Official Government Website

Surface Water Coalition Delivery Call

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

IDWR Press Releases and FAQs

2025 Irrigation Season

Methodology and Related Orders

May 16, 2025 | Final Order Curtailing Ground Water Rights Junior to August 28, 1955

  • Effective May 31, 2025, ground water users holding water rights bearing priority dates junior to August 28, 1955, within the ESPA ACGWS, and listed in Attachment A of the Curtailment Order, shall curtail/refrain from diversion and use of ground water pursuant to those water rights unless notified by the Department that the order of curtailment has been modified or rescinded as to their water rights. 
  • The Curtailment Order applies to consumptive ground water rights, including but not limited to, agricultural, commercial, industrial, and municipal uses. 
  • The Curtailment Order excludes ground water rights used for de minimis domestic purposes where such domestic use is within the limits defined in Idaho Code § 42-111, and ground water used for de minimis stock watering where such stock watering use is within the limits defined in Idaho Code § 42-1401A(11), pursuant to IDAPA 37.03.11.020.11.

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.

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