NEWS

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

For more information:
Phil Morrisey 378-5741

MORE SNOW NEEDED TO INCREASE IDAHO WATER SUPPLIES

BOISE, FEB. 11, 2003—The odds of recovering to near normal or better snowpack levels by April 1 are slim, according to the Idaho Water Supply Outlook issued Feb. 1 by the Natural Resources Conservation Service. Snowpacks range from 40 to 65 percent of their April 1 seasonal snow water content peaks, with only 40 percent of the winter still to come.

Warm temperatures in January resulted in rain at elevations above 7,000 feet and an increase in streamflow. But what the state needs is precipitation in the form of snow that remains in the mountains to melt in the spring and summer, which will keep streams running higher when consumptive use and demand are greatest and monthly precipitation amounts are the least.

The lowest snowpacks in the state are about half of normal in the Coeur d’Alene, St. Joe and Oakley basins. Next lowest are 55 to 65 percent of average in the Bear River, Raft, Portneuf, Salmon Falls, Bruneau, Owyhee, and North Fork Clearwater basins. The highest snowpacks are in the Little Wood and Big Lost basins at 105 percent of average.

According to Ron Abramovich, NRCS water supply specialist, snow data for several basins across the state indicate that when Feb. 1 snowpack is below average, snow returned to near normal or better by April 1 only about 4 out of 25 years. Only 1 of those 4 years, 1983, was an El Nino year like this year.

Most streamflow forecasts decreased from last month. The highest forecasts call for near normal runoff in the Big Lost River basin. The lowest forecasts are in the Bear River basin at 32 percent of average. Across southern Idaho, streams are forecast for 40 to 50 percent of average for Oakley Reservoir, Salmon Falls, and Owyhee. Upper Snake River streams are forecast at 60 to 80 percent of average.

The January rain gave reservoir storage a boost. All reservoirs and lakes from Cascade Reservoir north are now storing average or above storage levels. The Boise reservoir system increased from 33 percent to 38 percent of capacity and is about the same as a year ago. The Owyhee Reservoir came up from 16 to 20 percent of capacity. Elsewhere in the state, reservoirs are 25 to 65 percent of average.

The Natural Resources Conservation Service coordinates the cooperative Snow Survey Program and provides water supply forecasts. NRCS gathers data through a network of 76 automated SNOTEL (SNOw TELemetry) sites and 100 manually measured snow courses. The latest information is available at http//www.id.usda.gov/snow.

Water supply outlook by basin

Panhandle Region: Streamflow forecasts decreased from last month and now range from 55 to 85 percent of average. Water users should plan for below normal runoff volumes this summer.

Clearwater River Basin: Spring and summer streamflow forecasts decreased from last month and call for 77 percent of average for the Selway and Lochsa Rivers and 66% for Dworshak Reservoir inflow and Clearwater River at Spalding.

Salmon River Basin: Streamflow forecasts are for 85 percent of average for the Salmon River above Salmon and 86 percent for the Salmon River at White Bird.

Weiser, Payette, Boise River Basins: Streamflow forecasts decreased from a month ago and now range from 80 to 90 percent of average runoff. Streamflow runoff greater than 65 percent of average is needed to provide adequate irrigation water in the Boise basin.

Wood and Lost River Basins: Streamflow forecasts decreased from a month ago and now range from 85 to 100 percent of average except for Camas Creek and Little Lost River at 66 percent of average. Water users who rely on Magic or Mackay irrigation water should anticipate water shortages if future precipitation is below normal.

Upper Snake River Basin: The Snake River near Heise is forecast at 75 percent of average and the Henry’s Fork near Rexburg at 59 percent. Streamflow in the 80 to 90 percent of average range at Snake River near Heise is needed to provide adequate irrigation water supplies.

Southside Snake River Basin: Streamflow forecasts decreased considerably from last month and now call for 40 to 50 percent of average. Irrigation water shortages are expected.

Bear River Basin: Streamflow forecasts are the lowest in the state, at a meager 32 percent of average for the Bear River below Stewart Dam. Water users should prepare for very low runoff volumes for the third year in a row, especially if future precipitation is below average.

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