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Water year gets a jump start
By Cindy Snyder, The Times-News Online
December 3, 2001
 
BOISE -- Precipitation has been slow to come this water season, but the 2001-02 season finally got the jump start it needed over Thanksgiving. Another round of storms this week pushed the snowpack to above normal levels across southern Idaho.
      While finally seeing white peaks in the mountains is helping lift water users' spirits, hydrologists are quick to point out that one-third of the snow accumulation period is already behind us. If the recent snows are viewed against the amount of snow expected by April 1 -- the traditional ending point of the snow accumulation period -- the snow that has fallen ranges from just 15 percent of the peak for the Snake above Palisades to a high of 21 percent of the peak in the Bruneau basin.
      Ron Abramovich uses Morris Creek above Idaho Falls as an example. That Snotel site reported 5 inches of snow water on Nov. 28, the site normally peaks at 35 inches on April 1.
      "There's still a long ways to go," said the snow forecaster with the USDA-Natural Resources Conservation Service in Boise.
      Storm totals over the Thanksgiving holiday ranged from 10 to 30 inches of snow. If that snow were melted it would equal 1 to 3 inches of snow water. That was enough to push snow water content across the state from 5 to 30 percent of average before Thanksgiving to 50 to 90 percent of average on November 26, Abramovich said. Another 8 to 16 inches of snow fell on Wednesday, Nov. 28.
      Before the Thanksgiving storms, only the Panhandle was above normal in terms of total precipitation. Fifteen inches of precipitation in October and early November tremendously helped that region, which was one of the driest in the state last year. Last week's storms did not bring much additional snow to that area, although the storms helped move southern Idaho from the parched category to merely thirsty.
      Basins on the south side of the Snake River benefited the most from Wednesday's storm. The Salmon Falls Creek basin jumped from 7 percent of normal snow water before Thanksgiving to 91 percent on Nov. 28 to 110 percent on Nov. 29. Snotel sites north of the river did not show the same dramatic improvement from Wednesday's storm, but Abramovich says that may be a matter of timing. Snotel sites report as of midnight, if the storms didn't reach those sites until later in the evening, they wouldn't report as much improvement.
      Nonetheless, the Big and Little Wood basin improved from 30 percent of normal snow water before Thanksgiving to 51 percent of normal on the 28th to 74 percent on the 29th. Irrigators watching the Upper Snake River basins didn't see a dramatic improvement, moving from 43 to 67 to 68 percent of normal on the same days.
      Although the short-term forecast is for several wet weeks in a row, the long-term forecast remains stubbornly neutral. Abramovich said the December-to-February long-term weather forecast for Idaho and the Pacific Northwest is for "climatology," which means there is an equal chance of below normal, normal, or above normal precipitation.
      Forecasters are unable to discern significant La Nina or El Nino signatures in the Pacific Ocean, which has hampered snow predictions in a year when having at least normal snowpack is critical for the next irrigation season.
      Irrigators were blessed with good early snowpack last year, which dried up as the water year progressed.
      "Hopefully that won't happen this year," Abramovich said of the outcome.
      As of Nov. 29, 2000, snow water amounts ranged from 65 percent of normal for the Snake above Palisades to 139 percent of normal for the Salmon Falls Creek basin.
      Near normal snowpacks and streamflow volumes are needed across the state this winter to provide adequate water supplies next year, Abramovich said. Several years of above normal winter and spring precipitation are needed to recharge soil moisture, fill reservoirs and provide good future carry-over.
      The lowest storage as of Oct. 31 was in the Magic, Little Wood, Mackay, Oakley and Salmon Falls reservoirs, which were nearly empty at 3 to 8 percent of capacity. Other reservoirs range from 19 percent of capacity for the 8 major reservoirs in the Upper Snake to 75 percent of capacity in the Panhandle region.