. River and out to the ocean. We don’t have capacity to capture large events like that and really put them to use yet.

Noah Garrison, UCLA Institute of the Environment and Sustainability

The biggest benefit to Southern California from El Niño storms could be replenishment of groundwater supplies. In the drought, government surface deliveries have been slashed to a fraction of what they have been in average rainfall years. Central and Southern California cities and farms have been furiously pumping groundwater to make up for the loss.

Over the decades, several Southern California water districts have invested in groundwater banks and groundwater recharging projects to offset the unreliability of imports from the north and the Colorado River. These projects make use of imported water or natural flows that are channeled into swampy or porous areas where the water can seep into the ground for later pumping.

Kern County has created the state’s largest water bank, primarily to help irrigate its $7.5 billion agricultural industry. The storage network, spread across numerous irrigation districts, can hold 5.7 million acre-feet of water.

In the drought, even this massive system has been depleted. Jon Parker, general manager of the Kern Water Bank Authority, said his district alone can store up to 1.5 million acre-feet. In the drought, pumping has lowered that level to 500,000 acre-feet.

Robb Whitaker, general manager of the Water Replenishment District of Southern California, said drought-related pumping has similarly drained the groundwater stored under his district, which supplies about 40 percent of the water for 4 million people in southern Los Angeles County. He said a single wet El Niño year could put more than 150,000 acre-feet of water back into the ground.

“The basins are very, very dry. … They’re ready to capture water,” Whitaker said. “It’s like a dry sponge, and we’re hopeful we’d be able to get about twice the normal capture, if not more. In that case, we could be caught up in two or three wet seasons.”

The challenge with water banks and groundwater recharging is that too much rain too fast can overwhelm the system. Unlike a traditional reservoir, the basins that capture groundwater need time for that water to seep in.

“If the engineers and the water managers could control all the knobs like the great and powerful wizard of Oz, they would like it to come down at a moderate pace for a long time, so the system could sort of absorb it as it happens,” said Kelly Redmond, deputy director and regional climatologist for the federal government’s Western Regional Climate Center in Reno.

“If you overwhelm the system, some of it will go into groundwater recharge, but a lot of it will just go out to the ocean, and I guess your perspective on whether that’s wasted water or not might depend on if you’re a water manager or a fish.”

At the most basic level, a prolonged soaking would keep Southern California residential landscapes green longer without sprinklers. Some residents are hoping to extend that run with rain barrels, which while not widespread, have gained some traction through rebate programs.

Geri Cicero, a retired administrative assistant from Costa Mesa, is ahead of the curve on that front. She said that even before the drought, she installed rain barrels and other water-catching devices around her property. She’s anxious for an El Niño to fill them up for later landscape use.

“If you walked around my house, you’d see bucket after bucket and barrel after barrel,” she said. “It’s almost like a game for me. I really enjoy it.”

Atwater, with the Southern California Water Committee, has rain barrels, too. While they’re helpful in getting people to think about how much water they use on their landscape, he said, they can only do so much in solving the state’s water storage needs. He said he uses larger rain barrels than most people, and they’re empty within a week or two after a storm.

“A 50-gallon rain barrel doesn’t go very far,” he said.

Water storage

Shasta Lake was 35 percent full on Saturday. That’s 58 percent of the amount of water it would normally have this time of year. How the state’s largest reservoirs compare:

Reservoir Size (acre-feet) Pct. full Pct. of normal
Shasta Lake 4,552,000 35% 58%
Lake Oroville 3,537,577 30 49
Trinity Lake 2,447,650 22 32
New Melones Lake 2,400,000 11 20
San Luis Reservoir 2,041,000 19 40
Don Pedro Reservoir 2,030,000 31 47
Lake Berryessa 1,602,000 52 70
Lake Almanor 1,308,000 55 96
Lake McClure 1,024,600 8 19
Pine Flat 1,000,000 12 35
Folsom Lake 977,000 18 31

Source: California Department of Water Resources

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May 19 2015

Drought-Stricken California Organizes Unprecedented Effort to Truck Hatchery Salmon to SF Bay

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2015


What do you do when you have 30 million young salmon ready for their big journeys downstream, but drought and development have dried your riverbeds to sauna rocks? In California this year, you give the fish a ride.

State and federal wildlife agencies in California are deploying what they say is the biggest fish-lift in the state’s history through this month, rolling out convoys of tanker trucks to transport a generation of hatchery salmon downstream to the San Francisco Bay. California is locked in its driest four-year stretch on record, making the river routes that the salmon normally take to the Pacific Ocean too warm and too shallow for them to survive.

“It’s huge. This is a massive effort statewide on multiple systems,” said Stafford Lehr, chief of fisheries for the California Department of Fish and Wildlife, which since February has been rolling out four to eight 35,000-gallon tanker trucks filled with baby salmon on their freeway-drive to freedom.

