Rain vs. Snow

Warm, dry conditions dominated the March weather scene in Idaho. Above normal temperatures combined with well below normal precipitation induced major declines in the mountainous snowpack and greatly increased the probability of water shortages in Idaho this summer.

“March’s snow water content typically increases during the month, but not this year,” said Ron Abramovich, NRCS Water Supply Specialist. “As a result, irrigation water shortages are expected across many of Idaho’s central and southern basins.” 

Several basins across the state showed substantial decreases in snowpack or melted out well in advance of their typical dates. Declines of 20 to 30 percent were common across southern Idaho, with central Idaho basins from Weiser to the Mud Lake area taking the hardest hit. Of the 137 SNOTEL sites statewide, only 30 sites reported net snow accumulation in March. Several basins in the Upper Snake have snowpacks at approximately 90 percent, but almost half of basins across Idaho are at 50 percent or less of median.

Reservoir levels also varied greatly across the state, ranging from 19 to 99 percent full.  With the warm, dry spring, crops are requiring water now and natural precipitation is not meeting early growing season needs. If reservoirs are drafted early to meet irrigation demands, many will likely reach their minimal storage levels before summer’s end.

Streamflow forecasts have continued to decline for the third consecutive month.  Flows in the Big Lost, Little Wood, Big Wood, Coeur d’Alene, Owyhee and Bear basins are forecast to be near record lows.  The highest streamflow forecasts are 80 to 90 percent of average in the northern Panhandle and Montana rivers flowing into Idaho (the Selway River and three Upper Snake tributaries, Pacific Creek, Buffalo Fork, and Greys).  

Above normal summer temperatures are expected, and the meager mountain snow that remains will not sustain flows in most of Idaho’s streams for long.  Pull out your hiking shoes, fishing poles, bikes, and boats and get ready to take advantage of Idaho’s many outdoor recreational opportunities a little early this year.