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
 

March Conditions a Key in Determining Summer Water Supply

Boise, ID, March 7, 2008— With heavy snowfall throughout the winter, it may appear that there is plenty of water stored in mountain snowpacks for the year. According to water supply specialists with the Natural Resources Conservation Service (NRCS), however, conditions in March and April may be the key to how much snowmelt actually ends up in Idaho reservoirs and streams this summer.

According to the March 1 Water Supply Outlook Report released by NRCS, snowpacks are 95 to 130 percent of average across the state, and lower elevation snowpacks are up to 200 percent of average in Northern Idaho. Still, experts note that an abundance of summer water is not a sure thing, at least not yet.

“If March is dry like last year,” said NRCS water supply specialist Ron Abramovich, “Idaho's snowpacks would peak at only 80 to100 percent of average in early April.”

Abramovich explains that while current snowpack numbers are encouraging, it is important to remember that snowfall alone does not determine the year’s water supply. Spring and summer streamflows are dependent upon many factors, such as spring and fall precipitation, soil moisture, groundwater and spring levels, geology, spring air temperatures, and other factors.

“The wild card in this year's water supply picture is how the above-normal low elevation snowpack will melt,” said Abramovich. “A gradual melt will help prime the hydrologic system and give us a fairly steady flow of water over time. Rapid snowmelt could contain the potential for excessive runoff in unregulated basins.”

The Water Supply Outlook Report also includes locally specific data on snowpack, precipitation and reservoir storage. According to the report, February precipitation ranged from only 65 percent of average in the Wood and Lost basins to about 110 percent of average in the Clearwater, Southside Snake basins and Bear River basin. Precipitation for the water year ranges from near average in the Bear, Panhandle and Upper Snake to 115 percent in the across west-central Idaho.

The projections indicate that summer streamflow forecasts range from 68 percent of average for the Bear River at Stewart Dam to 120 percent in the Clearwater basin.

“With current reservoir storage at average or less across the state, this means that average or better precipitation is needed to maintain snowpacks and keep water supply forecasts from decreasing during March,” Abramovich explained.

The full Water Supply Outlook Report, along with additional data on snowpack, precipitation, reservoir storage and projected streamflow, is available on the NRCS Snow Web site at:  http://www.id.nrcs.usda.gov/snow/

NRCS provides voluntary technical and financial assistance to people interested in protecting and enhancing soil, water, and related natural resources on non-federal lands. NRCS staffs work in every county in the state and directly assist farmers, ranchers, and others. NRCS, an agency of the U.S. Department of Agriculture, is an equal opportunity provider and employer. Local contact information is located in the telephone book under the federal government listing or can be found online at: www.id.nrcs.usda.gov.

USDA is an equal opportunity provider and employer.

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