“We’re going to unprecedented drought,” Lehr said. “We’re forced to extreme measures.”

Drought and heavy use of water by farms and cities have devastated key native fish in California. Last year, for example, 95 percent of the state’s winter-run of Chinook salmon died. The fish is vital for California’s fishing industries and for the food chain of wildlife.

For the first time, all five big government hatcheries in California’s Central Valley for fall-run Chinook California salmon – a species of concern under the federal Endangered Species Act – are going to truck their young, release-ready salmon down to the Bay, rather than release them into rivers to make the trip themselves.

And California’s wild native fish should pack a sandwich and something to read; they’ll be spending a lot of the summer on the road too.

“Bone dry. Bone dry,” said fish biologist Don Portz of the U.S. Bureau of Reclamation, who is six years into an effort to restore the southernmost salmon stream in the U.S., the Central Valley’s San Joaquin River.

Drought, a dam and heavy use of the river’s water for irrigation have dried 60 miles of the San Joaquin. For the young salmon, whose life cycle for millions of years has involved travel from the river back and forth to the San Francisco Bay, that now means a 1 1/2-hour ride down California Highway 99 in a pickup-mounted fish tank.

“You give them that taxi ride down, they make it to the ocean, and come back” in a few years for trapping and a taxi ride back up to spawning grounds, Portz said.

The rolling fish rescues occurring up and down the West Coast haven’t always gone smoothly. In January, Oregon authorities charged a trucker with drunken driving after he hit a pole and flipped 11,000 juvenile salmon out on the roadway, where they died.

For some of California’s native fish, the rescue from drought often is by bucket, not truck.

Near the town of Lagunitas, in Northern California’s Marin County, watershed biologist Preston Brown stood ankle-high in a coastal tributary, searching for endangered California coastal Coho salmon and other, native fish. Decades ago, so many coho salmon filled the water that the noise of their jumping kept people in nearby houses up at night. On this day, Brown and his team find none.

Starting in June, months earlier than usual because of the drought, Brown and others with local environment group Salmon Protection and Watershed Network, will search the waterway. In cooperation with wildlife agencies, they will try to rescue coho and other fish stuck in drying pools of water 4- or 5 inches deep.

Sometimes, Brown said, the bucket brigades get there too late for the stranded salmon. “If they survived the raccoons” and other predators, “they dried up and died,” Brown said.

Lehr, the fisheries chief, expects some individual steelhead trout in Southern California will get truck rides two or three times this summer, as parts of rivers and creeks disappear.

As a last resort, when some rivers have no pools of water left to shelter fish, wildlife officials will remove survivors to a hatchery to wait out the drought. Two such isolated native species from dried-up waterways have been living in government hatcheries since last year, snacking on flies that rangers catch in bug-zappers for them, Lehr said, and waiting for wetter times.

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Mar 3 2015

California salmon dodge drought bullet for another year

la-dd-california-salmon-dodges-one-more-year-o-001A fall-run salmon jumps at the Coleman National Fish Hatchery near Anderson, Calif., on Oct. 2, 1996. (Rollin Banderbob / Associated Press)

Apparently the California salmon has dodged the drought bullet for another year: The annual forecast for the fishery predicts that the population this year will be slightly bigger than last.
The initial results of the 2015 National Marine Fisheries Service survey forecasts an adult ocean population of California salmon that’s about 2.7% higher than last year.

That translates to about 650,000 fish — up from about 630,000 last year but substantially less than 2013 total of more than 800,000. Still, that’s far healthier than 2008 and 2009, when the fishery was closed completely.

The most recent figures are much better than many observers had predicted, given the devastating four-year drought the state is still enduring. With reduced water flow in the Sacramento River, some observers had feared a collapse in the population of young salmon heading out to sea.

“There’s a pretty good chance we’ll see that in the future, maybe as early as next year,” says Michael O’Farrell, a National Oceanic and Atmospheric Administration research fisheries biologist specializing in salmon.

“But we make abundance forecasts based on 2-year-old fish, and while California was certainly dry two years ago, it certainly wasn’t like it is now.”

In January, the U.S. Fish and Wildlife Service began a huge release of stocked juvenile salmon after warm temperatures and shallow waters killed an estimated 95% of the eggs laid in some tributaries. “But we make abundance forecasts based on 2-year-old fish, and while California was certainly dry two years ago, it certainly wasn’t like it is now.”

In January, the U.S. Fish and Wildlife Service began a huge release of stocked juvenile salmon after warm temperatures and shallow waters killed an estimated 95% of the eggs laid in some tributaries.

The salmon forecast is a preliminary report that will be used to set catch limits and seasons for fishermen, both commercial and recreational.

The Pacific Fisheries Management Council is scheduled to meet to make a final decision on those in April, but predictions are that the commercial season will likely begin around May 1, and that the fish will start showing up in markets shortly after.

