Should dry conditions persist, Turlock Irrigation District is expecting a third consecutive drought year and an irrigation allotment to match.
TID hydrologist Olivia Cramer on Tuesday said that despite the 10th of an inch of rainfall which fell in the Tuolumne River Watershed Monday night — with a splattering of sprinkles locally — the current water year has seen just 18.76 inches of rainfall so far. That’s 79.2 percent of average for the date and above totals seen at this point last year, Cramer said, but anticipated dry conditions moving forward spell continued drought.
The rainfall earlier in the week broke a 45-day dry spell, Cramer said.
“It was nothing significant, but still, something is better than nothing,” she said.
Heavy storms in October and December have kept the current water year from reaching devastatingly low levels, and the 16-day forecast currently predicts about just under an inch of rainfall coming.
So, why are conditions so dry?
According to Cramer, there hasn’t been enough moisture in the air to create any atmospheric rivers — storm events which the region typically relies on to create much of its precipitation. There won’t be any significant events for some time, she added, as all 22 models used to measure moisture show conditions will remain dry.
“When we don’t see any kind of moisture driving those events, it does give us cause for concern,” Cramer said.
If the dry conditions continue, as TID predicts, the water year will end up at about 53 percent of normal. Last year’s water year was 32 percent of normal, and 2020 ended up at about 51 percent. For comparison, the last three consecutive years of drought from 2012 to 2014 featured water years of 48 percent, 59 percent and 33 percent, respectively.
In 2014, Don Pedro’s elevation was about 740 feet and featured TID’s lowest irrigation allotment of 18 inches. This year, the previous fall and winter storms have helped Don Pedro to sit at 749.8 feet.
On Tuesday, TID water distribution department manager Mike Kavarian proposed an 18-inch to 24-inch irrigation allotment, with a 182-day irrigation season from April 7 to Oct. 5. Those numbers are based on dry conditions persisting, he said, and could change by the time the TID Board of Directors approves the irrigation season on March 22.
“We’re trying to be as conservative as possible,” TID general manager Michell Reimers said. “...We haven’t seen this dry of January and February before, so it might seem a little extreme.”