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U.S. Department of Agriculture
Natural Resources Conservation Service
9173 W. Barnes Dr., Suite B
Boise, Idaho 83709

For more information:
Ron Abramovich 378-5741


WATER FORECASTS LOOK ENCOURAGING, BUT MORE SNOW IS NEEDED

BOISE, ID— Overall, Idaho water supply forecasts look encouraging according to the Idaho Water Supply Outlook Report issued Feb. 1 by the Natural Resources Conservation Service (NRCS).

The water spigot was either on or off during January," says Ron Abramovich, NRCS water supply specialist in Boise. January started with a series of storms giving way to nearly two weeks of high pressure. Another series of storms at month's end allowed Idaho's snowpack to remain near average on February 1.

Snowpack conditions and streamflow forecasts are near average in most basins. “This year's snowpack will provide some short term relief from the drought,” Abramovich stated. “But long term dryness will remain across southern Idaho until several wet snow years in a row put moisture back into the ground, springs, wetlands and aquifer."

Idaho's snowpacks range from 95 to 110 percent of average for most basins. The lowest snowpacks are 90 percent of average in the Bear, Little Lost, Birch, Big Wood above Hailey, Lemhi and upper Salmon basins. The highest snowpack is 145 percent of average in the Owyhee basin.

Streamflow forecasts call for 90 to 110 percent for most streams. The highest forecasts are in the Owyhee basin at 110-140 percent of average. The lowest is Bear River in southeastern Idaho at 13 percent of average. If current weather trends in the Bear River basin continue the most severe water shortages since the 1930s are likely. Irrigation shortages are possible in the Salmon Falls, Oakley, Big Wood, Big Lost, Little Lost and parts of upper Snake especially if future conditions are drier than normal. “Users may wish to use a lesser forecast,” Abramovich says. “The accumulative drought effects from the last four years may still impact final numbers.”

The following lists the water supply outlook for specific regions:

  • Panhandle region—snowpacks are average, streamflow forecasts call for 95-105 percent of average.
  • Clearwater River basin—snowpack is 109 percent of average, streamflow forecasts range from 95-110 percent of average.
  • Salmon River basin—snowpack is 99 percent of average, streamflow forecasts are 73 percent for the Lemhi River, 86 percent for the Middle Fork Salmon River and 99 percent for the Salmon River at White Bird.
  • Weiser, Payette, Boise River basins—snowpacks range from 105-115 percent of average with some mid-elevation snow measuring sites at 130 percent of average, streamflow forecasts range from 90 percent for the South Fork Boise River to 109 percent for Mores Creek. Payette and Weiser rivers are forecast at average.
  • Wood and Lost River basins—snowpacks range from 90-105 percent of average, streamflow forecasts call for 80-90 percent of average, except for the Little Lost River forecast at 62 percent of average.
  • Upper Snake River basin—January precipitation was 83 percent of average, snowpacks range from 90-120 percent of average, streamflow forecasts call for 90-110 percent of average.
  • Southside Snake River—snowpacks range from 115-145 percent of average, streamflow forecasts range from 94 percent for Salmon Falls Creek and Oakley Reservoir inflow to 145 percent in the Owyhee River headwaters. There is a well above average snowpack in the Owyhee basin with some measuring sites at 2 to 3 times their normal February 1 amounts.
  • Bear River basin—snowpack is 90 percent of average in the Bear River, streamflow forecasts are for 75 percent in the headwaters and decrease to only 13 percent at Bear Lake. This decreasing streamflow volume relationship is similar to last year's observed runoff and is a result of the accumulative drought effects, dry soils, springs and wetland areas. Streamflow in the lower Bear River was less than 10 percent of average each of the last three years. Bear Lake is only 10 percent full. Irrigation shortages are likely and supplies may run out by mid-July. Conditions can improve with two more months of winter still to come, but usually several wet years are needed to saturate the soils and improve the snowmelt runoff efficiency.

The complete February 1, 2004 Idaho Water Supply Outlook Report is available on line at:

http://www.id.nrcs.usda.gov/snow/watersupply/

In addition, the NRCS is developing a Drought and Surface Water Supply Index web page at:

http://www.id.nrcs.usda.gov/snow/watersupply/swsi-main.html

Numerous graphs will be available to keep users aware of current, historic and water supply trends in their basin of interest.


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