NEWS

United States Department of Agriculture
Natural Resources Conservation Service
9173 W. Barnes Dr., Suite C
Boise, Idaho 83709
 
For More Information:

Ron Abramovich, 208/378-5741
Phil Morrisey, 208/685-6983
 

How the Snow Melts Depends on Spring Weather
April Water Supply Outlook Report for Idaho Now Available Online

Boise, ID, April 8, 2008— Water managers, irrigators, and other water supply watchers are paying keen attention to weather patterns this spring, looking for any indication of how fast this year’s significant mountain snowpacks will melt. While spring weather and its effects can be variable, hydrologists with the Natural Resources Conservation Service (NRCS) in Idaho say this year’s healthy snowpacks are likely to fill most reservoirs in the state and provide adequate water supplies for the summer. NRCS released the latest water supply data for Idaho this week in the April Water Supply Outlook Report. 

“Current snowpacks point to healthy streamflows and reservoir storage for the summer,” said NRCS water supply specialist Ron Abramovich, “but we are still waiting to see how spring temperatures and precipitation will affect the melt season.”

According to the NRCS report, current water storage in Idaho reservoirs ranges from 70 to 110 percent of average to 30 to 60 percent of average for Magic, Little Wood, Blackfoot, Salmon Falls, Owyhee and Bear Lake. Water supplies may be tight in the Little Lost and Big Wood basins. Spring temperatures and precipitation are the key factors in determining snowmelt rates and when peak streamflows will occur this spring. Water managers will be watching the weather and water levels to determine if reservoir releases are required to reduce flood risks while ensuring adequate storage for the coming year.

Warm temperatures in early March melted some of the low elevation snow without producing major runoff events. However, low temperatures across the Pacific Northwest later in the month halted melting and allowed more snow accumulation across the state, adding to the already high snow levels in northern Idaho. In addition, mid-elevation snow along Idaho's western border is well above average and ready to melt with the onset of warmer temperatures.

Statewide, current snowpacks are mostly above average, but they do vary. The highest snowpack percentages are in the lower drainages of the Rathdrum and Palouse basins, measuring at 165 percent of average, while the lowest are 90 to 99 percent of average in the Middle and North Fork Boise, Big Wood above Hailey, Little Wood, Big Lost, Hoback (WY), and most of the Bear River tributaries.

Summer streamflows in the Panhandle, Clearwater and Weiser basins are forecast at 115 to 125 percent of average. The rest of the region is forecast at 90 to 115 percent of average, except the Bear River at Stewart Dam which is forecast at 58 percent of average.

The full NRCS Water Supply Forecast Report for April can be viewed online at: http://www.id.nrcs.usda.gov/snow/watersupply/. The report provides a summary of snowpack conditions, precipitation, reservoir storage, and forecasted streamflows at monitoring points in each major basin in the state.

SPECIAL AUDIO FEATURE:  The water stemming from winter mountain snowpack runoff is important to the Western way of life. On this edition of "Agriculture USA," Rod Bain looks at the impact this year's snowpack could make on what has been many years of drought in the West. Features USDA’s Rod Bain and Meteorologist Brad Rippey. Access the MP3 audio format from the USDA Broadcast and Media and Technology Center by searches at:  http://audioarchives.oc.usda.gov/radnewsfeatarchive.asp (CD# 14.08 THE IMPORTANCE OF THE WESTERN SNOWPACK, 4/1/08)

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