The 2021 water year ended on Sept. 30, and in the words of one hydrologist: “Good riddance!”
Utah and much of the West have been racked by a historic drought, and Jordan Clayton, who supervises the Utah Snow Survey for the U.S. Natural Resources Conservation Service, said there have been recent signs of progress, though real drought recovery is dependent on this winter’s snowfall.
He said conditions are primed for more snowmelt to reach the state’s reservoirs in the spring if more snow does arrive. The soil is holding moisture heading into the winter, meaning it won’t soak up the runoff the way it did last spring.
“Because of recent storms and because of excellent monsoons in August, we’re set up, anyway, for a better runoff season,” he said. “None of that’s going to matter if we don’t get good snow.”
Clayton estimated the state has a precipitation deficit of 11 inches, meaning 11 more inches of precipitation is necessary compared to normal levels for the state to recover.
That’s a measure of the actual liquid in the precipitation, and can’t be made up with a foot of snow.
Still, there are positive signs.
“The 11 inches of water deficit — that was 13 inches at the end of the water year in September,” he said. “We’re definitely making progress.”
Clayton called the lack of precipitation in the 2021 water year “extraordinary.” With little moisture last fall, soils were bone-dry as winter approached. A below-average snowpack was then mostly absorbed into the ground instead of percolating through the state’s rivers and into its reservoirs.
“Essentially, you have to fill up that bucket first,” he said of the soils. “Once you fill up that bucket, you’re in a good place to have a much more efficient runoff.”
In June, the general manager of the Weber Basin Water Conservancy District, which oversees many of the water systems in Summit County, said the district stored around 7,000 acre-feet of water from snowmelt as opposed to the 220,000 acre-feet it receives in an average year.
That’s 3%.
According to a water-year-end report from the Natural Resources Conservation Service, “reservoir storage ended the water year at 48% of capacity, down 15% from last year and down 26% from the previous year at this time.”
It appears that the same situation won’t repeat itself this year, with the ground absorbing crucial portions of the snowmelt. Evapotranspiration levels — the amount of water that leaves soils and plants and goes into the air — are lower in the fall as the days get shorter and temperatures drop, according to the report. In late September, soil moisture levels were hovering around average. Subsequent storms have pushed the soil moisture levels to above average, Clayton said.
“The soil moisture does tend to get locked in from what the conditions before the snow starts to accumulate and tends to stay at that level through the winter,” he said.
Before the summer rains, the state was at or below the previous record minimum for much of the water year. The monsoons pushed totals to barely above the bottom 10th percentile of observed years and left the state needing to accumulate 13 additional inches of precipitation, according to the year-end report.
“For context, the average annual statewide precipitation is 32.1 (inches), so our current deficit is roughly 40% of what Utah normally gets in a year,” the late September report states.
Luckily, it has started raining since then. And snowing.
That’s made a dent in the amount of water the state needs — making up about 15% of the deficit. But it all comes down to this winter: Officials have said the state receives 95% of its precipitation from snowfall.