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Hemlock Butte SNOTEL March 2008 Clearwater Basin
2008 Forecasts: Over, Under and Right On, and Amount of Snow Needed in 2009 for Adequate Surface Irrigation Supplies
Idaho Climate and Water Resource Forecasts for the 2009 Water Year
Sponsored by: Climatic Impacts Group and the Idaho Department of Water Resources October 16, 2008
• Ron Abramovich, Hydrologist, Water Supply Specialist• USDA Natural Resources Conservation Service• Snow Survey Office Boise Idaho • http://www.id.nrcs.usda.gov/snow/
• 2008 water year precipitation 106% of average
• Record high low elevation snow, but not higher elevations
• 2008 water year precipitation 112% of average, highest in state
• April 1 snowpack 125% of average, highest since 1999
• Spring precipitation 99%
• 2008 water year precipitation 95% of average
• April 1 snowpack 109% and May 1 snow 109% as Percent of April 1 Peak
• Spring precipitation 76%
• 2008 water year precipitation 97-105% of average
• April 1 snowpack near average
• Spring precipitation 71-84%
Last year, we said we needed a snowpack > 85% on April 1,Snow was 96% producing 91% of average runoff.
Lost-Wood Divide SNOTEL-- Two Dry Spells:
Prec: Feb-May 6.4” lowest in 26 years, previous low 6.5” in 2007
Jun-Sep 2.5” 4th lowest in 26 years
• 2008 water year precipitation 79-86% of average
• April 1 snowpack 91-107%
• Record low precipitation in Big Lost Basin: Feb-Jul at 22.9 inches, previous record 31.6 inches in 2001 AND Apr-Jun at 37% of average
• 2008 water year precipitation near average
• April 1 snowpack 93-125%
• Apr-Jun precipitation near average, cool temperatures kept snow in higher elevations longer.
Last year, we said we needed an April 1 snowpack > 106% to provide flow > 88%.2008 snow was 105% producing 103% of average runoff.
• 2008 water year precipitation near average
• April 1 snowpack 99-144% of average, but runoff 57- 87%
• Apr-Jun precipitation 80%of average
• 2008 water year precipitation 90% of average
• April 1 snowpack 98%, May 1 83%
•Apr-Jun precipitation 86%of average
Snowpack and Streamflow Needed for 2009 Season
•Analysis is based on September 30, 2008 reservoir storage
•Current storage is projected for March 31, 2009 based on below normal changes due to dry trends
•Required streamflow needed to meet surface water irrigation demand is based on known demand levels from the Surface Water Supply Index (SWSI)
•Snowpack needed for 2009 is determined by looking at years when there was a good snowpack and ‘Worst Case Scenario’ for runoff. Some were:
• in middle of consecutive dry years
• low soil moisture, and / or groundwater levels
• dry spring
• 1989 is Good Example of Poor Runoff Year – snowpack was near average, but runoff was below to much below average due to dry spring and cumulative drought effects.
Questions – Comments – CorrectionsAdditional and more detail information about ‘Amount Needed’ is available on the
Idaho Snow Survey Web Page at: http://www.id.nrcs.usda.gov/snow/
• Ron Abramovich, Water Supply Specialist
• USDA NRCS Snow Survey, Boise Idaho • [email protected]
Bear ProblemsWhat Is Happening?????
Van Wyck, Weiser Basin
MET Tower or Playground Equipment
Floppy Chain Link Fence Designed to
Keep the Average Bear Out!
Questions – Comments – CorrectionsAdditional and more detail information about ‘Amount Needed’ is available on the
Idaho Snow Survey Web Page at: http://www.id.nrcs.usda.gov/snow/
• Ron Abramovich, Water Supply Specialist
• USDA NRCS Snow Survey, Boise Idaho • [email protected]