“There have been various indicators about poor survival of fish in [the Sacramento River basin] that could indicate down the road we could have trouble,” O’Farrell said. “But we make these forecasts on a year-to-year basis, and this year our science is telling what the right thing to do is. Next year we’ll take another look and we’ll do the whole thing again.”

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Dec 8 2014

NOAA: Don’t Count On El Niño To Bring Drought Relief In California


It’s less likely an El Niño event will bring rain to parched California farms next fall or winter.

The forecast released Thursday from the Climate Prediction Center (National National Oceanic and Atmospheric Administration) said the chance of El Niño is about 70 percent during the Northern Hemisphere this summer and is close to 80 percent during the fall and early winter.

But Michelle Mead, Warning Coordination Meteorologist with the National Weather Service in Sacramento said the chance of a strong El Niño is not favored and forecasters anticipate El Niño will peak at weak-to-moderate strength during the late fall and early winter.

She said for Northern California and the San Joaquin Valley, the best estimate is for a weak to moderate event. Mead said there is little correlation between weak-to-moderate El Niño events and above-normal rainfall.

“El Niño right now is not looking like a slam dunk as far as helping us with our drought scenario,” said Mead.

Mead said if there is a strong El Niño it would means an increased chance of rain for California, but mostly for Southern California. But she said, even that is unlikely.

“The latest forecast ensemble models are actually indicating that the type of El Niño that could develop would be weak to slightly moderate and there’s no guarantee that Southern California will see increased precipitation,” said Mead.


 UC Davis researchers say “the drought is likely to stretch to a fourth straight year, through 2015, if not longer – regardless of El Niño conditions.”

“El Niño only means potential for at or above normal precipitation and we are so far behind in precipitation that even if we get normal amounts for next year it would not end the drought,” said Mead.

But she said flooding can happen very quickly, even during drought.

“You can actually have a drought scenario where one or two strong Pacific storms move in and small creeks and streams can rise quickly,” said Mead. “There won’t be a big influx of moisture and people should continue to conserve water.”

The term El Niño refers to the large-scale ocean-atmosphere climate phenomenon linked to a periodic warming in sea-surface temperatures across the central and east-central equatorial Pacific (between approximately the date line and 120oW), according to NOAA.

El Niño represents the warm phase of the El Niño/Southern Oscillation (ENSO) cycle, and is sometimes referred to as a Pacific warm episode.

NOAA said the term originally referred to an annual warming of sea-surface temperatures along the west coast of tropical South America.

El Niño events can bring flooding to some countries and drought to other countries.


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Dec 5 2014

Study: California Drought Most Severe Dry Spell in at least 1,200 Years


A car sits in dried and cracked earth of what was the bottom of the Almaden Reservoir south of San Jose on Jan. 28. (Justin Sullivan/Getty Images)

California’s current drought is pretty exceptional — like the driest in about a millennium — according to an article published today in the journal Geophysical Research Letters by scientists with the University of Minnesota and Woods Hole Oceanographic Institution in Massachusetts.

But how could they know that? There weren’t a lot of rain gauges in California in 800 A.D. — at least, not the plastic kind.

So authors Daniel Griffin and Kevin Anchukaitis looked to tree-ring samples from California blue oaks.

“California’s old blue oaks are as close to nature’s rain gauges as we get,” said Griffin, a NOAA Climate and Global Change Fellow with Woods Hole Oceanographic Institution. “They thrive in some of California’s driest environments.”

The researchers collected their own blue oak tree-ring samples from south and central California, giving them a pretty good idea of yearly precipitation in the area back to 1293. They then augmented their samples with data from the North American Drought Atlas and the National Oceanic and Atmospheric Administration Palmer Drought Severity Index.

The result: The study estimates that in the past 1,200 years, there have been 66 dry periods lasting three-to-nine years and 37 more-severe, three-year droughts. But not one of them has been as extreme as the one beginning in 2012, despite some years in the past seeing similarly low precipitation.

It’s not only lack of rain that makes a drought, though. Record-high temperatures added to California’s strife to make this dry spell the worst in more than 1,000 years, according to the study. The researchers estimate high temperatures have intensified the drought by about 36 percent.

UC Berkeley geology professor and researcher Lynn Ingram said the study’s findings appear solid.

“The tree-ring records provide the highest resolution as they have annual growth layers,” she said, adding the study provides a “cautionary lesson” about how human-caused warming “may already be impacting climate and water in California.”

Watch the California drought progress from the beginning of 2011 to the end of 2014 below. The NOAA U.S. Drought Monitor released the latest outlook today, up-to-date as of Dec. 2. More than half the state is now in “exceptional drought,” defined as “exceptional and widespread crop/pasture losses; shortages of water in reservoirs, streams, and wells creating water emergencies.”

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