February shaped up as one for the record books as far as snow totals in Idaho, according to a report from the Natural Resources Conservation Service.
More snow fell and accumulated last month in Idaho’s central mountains than had fallen in the previous three months, according to Ron Abramovich, water supply specialist for the conservation service.
“Colder than normal temperatures brought light, dry snow that produced impressive snow depth, but not as much snow water equivalent as one might imagine,” Abramovich wrote.
Many snow measuring sites across central and southern Idaho had their greatest, or second-greatest, increase in snow depth and snow water equivalent for the period of record, he said. Both Banner Summit, 7,400 feet on Idaho Highway 21, and Vienna Mine, at 8,960 feet and above Galena Summit, increased from about 50 inches of snow on the ground on Feb. 1 to about 105 inches on March 1 and received an estimated 150 inches of snow in February.
The majority of basins south of the Salmon basin are above or near their seasonal snow water equivalent peaks, with half of March left to go. The snow survey data was gathered on March 1. It showed the Little Wood basin at 117 percent of its seasonal peak.
In terms of precipitation, the big winner was the Little Wood Basin, with more than four times the normal amount of precipitation. The Little Wood basin registered 395 percent of normal precipitation last month. The Big Lost basin was close behind at 375 percent of normal. The Big Wood and Little Lost basins received between 260 and 325 percent of normal precipitation in February, according to the report.
The pattern fits with a typical El Nino weather pattern, he said, which finds drier conditions in north Idaho, while southern Idaho is wetter.
“Streamflow forecasts mirrored the weather and shot up like a good month on the stock market,” Abramovich said. Forecasts range from just above average in northern Idaho to more than 175 percent of average in the Lost and Wood basins. No water supply shortages are expected in Idaho this year. Because of that, Abramovich says wise water management to mitigate floods, ensure reservoirs refill at the end of the high-water runoff season and accomplish aquifer recharge are all keys to a successful runoff and storage season in Idaho.
Many reservoir operators are already on standby to determine when to make releases, Abramovich said. Water releases began from the Little Wood Reservoir in mid-February and continue because of the snowpack that is 160 percent of median above the reservoir.
Mackay Reservoir is still increasing from the good spring flows from the past couple of years and is now 79 percent full, which is 120 percent of average. Releases are expected at Mackay, according to Abramovich, because snowpack is 145 percent of median and streamflow forecasts are predicted to be at 147 percent of average.
Blackfoot Reservoir is 80 percent full, 149 percent of average, and expected to fill this year. Little Wood Reservoir is 60 percent full, 103 percent of normal, and Magic Reservoir is 46 percent full, 122 percent of average.
The Salmon River basin received more than 200 percent of average precipitation in February, pushing the water year-to-date precipitation to 108 percent of normal, Abramovich reported. The March 1 snowpack reading showed the basin at 120 percent of normal, ranging from around 100 percent of normal on the eastern edge to 182 percent of normal on the southwestern edge.
Nearly every site in the Salmon River basin received more than 200 percent of normal snow water equivalent accumulation for February, Abramovich said. Streamflow forecasts for the Salmon basin are at 110 to 120 percent of normal.
In the Wood and Lost basins, areas below 7,000 feet elevation set widespread records for snowpack increases, Abramovich’s report states. The Big Lost basin snowpack total is 145 percent of normal, while the Little Wood is at 160 percent of normal.