Rain season 2016-17 has a good shot at once again providing enough water to slake Napa County’s thirst, though busting California’s five-year drought is a taller order.
A multi-year drought could require a multi-year fix. State Department of Water Resources spokesman Doug Carlson said more than one normal rain year is probably needed.
“An extremely wet year might do the trick, but that’s seemingly unlikely based on the weather patterns we’ve seen over the last several years,” Carlson said.
The drought has badly hurt parts of the state. Well levels are plummeting in the Central Valley, hurting towns, rural homes and farms. Pine trees are dying by the millions in the southern Sierra Nevadas.
Napa County hasn’t escaped the drought. Still, Napa State Hospital has received 80 percent of normal rain over the past five years and last year’s total of more than 24 inches was near normal.
Following the 2015-16 rain season, Napa Valley last summer was once again green with grape vines. The National Weather Service measures rainfall from July 1 through June 30.
“The water year for us in total was actually really good,” said Garrett Buckland of Premiere Viticultural Services. “In Northern California, we received roughly around our average amount of rainfall.”
Late spring, rains recharged the soils with water and allowed some vineyard owners to cut water use by 20 percent to 30 percent, he said.
The city of Napa enters rain year 2016-17 with its main reservoir, Lake Hennessey in the mountains east of Rutherford, 84 percent full. City Water General Manager Joy Eldredge said even a below-normal rain year could fill the reservoir by next summer.
“It’s a solid position to be in at the end of the dry season,” Eldredge said.
Massive Lake Berryessa in eastern Napa County will be harder to fill. The federal reservoir that provides Solano County cities and farms with water and serves as a Napa County recreation draw is at 53 percent of capacity.
Lake Berryessa was last at capacity more than a decade ago. The federal Capell Cove public boat launch closed Aug. 8 because receding water levels no longer reached the ramp.
Filling Lake Berryessa would take about 800,000 acre-feet of water draining into the lake, said Roland Sanford of the Solano County Water Agency. That would be enough water to cover all of Napa County, were it flat, to a depth of more than a foot deep.
A lake level rise of that magnitude last happened during the 1994-95 rain year. The city of Napa that year received 41 inches of rain – 41 inches! – compared to an average of about 24 inches. The National Weather Service measures rainfall from July 1 through June 30.
That’s the type of rain year that might be needed to wipe out California’s drought in a matter of months.
But above-normal rains and snowfall would have to extend far to the south of Napa County. Even though Napa has escaped the worst of the drought, Carlson said drought relief must come to hard-hit areas of the state for the state’s drought status to be lifted.
Each year, sports magazines go out on a limb and make predictions about what team will win the World Series and other championships. Weather prognosticators make their own predictions.
So will 2016-17 be more drought or a drought-buster?
Bob Benjamim, a forecaster with the National Weather Service, said neither El Nino nor La Nina conditions exist. Climatologists use these complex conditions related to Pacific Ocean temperatures off the coast of Peru to predict rain seasons.
“We’re expecting normal rainfall,” Benjamin said. “Normal means we’ll have some heavy rains, we’ll have some dry periods.”
Of course, last rain season was widely touted in the media as the Godzilla El Nino season and El Ninos often bring more rain to California. The state prepared for floods that never materialized and the drought continued.
“I think there was a lot of hype,” Benjamin said, adding El Nino doesn’t always have a distinct footprint for some parts of California.
Even water supply experts sometimes have trouble finding a rain season prediction they can trust. Sanford laughed and jokingly mentioned the Farmer’s Almanac.
The Old Farmer’s Almanac, founded in 1792, claims an 80 percent accuracy rate for its predictions. It predicts the Pacific Southwest this winter and spring will see below-normal rainfall and temperatures, with much of the rain falling in late November, mid-December and mid-January.
Whatever happens, Buckland is optimistic that things will turn out OK for Napa County’s vintners. He described Napa Valley’s topography of mountains to the west and east as squeezing rain out of passing storms and talked about low water use in vineyards.
“Even with a lower number of storms, we’re almost always going to get the resources we need,” he said.
Editor's Note: As of 2015, the National Weather Service changed its century-old practice of measuring the "rain year" from July 1 to June 30, to Oct. 1 through Sept. 30. In the interest of historical consistency, the Register compiled last year's total using the old method for this article.