This webpage is an annual summary of the Methodology findings and required actions for the current irrigation year regarding the Surface Water Coalition Delivery Call.
To review and download pdf copies of the complete list of legal filings in the SWC Delivery Call (2010 – present), visit the Docket No. CM-DC-2010-001 legal webpage.
In 2005, a group of canal companies and irrigation districts that diverted and delivered water from the Snake River to approximately 550,000 acres of farmland in the Eastern Snake Plain area formed the Surface Water Coalition (SWC). Once formed, the SWC filed a delivery call with the Idaho Department of Water Resources (IDWR or “Department”) against junior ground water users claiming that junior ground water pumping was depleting the Eastern Snake Plain Aquifer (ESPA) and the hydrologically connected Snake River. The Idaho Ground Water Appropriators (IGWA) and member ground water districts formed in response to the SWC delivery call to respond on behalf of junior ground water users who were collectively irrigating almost 1,000,000 acres of farmland. Through the delivery call proceeding, it was determined that depending on surface water supply, ESPA, and crop need conditions, the depletion effects from pumping the ESPA materially injure the SWC.
The Department implemented a court-approved “Methodology” in 2010 to evaluate the water supply and crop need conditions each year to determine if there may be injury to senior surface water rights in the given irrigation year, and what the magnitude of the injury may be. The Methodology has been implemented since 2010, and during that time, it has undergone six revisions, most recently in 2023. When the Methodology determines injury, junior ground water users found to be causing the injury must mitigate their injury under the authority of a State-approved mitigation plan or be curtailed.
Current Methodology
July 19, 2023 | Sixth Final Order Regarding Methodology for Determining Material Injury to Reasonable In-season Demand and Reasonable Carryover
Surface Water Coalition and Idaho Ground Water Appropriators, Inc.:
Groundwater and Eastern Snake Plain Aquifer Information:
Senate Bill 1341
The 2024 Legislature passed Senate Bill 1341, expanding the ESPA ACGWS. The ESPA ACGWS is the administrative boundary used by the Department to administer water rights regarding the SWC Delivery Call. Senate Bill 1341 modifies the ACGWS to reflect the ESPAM boundary, version 2.2. When the new boundary goes into affect on July 1, 2024, approximately 1,400 new ground water rights will be brought into the delivery call proceeding. The Department sent notice to the holders of affected water rights in May and is currently considering the process to bring the new water rights into administration.
Click on the links below for information and resources regarding the SWC Delivery Call and the 2024 Curtailment Order:
Methodology and Curtailment Orders
- Order Approving 2024 Stipulation as Compliance with Approved Mitigation Plan – June 20, 2024
- Second Order Amending Curtailment List – June 20, 2024
- Order Amending Curtailment List – June 6, 2024
- Final Order Curtailing Ground Water Rights Junior to March 31, 1954 —May 30, 2024
IDWR Press Releases and FAQs
- FAQs: Overview and Background on the Director’s May 30, 2024 Curtailment Order – June 7, 2024
- SWC, ESPA ground water districts reach settlement agreement, avoid curtailment in 2024 – June 20, 2024
- Director Weaver pauses water right curtailment compliance inspections – June 13, 2024
- Two Magic Valley-area ground water districts move to comply with approved mitigation plans and avoid curtailment – June 6, 2024
- IDWR Director issues curtailment order for six ESPA groundwater districts; order affects groundwater users whose water rights are junior to March 31, 1954 – May 30, 2024
- IDWR Director finds ESPA ground water districts’ mitigation plans deficient in addressing water shortfall; ground water users have a week to resolve issue – May 10, 2024
- IDWR finds 74,000 acre-foot shortfall in April 2024 Methodology Order; Junior groundwater users could face potential curtailment – April 19, 2024
- IDWR Director: Updated July methodology order finds no injury to senior or junior water users in 2023 irrigation season – July 20, 2023
- IDWR updates Methodology for predicting Snake River shortfalls – April 25, 2023
2025 Irrigation Season
Methodology and Related Orders
April 16, 2025 | Final Order Regarding April 2025 Forecast Supply (Methodology Steps 1–3)
- The Director predicts an April IDS of 63,000 acre-feet.
- On or before May 1, 2025, ground water users holding consumptive water rights bearing priority dates junior to August 28, 1955, within the ESPA ACGWS shall establish, to the satisfaction of the Director, that they can mitigate for their proportionate share of the predicted April IDS of 63,000 acre-feet in accordance with an approved mitigation plan.
- If a junior ground water user cannot establish, to the satisfaction of the Director, that they can mitigate for their proportionate share of the predicted April IDS in accordance with an approved mitigation plan, the Director will issue an order curtailing the junior-priority ground water user.
- Visit Docket No. CM-DC-2010-001 to download the April Background information.
IDWR Press Releases and FAQs
April 16, 2025 | IDWR finds 63,000 acre-foot shortfall of water in April 2025 Methodology Order; Director applauds farmers who are in compliance with mitigation plans
Acronyms on this Webpage
ACGWS – Area of Common Ground Water Supply
IDS – In-Season Demand Shortfall
IGWA – Idaho Ground Water Appropriators
ESPA – Eastern Snake Plain Aquifer
ESPAM – Eastern Snake Plain Aquifer Model
SWC – Surface Water Coalition
The map above illustrates the new boundaries of the ESPA ACGWS, updated as per Senate Bill 1341, of the 2024 Legislative Session. The updated boundary went into effect on July 1, 2024 and is defined under Idaho Code § 42-233c.
Click here for a pdf version of the updated ESPA ACGWS Map.
