NEWS

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
Phil Morrisey 378-5741
 

MOST IDAHO SNOWPACKS BELOW NORMAL

BOISE, JAN. 10, 2003—Winter storms during the last week of December brought much needed snow and valley rains to much of Idaho, but most basin snowpacks are still well below seasonal average. Precipitation in northern and southeastern Idaho is only 72 percent of average, according to the Idaho Water Supply Outlook Report issued Jan. 1 by the Natural Resources Conservation Service.

As a result of the dry fall and late start for winter, precipitation for the 2003 water year is below normal across the state, ranging from 62 percent of average in the Clearwater basin to 94 percent in the Wood and Lost River Basins.

Combined storage for the state’s 21 reservoirs and lakes is the fourth lowest since 1958. Priest Lake and Dworshak Reservoir are storing the most water at near normal levels. The Payette River reservoir system is 89 percent of average. The Boise River reservoir system is 59 percent of average. Magic Reservoir remains nearly empty for the second December in a row at only 8 percent of capacity. Mackay Reservoir is 23 percent of capacity, 42 percent of average and the fifth lowest Dec. 31 storage out of 78 years. The combined reservoir storage for the 7 major reservoirs in the upper Snake River basin is 26 percent of capacity, just slightly better than a year ago. Bear Lake has the ninth lowest Dec. storage since 1922.

Dry soils and lack of fall precipitation kept Idaho streams low this fall, with some at or near record low levels in early November.

Streamflow forecasts range from 45 percent of average in the Bear River basin to normal volumes in the central mountains.

The mid-point of the October-April snowpack recharge season is quickly approaching. Many areas throughout the state need to start receiving heavier and more regular precipitation soon to avoid water shortages next summer.

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.nrcs.usda.gov/snow.

Water Supply Outlook by Region

Panhandle: Snowpacks are 50 to 60 percent of average in the Coeur d’Alene, St. Joe and Spokane basins, 84 percent in the Moyie basin, and 100 percent in the Priest basin. Streamflow forecasts range from 60 to 85 percent of average.

Clearwater River Basin: Snowpack percentages are nearly the lowest in the state, ranging from 59 percent of average in the North Fork Clearwater basin to 75 percent of average in the Selway basin. Overall, the basin snowpack is 61 percent of average. Streamflow forecasts for Selway River is at 71 percent of average, Lochsa River at 66 percent, and Dworshak Reservoir inflow at 71 percent.

Salmon River Basin: Snowpack is the highest in the Little Salmon and South Fork Salmon basins at 110 percent of average. Middle Fork Salmon River is 91 percent. The Lemhi River is 65 percent. Streamflow forecasts are for 88 percent of average for the Salmon River above Salmon and 89 percent for the Salmon River at White Bird.

Weiser, Payette, Boise River Basins: Snowpacks are near normal in these basins, but based on previous years of monitoring soil moisture, the dry soils under the snow will absorb three to five inches of water when the snow melts. Streamflow forecasts range from 85 to 100 percent of average.

Wood and Lost River Basins: The best snowpacks in the state are in these central Idaho mountains, ranging from 115 to 150 percent of average. Streamflow forecasts range from 105 to 110 percent of average, with the exception of the Little Lost River at 80 percent.

Upper Snake River Basin: Snowpacks range from 70 to 85 percent of average. Streamflow forecasts range from 653 to 83 percent of average. Snake River near Heise is forecast at 81 percent of average.

Southside Snake River Basins: Snowpacks increase from east to west with the Raft and Oakley basins at 72 percent of average, Salmon Falls at 79 percent, Bruneau basin at 91 percent, and Owyhee basin at 98 percent. Streamflow forecasts range from 55 to 75 percent of average.

Bear River Basin: Snowpack ranges from 65 to 85 percent of average. The lowest streamflow forecasts in the state are in this basin at 41 percent of average for the Bear River at Stewart Dam.

Records set

Deadwood Summit SNOTEL site, located in the middle of Idaho, had its biggest snow dump since Feb. 1999. It increased from 11.5 inches of snow water on Dec. 26 to 19.4 inches on Jan. 1. Snow depths increased from 50 inches to 88 inches.

Combined storage for Idaho’s 21 reservoirs and lakes is the fourth lowest since 1958 (Dec. 1991, 1994 and 2002 had less in storage).

Magic Reservoir remains nearly empty for the second December in a row at only 8% of capacity.

Combined reservoir storage in Palisades Reservoir and Jackson Lake is the fourth lowest Dec. 31 combined storage since 1957.

Bear Lake has the ninth lowest December storage since 1922.

Lowest streamflow forecast in the state is 42 percent of average for the Bear River at Stewart Dam.

The Bruneau River Oct.-Dec. total flow was the fourth lowest since 1944 (1990, 1992 and 2002 had less flow than this year).

In the Salmon River basin, December precipitation was 117 percent of average, first time since Dec. 2001 that the basin received above normal monthly precipitation.

December precipitation in the Weiser, Payette, and Boise River Basins was 145 percent of average, first time in a year with above normal precipitation.

Magic Reservoir remains nearly empty for the second December in a row at only 8 percent of capacity, 19 percent of average.

Mackay Reservoir is 23% of capacity, 42% of average, fifth lowest Dec. 31 out of 78 years. Only the Dust Bowl years during the mid-1930s had less water than this year.

Combined reservoir storage in Palisades Reservoir and Jackson Lake is about 100,000 acre feet more than a year ago but is the fourth lowest Dec. 31 combined storage since 1957 (Dec. 1988, 1992 and 2002 had less storage than this year).

Bruneau River Oct.-Dec. total flow was the fourth lowest since 1944 (l990, 1992 and 2002 had less flow than this year).

Salmon Falls Creek Oct.-Dec. flows was the tenth lowest since 1911.

1999 was the last water year with above normal precipitation for the Bear River basin.

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