1. Return Flow Discussion ESHMC Meeting 6 March 2008 Presented by Stacey Taylor 1

2. Overview Bryce Contor’s slides Historical data analysis: – IESW007 (Big and Little Wood Rivers) – IESW054 (Richfield) Ongoing Snake River return data (groups) General conclusions 2

3. 3 Current Calculation Method Diversions Returns Returns = b 1 * Diversions (one equation for each entity)

4. 4 Alternate Methods Diversions Returns Returns = b o (one equation for each entity) Diversions Returns Returns = b o + b 1 * Diversions (one equation for each entity) Diversions Returns Returns = -b o + b 1 * Diversions) (one equation for each entity) Diversions Returns Returns = logarithmic function (one equation for each entity) Returns = exponential function (one equation for each entity) OR Alternate Method (1)Alternate Method (2) Alternate Method (3)Alternate Methods (4) and (5)

5. Raster Graphics Created several raster graphics to represent returns and diversions for IESW007 and IESW054 Different colors represent different diversions/returns. 5

6. Example Raster (1) 6 Water Year Month Oct.Sept. 0 5 10 15 20 Diversion 1,000 ac-ft 1928 2004

7. Example Raster (2) 7 Water Year Month Oct.Sept. 0 5 10 15 20 Diversion 1,000 ac-ft 1928 2004

8. Example Raster (3) 8 Water Year Month Oct.Sept. 0 5 10 15 20 Diversion 1,000 ac-ft 1928 2004

9. IESW007 Total Diversions (Big and Little Wood Rivers) 9 Water Year 1928 1940 1950 1960 1970 1980 1990 2004 Month 101112123456789 Diversion (1,000 ac-ft) 0 10 20 30 40 50 60 70 80 90

10. Return (1,000 ac-ft) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.6 Water Year 1928 1940 1950 1960 1970 1980 1990 2004 Month 101112123456789 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.7 IESW007 Total Returns (Big and Little Wood Rivers) 10

11. IESW054 Total Diversions (Richfield) 11 Diversion (1,000 ac-ft) Water Year 1928 1940 1950 1960 1970 1980 1990 2004 Month 101112123456 7 8 9 0 10 20 30

12. IESW054 Total Returns (Richfield) 12 Return (1,000 ac-ft) 0 5 20 Water Year 1928 1940 1950 1960 1970 1980 1990 2004 Month 101112123456789 10

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16. Cumulative Return vs. Cumulative Diversion IESW054 (Richfield) 16

17. What Caused the Change? Change in slope of cumulative plots – Possibly related to conversion to sprinklers – Calibration data shows percentage these increases: IESW007 – May 1980 to May 2002 sprinkler % increased from 14.7% to 28.0% (13% increase) IESW054 – May 1980 to May 2002 sprinkler % increased from 31.9% to 59.7% (28% increase) Aerial photography covering the area encompassed by both entities has been requested for 1969 and 1977 17

18. Regression Analysis A regression analysis was performed on each set of data (1928-1950, 1951-1970, etc) P-values were found for each intercept and slope (95% confidence interval) Given shared ranges between each set of data, a general equation may describe both entities (IESW007 and IESW054) 18

19. IESW007 Intercepts and Slopes (Based on 95% CI) 19 Shared intercept range: -3.76 to -3.67Shared slope range: 0.0173 to 0.0235 y = 0.02x – 3.70

20. IESW054 Intercepts and Slopes (Based on 95% CI) 20 No shared slope range between all sets; 1981-2004 slope is negative Shared slope range: 0.170 to 0.177 y = 0.17x - ???

21. Ongoing Snake River Return Data Group data for 2002-2006 were compared to IESW007 and IESW054 Plotted returns vs. diversions Plotted returns vs. normalized diversion (Normalized diversion = diversion/max diversion of single entity) Plotted normalized returns vs. normalized diversions 21

22. Returns vs. Diversions for Separate Entities 22

23. Returns vs. Normalized Diversion 23

24. Conclusions Current technique of assuming straight line plot with zero intercept may still be best (Returns = b 1 *Diversions) Slope (b 1 ) based on historical data OR lag factors (depends on which is available) Slope may be better estimated with inclusion of latest data 24

25. Discussion 25