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

2008 April 1 NRCS Predicted Flows 2008 Observed April-July Flows

Low Elevation SNOTEL Sites Near Record High

But Not Higher Elevation SNOTEL Sites

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%

Finally --- Normal Snow Accumulation and Melt

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 % of average April 1 snowpack near average Spring precipitation 71-84%

103%

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” 4 th lowest in 26 years

2008 water year precipitation 79-86% of average April 1 snowpack % 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

And did not increase runoff coefficients due to fires

Looking North from Galena Summit on June 14, 2008 Typical SNOTEL sites are between feet….

Big Lost: What Happened?

2008 water year precipitation near average April 1 snowpack % Apr-Jun precipitation near average, cool temperatures kept snow in higher elevations longer.

NRCS Daily Water Supply Forecast was Right On in 2008

Unlike in 2007 when normal precipitation changed to below normal precipitation after Jan 15

Last year, we said we needed an April 1 snowpack > 106% to provide flow > 88% snow was 105% producing 103% of average runoff.

2008 water year precipitation near average April 1 snowpack % of average, but runoff % Apr-Jun precipitation 80%of average

Oakley Streamflow Forecast had Similar Relationship

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 – Corrections Additional and more detail information about ‘Amount Needed’ is available on the Idaho Snow Survey Web Page at: Ron Abramovich, Water Supply Specialist USDA NRCS Snow Survey, Boise Idaho

Bear Problems What Is Happening????? Van Wyck, Weiser Basin MET Tower or Playground Equipment Floppy Chain Link Fence Designed to Keep the Average Bear Out!

Banner Summit 2006 Central Idaho Two Ocean Divide 2006 Yellowstone National Park

New Install Hidden Lake SNOTEL about 10 miles from Canada

Replacing Gunsight Pass Pillow Oct with Chain Link Bear Resistant Cover

Edge of pulled up pillow had several teeth punctures….....

Questions – Comments – Corrections Additional and more detail information about ‘Amount Needed’ is available on the Idaho Snow Survey Web Page at: Ron Abramovich, Water Supply Specialist USDA NRCS Snow Survey, Boise Idaho