SWC Methodology - TWG

February 11, 2015

Settlement Document Subject to I.R.E. 408

Agenda

http://idwr.idaho.gov/News/WaterCalls/Surface%20Coalition%20Call/default.htm#CM-DC-2010-001

Item Time

1 1:30 - 2:00 Introduction and Overview of assignments. (Cresto) Natural flow predictor models Cropping Patterns RISD predictor tools Irrigated Acres Supplemental groundwater acres

2 2:00 - 2:45 Natural flow predictor models (Cresto)/ (Brockway)

3 2:45 – 3:00 Break

4 3:00 – 3:45 Cropping patterns (Anders)

5 3:45 – 4:30 RISD predictor tools (Anders)

6 4:30 – 4:45 Irrigated acres (Anders)

7 4:45 – 5:00 Schedule next meeting and identify topics for discussion (Cresto)

Natural Flow Predictor Models

Current April Natural Flow ModelsSWC

MemberEquation

(less one standard error)R2

A&B y = 0.0092x - 19.747 0.887

AFRD2 y = 0.0742x - 141.14 0.8317

BID y = 0.0344x - 2.5853 0.7964

Milner y = 0.0102x - 19.412 0.9243

MID y = 0.0484x + 2.7178 0.7896

NSCC y = 0.1562x - 53.005 0.8952

TFCC y = 0.0658x + 626.37 0.5416

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.

Variable Name Description UnitsHeiseAprtoJulKAF USBR Hydromet Heise Natural Flow April - July KAFMarWell1 USGS Well: WL-9S 25E 03CAC1 March depth to water FeetMarWell2 USGS Well: WL-2N 37E 02ABA1 March depth to water FeetMarWell3 USGS Well: WL-3N 37E 12BDB1 March depth to water FeetMarWell4 USGS Well: WL-8S 24E 31DAC1 March depth to water FeetMarWell5 USGS Well: WL-8S 24E 31DAC1 March depth to water FeetRupNovtoMar Rupert Agrimet Total Precipitation November - March InchesTYHEE USGS 13075910 PORTNEUF RIVER NR TYHEE ID Total Flow November - March AFLastYearNF7to9 TFCC Natural flow diversions July - September, lagged by 1 year AF

SpringCreek11to3USGS 13075983 SPRING CREEK AT SHEEPSKIN RD NR FORT HALL ID Total Flow November - March AF

SpringCr3 USGS 13075983 SPRING CREEK AT SHEEPSKIN RD NR FORT HALL ID Total Flow March AF

Devils11to3USGS 13089500 DEVILS WASHBOWL SPRING NR KIMBERLY 10S 18E 04AAD1S Total Flow November - March AF

Devils3USGS 13089500 DEVILS WASHBOWL SPRING NR KIMBERLY 10S 18E 04AAD1S total Flow March AF

Box11to3 USGS 13095500 BOX CANYON SPRINGS NR WENDELL ID Total Flow November - March AFBox3 USGS 13095500 BOX CANYON SPRINGS NR WENDELL ID Total Flow March AFBriggs11to3 USGS 13095175 BRIGGS SPRING AT HEAD NEAR BUHL ID Total Flow November - March AFBriggs3 USGS 13095175 BRIGGS SPRING AT HEAD NEAR BUHL ID Total Flow March AFTwoOceans71 NRCS Two Oceans Plateau (837) Snow Water Equivalent on July 1 InchesHEIAprtoJune USBR Hydromet Heise Natural Flow April - June KAF

SpringJantoMayUSGS 13075983 SPRING CREEK AT SHEEPSKIN RD NR FORT HALL ID Total Flow January - May KAF

NA NRCS Spring Creek Divide (779) Snow Water Equivalent on July 1 InchesNA NRCS Togwotee Pass (822) Snow Water Equivalent on July 1 InchesNA NRCS Phillips Bench (689) Snow Water Equivalent on July 1 Inches2OcTow Sum of Two Oceans Plateau and Togwotee Pass Snow Water Equivalent on July 1 Inches

Variables Tested in MLR Models.Variables in Bold were the ones chosen for use in models.SummaryVariablesTested.xlsx

New TFCC April Natural Flow Predictor

TFCC= 62.01 (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 R2 p SE DOF F-statistic0.8664 <0.001 38,010 21 75.6

Changes to Mid-Season Prediction•Mid-season adjustment to include upward adjustment of mitigation obligation if the update shows increased shortfall.

•The current methodology requires a mid-season update. However, the past mid-season updates occurred too late in the season.

Review of Current Methodology

• Updates occurred in late August and only in those years when there was a predicted shortfall in April.

Forecasted Supply = Preliminary Storage Allocation + YTD Natural Flow Diversions + Forecast Natural Flow Diversions for remainder of the season

• Forecast Natural Flow Diversions for remainder of the seasono A&B, AFRD2, MID, Milner, and MID typically have little to no natural flow diversions

in late August, September, and October. o NSCC and TFCC forecasted natural flow diversions were based reach gains from

analogous years

New Mid-Season Predictors• July 1 make predications with the idea of issuing an order around July 15.

• This is typically after the day of allocation, especially in dry years.

• Switch from analogous years to regressions models.

July 1 MLR Predictor ModelsSWC

MemberPredictor Model

Natural Flow Diversions (July – October)Adjusted

R2SE F-Statistic

BID BID = 19.86(Heise) + 1018(SpringCreek) + 1719(TwoOceans) - 113,300 0.8672 12,810 51.06

MID MID = 28.35(Heise) + 1577(SpringCreek) + 2434(TwoOceans) – 172,260

0.8808 17,490 57.63

NSCC NSCC= 93.26 (Heise) + 2708.5(SpringCreek) + 4609 (TwoOceans) – 346,520

0.9003 39,820 70.22

TFCC TFCC = 37.61 (Heise) + 2629(SpringCreek) + 3616(TwoOceans) + 137,100

0.8304 31,240 38.54

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 1 Snow Water Equivalent (in) on July 1.

July 1 Linear Predictor ModelsSWC

MemberPredictor Model

Natural Flow Diversions (July – October)R2 SE

A&B A&B = 269.28(TwoOceans) - 84.135 0.9497 509

AFRD2 AFRD2 = 1972.9(TwoOceans) - 59.48 0.9126 5,015

Milner Milner =685.63(TwoOceans) +12.797 0.8998 1,880

Where:TwoOceans is the July 1 Snow Water Equivalent (in) on July 1.

* 1997 was not included in regresssion analysis.