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April 8, 2016

THE DROUGHT: So Is It Over?

On March 13, 2016, after several days of heavy rains, especially in Northern California, 103,576 acre feet of water flowered into the Lake Oroville reservoir, which is about 80 miles north of Sacramento.  That was the most acre-feet that Lake Oroville had collected in a single day since February 2, 2004.

The next day was even better.  On March 14, 2016, the lake collected 107,740 acre feet, which was even better than that February day 12 years ago.  Doug Carlson, a spokesman for the California Department of Water Resources (DWR), said on March 15 he had not yet had time to see how many years back he would have to go to find a better day than that.  He said a better two-day total than the more than 211,000 acre feet produced on March 13-14 would be very hard to top.

On that same day, the eight Northern California weather stations that DWR operates revealed that rainfall for the year, as of March 15, was 130 percent of normal for that date and 99 percent of the average rainfall in any given year.  A storm in the Pacific Ocean was expected to hit within a week allowing at least Northern California on April 1 to be certain of a precipitation year greater than average.  Typically the state collects more than 15 percent of its annual rain after that date so it is quite possible that the year is going to end up significantly above average.

So the drought is over, right?

Not so fast, said Carlson.  There is no hard and fast rule as to when a drought can be declared over.  It is not the amount of rain that ends the drought, but rather the cessation of impact from the drought.  Though California’s northern reservoirs had very good numbers in March and appeared to be headed for above-average readings when May 1 comes around, the same thing cannot be said for Southern California and the Central Valley.

Lake Perris in Southern California was sitting at 41 percent of normal on March 15, with its neighbor Castaic Lake even lower.  New Melones Lake, in the eastern foothills at the north end of the San Joaquin Valley was only 23 percent full in mid-March.  “Those areas are still feeling the impact of drought,” Carlson said.  “By May 1, I think we will have a much clearer picture of whether the drought is over and policy makers feel comfortable saying that.”

It does seem certain—and already has been announced—that some of the water use restrictions that have been imposed over the past four years will be relaxed.  Both the state and federal water projects will certainly deliver a higher percentage of contracted water than they have the past four years.  Of course, that won’t be difficult as zero percent was the allocation for the past two years for many users.  In mid-March, the number stood at 30 percent, without counting the water collected from the previous storm.  Carlson said the water projects were due for an update on allocation and most people expected an increase.

The El Niño itself gets mixed reviews this year.  It certainly did not perform as advertised, as experts predicted that very heavy rains in Southern California were a 95 percent certainty.  Northern California had a better than 50/50 chance to get above average rains and it appears to have cleared that hurdle and probably quite easily.  But those experts did not have a lot of El Niño-like years on which to base their projections.

Carlson paraphrased the state’s climatologist, Mike Anderson, as saying the El Niño conditions over the past 50 years have produced mixed results.  Hence it was not unreasonable that this year has not followed the predicted pattern.

It can be said with certainty that while the impact from the drought might still linger in many areas, statewide, California did not experience a fifth year of drought with regard to precipitation.  The drought map has far fewer brown areas than it did a year ago.

And as this is being written on March 15, Carlson reminded that long range forecasting is still only accurate about two weeks out.  There is still the chance that April and May storms may bring more drought relief.