1. US Army Corps of Engineers BUILDING STRONG ® Corps of Engineers Omaha District Forecast Update Brian Twombly Kellie Bergman January 2010 Jay Lincoln

2. BUILDING STRONG ® Volumetric Water Supply Forecasts  Bureau of Reclamation projects  Joint-use/flood control storage needed for expected runoff volume ► Clark Canyon Dam, MT 50,000 acre-feet ► Canyon Ferry Dam, MT 795,000 acre-feet ► Tiber Dam, MT 260,000 acre-feet ► Boysen Dam, WY 145,000 acre-feet ► Yellowtail Dam, WY 240,000 acre-feet  Informational purposes only ► Glendo Dam, WY

3. BUILDING STRONG ® Multi-Variable Linear Regression  Computing April to July “natural” inflow volume to the project.  Independent predictor variables: 1.Antecedent conditions 2.The basin average snow water equivalent (SWE) 3.Spring-season precipitation

4. BUILDING STRONG ® Example of Volumetric Water Supply Forecast (Canyon Ferry Reservoir) IF = 2.023(ANTON) + 0.177(SAPR) + 0.265(PREAMJ) - 3.081 IF = The forecasted natural April through July inflow volume to Canyon Ferry in MAF. ANTON = The natural October and November antecedent runoff volume in MAF. SAPR = The average April 1 snowpack water content in inches of 9 snotel stations. PREAMJ = The average monthly precipitation in inches for 9 stations for each month of April, May, and June.

5. BUILDING STRONG ® Forecast Improves as Season Progresses and More Data becomes Available Standard ForecastError of EquationR-SquaredEstimate Jan 10.18870.6715 Feb 10.38960.5824 Mar 10.43070.5625 Apr 10.54790.5013 May 10.64150.4464 Jun 10.79770.3353 Jul 10.86100.2779

6. BUILDING STRONG ® Model Development Using ARRA Funding  Modeling is overseen by the USACE Hydrologic Engineering Center  West Consultants in San Diego, CA  Modeling three different locations: ► Chatfield Dam in Denver, CO ► Fall River near Hot Springs, SD ► James River upstream of Lamoure, ND

7. BUILDING STRONG ®

8. Fall River Basin, HEC-HMS models.

9. BUILDING STRONG ® Fall River Basin, HEC-HMS models for the Cold Brook and Cottonwood Reservoir Basins.

10. BUILDING STRONG ® James River Basin, HEC-HMS models for the Jamestown Reservoir Basin and downstream of the reservoir to Lamoure, ND.

11. BUILDING STRONG ® Chatfield Dam, HEC-HMS models for the Chatfield Basin and downstream to the Henderson Stream Gage in the South Platte River and HEC ResSim model for Chatfield Reservoir.