NEWS

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

SNOWPACK IS GOOD BUT MORE IS NEEDED

BOISE, JAN.15—Next summer’s water supply is still uncertain in spite of snowpacks that range from 85 to 160 percent of average for most basins in the state, according to the Idaho water supply outlook report issued Jan. 1 by the Natural Resources Conservation Service. The amount of snow that has fallen so far this year is only 35 to 65 percent of the April 1 seasonal peak. With more than half the winter still to come, no one can say Idaho’s drought is over.

 December precipitation ranged from near normal in northern Idaho to almost twice normal across southern Idaho, especially in the low elevation snow zones. Reservoir storage remains low, with the Jan. 1 combined storage for 21 reservoirs and lakes the third lowest since 1958. The lowest years were 1992 and 1994 which also followed severe drought years.

 Streamflows remain low, which is normal for this time of year. The most probably forecasts range from 70 to 110 percent of average. The lowest forecasts are in the main stem Snake River-American Falls inflow, Blackfoot Reservoir inflow, Snake River at King Hill and near Murphy at about 70 percent of average. The highest forecast is for Owyhee Reservoir inflow at 110 percent of average.

 NRCS monitors the snowpack during the accumulation and melt phase. The data and runoff forecasts are coordinated with the National Weather Service. Updated information on water supplies can be found on the NRCS snow survey web site at http:/idsnow.id.nrcs.usda.gov.

Water outlook by basin:

Panhandle region: Precipitation is 117 percent of average, more than twice the amount that fell by this time last year. Snowpack ranges from 86 percent of average in the Pend Oreille basin to 129 percent in the Priest River basin. With more than half the winter still to come, snowpacks need to continue to build in the higher elevations.

Clearwater River basin: Precipitation is above normal at 114 percent of average. Fall rains helped recharge soil moisture, so this is one area of the state that may have a minimal soil moisture deficit. Snowpack in the basin is 97 percent of average. Normal or above normal precipitation is needed for the remaining winter months.

Salmon River basin: Precipitation is 109 percent of average. Snowpack for the basin is 94 percent of average and ranges from 78 percent of average for the Lemhi River basin, one of the lowest percentages in the state, to 115 percent for the Little Salmon River basin, twice the amount from last year. Above normal precipitation is needed for the remaining winter months to ensure a good water year.

Weiser, Payette, Boise River basins: Precipitation is 117 percent of average. Snowpack percentages are the greatest in the low elevation drainages of Mores Creek at 164 percent of average and Mann Creek and Weiser basins at 130 percent. The Middle and North Fork Boise basins snowpack is the lowest at 110 percent of average. The first half of winter looks promising, but much more snow is needed in the second half.

Wood and Lost River basins: Precipitation is 128 percent of average. Snowpack is normal for the Big Wood and Little Wood basins but decreases to 93 percent of average in the Big Lost and 77 percent in the Birch-Medicine Lodge basins. Reservoir storage remains low and ranges from 7 percent full in Magic Reservoir to 34 percent in Mackay Reservoir. More snow is needed in these central Idaho Mountains to satisfy water needs.

Upper Snake River basins: Precipitation is normal at 102 percent of average. Snowpacks are greatest in the low elevation drainages of Blackfoot, Willow and Portneuf basins, ranging from 106 to 115 percent of average. Lowest snowpacks are in the Teton, Snake above Jackson Lake and Salt basins at 82 percent of average. The eight major reservoirs in the upper Snake basins are on-third full or half of normal.

Southside Snake River basins: Precipitation ranges from 110 to 190 percent of average. Snowpack ranges from 145 percent of average in the Salmon Falls and Bruneau basins to 160 percent of average in the Oakley and Owyhee basins. Southern Idaho reservoirs are nearly empty. Salmon Falls Reservoir is the lowest in the state at 5 percent of capacity or 19 percent of average, the lowest Dec. 31 storage reading since 1962. Oakley Reservoir is 13 percent full, 38 percent of average. Owyhee Reservoir is 15 percent full, 26 percent of average.

Bear River basin: Precipitation is just above normal. Reservoir storage remains low with Bear Lake at 40 percent of capacity or 63 percent of average. Montpelier Creek Reservoir is 20 percent of capacity, which is about half of normal.
 

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