SWC Methodology - TWG February 19, 2015 Settlement Document Subject to I.R.E. 408

Update on Natural Flow Predictor Models

April 1 Models Considering using other forecasts Predictor models for all SWC members Relationship between Box Canyon and Blackfoot to Milner reach gains.

NRCSUSACOE/USBRAveraged NRCS/USACOE&USBR %12%18% 20011%13%7% %12%13% 20037%3%5% %-13%-16% % %24% 20071%0%1% %-12%-11% %-26%-31% %-20%-17% %12%5% 20125%16%11% %14%19% 20142%3% Average2%3% Standard Deviation18%15%16%

New TFCC April Natural Flow Predictor TFCC= (Heise) +12,980(Box) – 609,600 Where: TFCC = TFCC natural flow supply from April to October; Hei = Heise natural flow forecast from April – July in (KAF); Box = Box Canyon total flow from November through March (KAF). Adjusted R 2 pSEDOFF-statistic < ,

Current April Natural Flow Models SWC Member Equation (less one standard error) R2R2 A&By = x AFRD2y = x BIDy = x Milnery = x MIDy = x NSCCy = x TFCCy = x Where: y = Natural flow April – October for the SWC Member (AF); x = Heise Natural Flow (April 1 – July 31). USBR/ACOE Heise forecast is used in April. *To error on the side of the SWC, natural flow predictions are one standard error below regression line.

April 1 Predictor Models for other SWC Members Used the same variables that were used for TFCC model: – Heise – Box Canyon Found no model improvement for: – A&B – AFRD2 ? – Milner – All have late priority NF rights

SWC Member Water Right Priorities A&B1939 AFRD21921 BID1903, 1908, 1939 Milner1916, 1939, 1939 MID1903, 1908, 1939 NSCC1900, 1905, 1908, 1915, 1920 TFCC1900, 1915, 1939

Multilinear Regression Model : AFRD24to10 = HeiseAprtoJulKAF + Box11to3) Residuals: Min 1Q Median 3Q Max Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) * HeiseAprtoJulKAF e-10*** Box11to Signif. codes: 0 ‘***’ ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: on 21 degrees of freedom Multiple R-squared: ,Adjusted R-squared: F-statistic: on 2 and 21 DF, p-value: 1.233e-09 AFRD2 April 1 Models Linear Regression Model: AFRD24to10 = HeiseAprtoJulKAF Residuals: Min 1Q Median 3Q Max Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) e e *** HeiseAprtoJulKAF 7.418e e e-10 *** --- Signif. codes: 0 ‘***’ ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: on 22 degrees of freedom Multiple R-squared: ,Adjusted R-squared: F-statistic: on 1 and 22 DF, p-value: 5.604e-10

April 1 MLR Predictor Models SWC Member Predictor Model Natural Flow Diversions (April – October) Adjusted R 2 SEF-Statistic BIDBID = 33.64(Heise) (Box) – 240, , MIDMID = 47.12(Heise) (Box) – 401, , NSCCNSCC = (Heise) (Box) – 677, , TFCCTFCC= (Heise) +12,980(Box) – 609, , Where: Heise is the total Heise natural flow from April – June in (KAF); Box = Box Canyon total flow from November through March (KAF).

Current April Natural Flow Models SWC Member Equation (less one standard error) R2R2 A&By = x AFRD2y = x BIDy = x Milnery = x MIDy = x NSCCy = x TFCCy = x Where: y = Natural flow April – October for the SWC Member (AF); x = Heise Natural Flow (April 1 – July 31). USBR/ACOE Heise forecast is used in April. *To error on the side of the SWC, natural flow predictions are one standard error below regression line.

Box Canyon Discussion

July 1 Models Two Oceans Plateau SWE – Consider using an earlier date to remove years with zeros Concerns over using Spring Creek data. – Consider using only metered data – Investigate using other indicators Tyhee (missing data 1995 – 2001) Wells Predict total natural flow in the Blackfoot to Milner reach then allocate by priority

Two Oceans Plateau Looked at June 1 and June 15. June 15 had better results than June 1. June 15 data set has 4 years with zero SWE July 1 data set has 13 years with zero SWE

July 1 MLR Predictor Models SWC Member Adjusted R 2 SEF-Statistic BIDOld New ,810 14, MIDOld New ,490 20, NSCC New ,820 47, TFCC New ,240 29, Where: Heise is the total Heise natural flow from April – June in (KAF); SpringCreek is Spring Creek total flow from January - May (KAF); TwoOceans is the July 15 Snow Water Equivalent (in).

Spring Creek Alternatives