A trio of storms that rolled through the Central Coast last weekend brought rain, hail and high winds that led to flooding, downed trees, power outages and numerous vehicle crashes, but the precipitation did little to lift Cachuma Lake from its drought-distressed condition.
In fact, the reservoir appears to lie just inside the last 2.13 percent of California classified in “exceptional drought” by the U.S. Drought Monitor website.
On Monday, the weekly map showed the southern portion of Santa Barbara County, most of Ventura County, the northwestern tip of Los Angeles County and a slice of southern Kern County within the D4 classification, the worst on a five-level scale of drought.
Cachuma Lake could be considered the poster child for exceptional drought. While 42 percent of the state is no longer classified as suffering from drought, that part is in Northern California, where most of the storms have passed through and left behind large amounts of precipitation.
The other 58 percent under various drought classifications makes up the lower half of the state, where not enough rain has fallen to saturate the soil and create runoff.
“Given the protracted nature of conditions from much of the San Joaquin Valley southward to Mexico, no improvement was introduced there, including the persistence of D4 conditions in part of southwestern California,” Richard Tinker and Anthony Artusa of the National Oceanic and Atmospheric Administration’s Climate Prediction Center wrote in a summary of the latest storms.
As of Monday night, Cachuma Lake was holding just 21,668 acre-feet or 11.2 percent of its capacity — up from the 9 percent it was holding just over a week ago but still dismally low.
An acre-foot is about 326,000 gallons, or the amount of water generally needed to supply the annual needs of four to 10 people in an urban environment, and at capacity, Cachuma Lake holds 193,305 acre-feet.
“Last year at this time it was at 28,600 acre-feet, so therre’s not a lot of change on the Lake Cachuma front,” Solvang City Manager Brad Vidro told the City Council at its Jan. 23 meeting.
“The storms did add about 4,000 acre-feet to Cachuma and the inflow continues,” he said. “They do expect Gibraltar (Reservoir) to spill later … which will increase the flow into Cachuma.
“So while therre’s lots of water and rain, Cachuma is still not much of a lake at this point,” Vidro added.
A lot more rain and runoff will be needed to significantly raise the lake’s level.
“Of course, we’re pleased to see some runoff into the Santa Ynez River,” said Fray Crease, the county’s water agency manager. “Cachuma has risen about five feet in the last week or so. But it’s way too soon to be out of the woods.
“If you look at it from a local level, the lake is still historically low,” she said. “It’s still 100 feet down from the spillway.”
Crease said it will require a steady stream of rainstorms over an extended period of time to have a real impact.
“Earlier this winter, we had a series of small storms — quarter-inchers to half-inchers — that put a lot of moisture into the soil,” she explained. “So this last storm actually produced some runoff. But it looks like it will be dry for the next week, at least.”
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Crease said the watershed needs to become saturated, then hit with a steady procession of rain storms. That will produce runoff into the creeks and river that feed Cachuma.
Had the area received the five to 10 inches of rain some forecasters predicted, the lake likely would have seen the highest rate of runoff since 2011.
Recent rains brought Gibraltar Reservoir east of Cachuma up to 96.7 percent of its capacity from the 15 or so percent it was holding just last Friday.
But Crease noted it’s a much smaller reservoir, its watershed is very large and the Rey fire, which charred 33,606 acres of forest in August and September, had more of an impact on its watershed than on Cachuma’s.
With all the vegetation burned away, there was nothing to capture the rainwater and make it soak into the ground, so more of it flowed down the hillsides and into the reservoir, helping to push it nearly to its 5,246-acre-foot capacity.
On the other hand, Twitchell Reservoir, located east of Santa Maria in the much larger D3 or “extreme drought” area that stretches north, south and east, was holding just 5.5 percent of its 194,971-acre-foot capacity Monday.
Reservoirs in San Luis Obispo County fared much better than Cachuma as a result of recent storms.
John Lindsey, meteorologist for Pacific Gas and Electric Co. at Diablo Canyon Power Plant, said Nacimiento Lake, which sits entirely in San Luis Obispo County, and Lake San Antonio, which is just north of the San Luis Obispo County line, saw significant increases in their levels.
Since Jan. 3, Nacimiento's storage went from 25 to 75 percent of capacity as of Monday, the highest level since 2011. Lake San Antonio went from 6 to 22 percent of capacity as of Monday.
“Large watersheds feed both of these lakes, but Nacimiento Lake, as a rule, will fill up about three times faster than Lake San Antonio due to the larger size and proximity of its watershed to the Pacific,” Lindsey said.
Lopez Lake east of Arroyo Grande has risen 15 feet and is now at 33 percent of capacity, according to data from SLOCountyWater.org.
The Salinas Reservoir in Santa Margarita went from 31 to 58 percent, and Whale Rock Reservoir near Cayucos is now at 52 percent, according to SLOCountyWater.org.
The U.S. Drought Monitor map is produced jointly by the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture and the National Drought Mitigation Center at the University of Nebraska-Lincoln.
Meteorologists and other scientists there use a variety of standard measures, including a drought severity index, soil moisture model, weekly stream flows, a standardized precipitation index and objective drought indicator blends to develop the drought classifications.
The website notes that "drought" means a moisture deficit severe enough to create social, environmental or economic impacts.
As a result, the classifications usually describe the main physical effects of short-term droughts of less than six months and long-term droughts of more than six months.