Has Idaho Bitten Off More Than It Can Chew? Climate Change Impacts in the Snake River Basin Nathan VanRheenen and Richard N. Palmer Dept. of Civil and Environmental Engineering -University of Washington- CIG Seminar - May 27, 2004

Politically Incorrect Title: Future Streamflow Scenarios and System Management in the Face of: Dwindling fish stocks Thirsty farmers Demanding energy users Effective lobbyists Government “solutions” Climate change Tragically slow decision-making processes

In the beginning … Colsim, Alan Hamlet Developed to investigate climate change impacts on Columbia River Basin water resources Fish, Power, Irrigation, M&I Very effective for Col R main stem Major Drawback Snake River Basin inadequately represented Most significant tributary 427 TAF Flow Aug. rule Our Goal (Palmer, Lettenmaier, VanRheenen, Hamlet) Develop a well-represented Snake River model of similar scale and usefulness of Colsim

Goals of Research What are the long-range impacts of climate change on the managed system? Goal: Develop a model that incorporates current and future operating rules and management strategies Simulation Model of Snake River Basin (SnakeSim) How can the potential impacts of climate change be mitigated? Goal: Develop a model that provides the “best” management strategy for SRB users Optimization Model of SRB (SnakeOpt)

Background – Snake River Basin Snake River – 1000 miles long 20 major reservoirs 14 MAF storage 17 MAF demands/water rights 700 MW hydropower capacity Brief history

Snake River Basin to Brownlee

Snake River Plain Aquifer

Political Landscape Many users Many opinions Scientific controversy Established positions Political activism

Political Landscape No More Ignoring the Obvious – Idaho Sucks Itself Dry – HCN, 2/95 “The department has handed out water rights and groundwater permits as if there’s no tomorrow." "The fish were there first, but they didn’t fill out the (water rights) forms."

Political Landscape 1995 – BOR agrees to provide 427 TAF/yr for flow augmentation Goal likely to be met 80% of years Irrigation shortages that result 72 TAF in ave years, 335 TAF in dry years 427 TAF goal unmet in last 3 yrs due to drought “Flow augmentation is a failed experiment that has been scientifically discredited and should be dropped.” - Water Coalition President, Oct 2003

Political Landscape Snake River water right moratorium ends, but permits will not be processed – DOE, 7/99 To Breach or Not to Breach – HCN, 2/00 Salmon Plan Calls for Sacrifices, Federal Remedies Contain Something for All Sides to Criticize – SSR, 7/00 Dredging Plans Stall on the Snake River – HCN, 3/03 Andrus says Dams a Problem, but Breaching is Impractical – SSR, 9/03 Calls for “Dramatically revamping river management policies”

Political Landscape Advocates file suit to help protect fish – SSR, 1/17/04 Fish Lobby: “Operation of the bureau's upper Snake projects has a profound impact on the survival of Snake River salmon, and even affects fish downstream in the Columbia.” Water Coalition Lobby: “It's an unfortunate reality that they're fixated on trying to secure Idaho water and send it downriver for a failed experiment.”

Political Landscape Snake River Basin Adjudication May 15, ID, BOR reach agreement with Nez Perce after 10 years of negotiations Agreement Tribe 50 taf water right for tribal lands, dated 1855 $23M for new sewer and water system $50M trust for land/water acquisition + $7M land 200 taf of Dworshak storage for summer flow aug  427 taf Flow Augmentation Rule nearly “guaranteed”

Snake River Models

SnakeSim VIC Hydrology Model Changes in Mean Temperature and Precipitation or Bias Corrected Output from GCMs SnakeOpt

PNW Climate Change Scenarios ~ C~ C Somewhat wetter winters and perhaps somewhat dryer summers

Snake System Flows – Jackson Lk

Snake System Flows – Milner

Snake System Flows – Boise/Payette

Snake System Flows – Dworshak R.

Snake System Flows – Clarkston

Overall Streamflow Trends - comp2020

SnakeSim Operations Model

Purpose: Measure the projected impacts of climate change on SRB water resources Considers Major surface water features Accepted management practices/rules System uses e.g., flood control, irrigation, fish, hydropower Groundwater/Surface water interactions

SnakeSim – Upper Snake Storage

SnakeSim – Middle Snake Storage

SnakeSim – Boise/Payette Storage

SnakeSim – Dworshak Storage

SnakeSim – Snake System Storage

Overall Storage Trends - comp2020

SnakeSim – Groundwater Response Recharge/discharge change as irrigation patterns change Decreases in irrigation result in decreases in recharge and discharge BOR estimates SRPA elev decreases 40 feet in next 50 years due to irrig. restrictions Impacts of mgmt likely far greater than impacts of climate change on gw

Snake River Plain Aquifer

SnakeSim – Implications Nature of flow shifts due to climate change are significant… Water quality and fish implications System operations implications Need to investigate impacts on water rights system and conjunctive uses Managed recharge as a cc mitigation strategy But, “best” mitigation techniques aren’t known

SnakeOpt Purpose: Develop a model that provides the “best” management strategy for SRB users Considers Major surface water features System uses e.g., flood control, irrigation, fish, hydropower Groundwater impacts 5 Major Irrigation Districts Economic Objective Function

SnakeOpt - Approach LP/SLP Decomposition Objective Function 5-year Model Maximize Z = Flood control benefit + Environ. benefit + Farming profit + Hydropower profit Subject to Inflows, PET, Precip, Crop values and costs, Energy demand, Groundwater

SnakeOpt - Approach LP/SLP Decomposition Objective Function 1-year Model Redefine constraints with 5-year model month 12 conditions Add value judgments to obj fn components

SnakeOpt - Approach 2 Applications 1. Long-Range Planning yrs to planning horizon Evaluate long-term optimal system operation strategies 2. Annual Planning Given 3-5 year forecast and predicted ENSO/PDO states How much water can irrigators, utilities, and fish get in the next year to ensure a sustainable future?

SnakeOpt – 1 st Cut (no hydropower) 427 TAF met

SnakeOpt - Demonstration No hydropower due to running SLP time No flood control costs/benefits Loose Flow/Storage constraints No environmental costs/benefits Min flow target constraints

Integrated SnakeSim/SnakeOpt Framework Purpose To test optimal management strategies in the simulated system and evaluate their “true” effectiveness Approach Perform rigorous sensitivity analysis in SnakeSim around optimal values to generate tradeoff curves for management

Integrated SnakeSim/SnakeOpt Framework Preliminary feedback from IDWR as to the general approach and purpose “Potentially of tremendous value” Allow first glimpses into impacts of “shifting uses” Adaptation of approach to other regional water suppliers

SRB Modeling Effort - Horizon End June Complete SnakeOpt and integrated SnakeSim/SnakeOpt model Mid June Incorporate 85-year streamflows into SnakeSim and SnakeOpt Improved ET calculation June, July Interview ID water users for value judgment data Meet with IDWR to discuss results, etc.