Tuesday, March 9, 2010
Lack of Winter Snowfall Puts a Damper on Idaho'w Water Supply
Mark Trupp Photo
Snow survey data collected last week across Idaho by the natural Resources Conservation service show February continued this winter’s trend of below normal precipitation. Near record low winter precipitation has resulted in meager snow packs across the state that range from 55 to 75% of average.
“The highest snow packs are along the State’s western and southern edges since they are affected by the major storms hitting the southwestern states,” said Ron Abramovich, Water Supply specialist for NRCS. “That’s the El Nino weather pattern – where the southwest gets above average snowfall and the Pacific Northwest is dry.”
Idaho’s water supply comes from mountain snow packs. The majority of reservoir inflows come from snow packs above 6,000 in southern Idaho and above 4,500 feet in northern Idaho. Given the low snow packs, runoff will be below normal across the state and irrigation water shortages are predicted in many central, southern and eastern Idaho basins.
Two long-term snow measuring stations in the Upper Snake Basin in Yellowstone National Park are the 3rd lowest since records start in 1919. The snow pack in this area affects water supply in eastern Idaho.
“February’s mountain precipitation was ranged from 30-55% of average, adding to below average amount for November, December and January,” said Abramovich. “Because of the low precipitation amounts, stream flow forecasts decreased from February predictions.”
Most reservoirs across the state are storing above average amounts for March 1. However, with well below average stream flow predicted for this summer, irrigation demand will draw down reservoirs to their minimal storage levels by summer’s end and greatly increase the need for good snow next winter.”
“One last hope to salvage this year’s water supply would be to receive a cool and wet spring,” Abramovich added. “Above average precipitation and cool temperatures in April and May would delay snow melt, keeping the snowpack in the high country longer.”
For a summary of water supply outlook by region, follow the link below: