Somach Simmons and Dunn, Attorneys at Law Somach Simmons & Dunn | Attorneys at Law

Subscribe to our eAlerts

Please complete the form below to subscribe and recieve our monthly eAlerts via email.

May 21, 2024  |  Written by Maximilian C. Bricker

IDWR’s Development of a Ground Water Management Plan for the Eastern Snake Plain Aquifer

A prior alert provided an overview of various administrative matters before the Idaho Department of Water Resources (IDWR) that share a common theme: increasing the regulation of pumping by junior ground water users along the Eastern Snake Plain Aquifer (ESPA), under its conjunctive management authority, to protect the rights of senior surface water users. This alert focuses on one of those ongoing IDWR matters: the development of a Ground Water Management Plan (GWMP) for the ESPA Ground Water Management Area (ESPA-GWMA).


In November 2016, the IDWR Director issued an Order Designating the Eastern Snake Plain Aquifer GWMA (Designation Order), wherein he concluded that “the ground water basin encompassing the ESPA may be approaching a condition of not having sufficient ground water to provide a reasonably safe supply for irrigation and other uses occurring within the basin at current rates of withdrawal.” Designation Order at 19. Below is a graph depicting changes in aquifer storage volumes and discharges from a spring near Hagerman, Idaho—from 1912 to present:



The Designation Order further provides that a GWMP “would provide the framework for managing ground water [within the ESPA-GWMA] to ensure a reasonably safe supply [the statutory standard for GWMAs] of ground water for irrigation of cultivated lands or other uses in the basin.” Id. at 23.

In June 2015, just over a year before the Designation Order, the Surface Water Coalition (SWC)—a group of canal companies and districts holding senior surface water rights—and Idaho Ground Water Appropriators, Inc. (IGWA)—a group of ground water districts with patrons holding junior ground water rights—entered into an SWC-IGWA Settlement Agreement that was intended to create certainty with IDWR’s conjunctive management of surface and ground water rights across the ESPA-GWMA, and avoid significant curtailment of wells.

The geographic relationship between IGWA and SWC members. Source:

In exchange for protection from curtailment, IGWA agreed to reduce pumping and/or recharge 240,000 acre-feet annually; deliver 50,000 acre-feet of storage water to SWC annually; and restore aquifer levels to “a level equal to the average of the aquifer levels from 1991-2001” by 2026. The Designation Order referenced the SWC-IGWA Settlement Agreement by stating: “the Settlement Agreement will be a key part of any future [GWMP] and it will be appropriate to incorporate all or part of the settlement into an ESPA [GWMP].” Designation Order at 24.

In 2018, several municipalities that pump ground water from the ESPA entered into a SWC-Cities Settlement Agreement with both SWC and IGWA. The Cities agreed, in exchange for protection from curtailment, that their mitigation obligations to SWC are to recharge 7,650 acre-feet on an annual average basis. In addition, the SWC-Cities Settlement Agreement includes the following terms: (1) IGWA’s and the Cities’ respective mitigation obligations “will be submitted to IDWR for approval as a [GWMP]” for each group; (2) all parties will “support a [GWMP] that incorporates such obligations”; and (3) if, however, the GWMP imposes obligations on the Cities that are “materially greater or more burdensome” than their existing obligations, the Cities reserved the right to challenge the GWMP.

The Latest on IDWR’s Development of a GWMP

In summer 2023, IDWR assembled an Advisory Committee, composed of representatives from surface water users, ground water irrigators, and municipalities, to develop a GWMP. The Committee met monthly from September 2023 to February 2024, where it attempted to tackle difficult threshold questions, such as:

  • What are the GWMP’s goals?
  • What actions must be taken “to ensure a reasonably safe supply” of ground water for existing uses—stabilizing the aquifer or restoring the aquifer?
  • Will any pumping reductions be borne equally by all pumpers, or will it vary based on type of use (irrigation v. municipal) or priority (senior pumpers receiving a higher allocation than junior pumpers)?

Each represented group presented their own proposed frameworks for the GWMP to the Advisory Committee during that time—surface water user interests advocated for aquifer restoration, ground water irrigator interests advocated for aquifer stabilization, and municipal interests emphasized that the GWMP must not increase their existing mitigation obligations. IDWR staff attempted to create one combined framework. However, because the groups could not reach common ground on fundamental components of a GWMP, the Advisory Committee splintered and did not meet in March or April, with IDWR staff instead meeting with the groups separately.

Meanwhile, certain ground water irrigation interests have begun developing their own proposed GWMP that provides for: (1) aquifer stabilization; and (2) pumping reductions by municipalities. Both terms are controversial and inconsistent with the language in IGWA’s and the Cities’ settlements. Thus, additional questions have arisen, such as:

  • Must there only be one GWMP, or can there be multiple GWMPs for the ESPA-GWMA?
  • Must the GWMP(s) incorporate the Cities’ and IGWA’s existing mitigation obligations verbatim, per the SWC-Cities Settlement Agreement, and if not, what happens?

IDWR has not announced the next Advisory Committee meeting. The Director has said publicly he expects to see a proposed GWMP on his desk, for his approval, by the end of 2024. Whether that expectation is attainable—and whether a GWMP can be adopted and implemented without litigation—remains to be seen.

For more information or with questions, please contact:

Somach Simmons & Dunn represents the City of Pocatello and American Falls-Aberdeen Ground Water District in legal matters including, but not limited to, those described herein. This alert reflects the observations of the authors and is not intended to limit or otherwise describe the views of our clients.

Read more news and alerts »