Idaho Groundwater Appropriators Hydrogeological Services

Across the United States, Idaho is among the most reliant on groundwater–accounting for 6% of the overall national utilization of groundwater resources. Extracting tens of millions of gallons of groundwater every day, the natural resource supports all sectors of the state’s water use. However, sustained pumping of Idaho’s aquifers has prompted concerns regarding future groundwater availability to meet the state’s domestic, industrial, agricultural, and environmental needs. As groundwater is recognized as a valuable but finite resource in the State of Idaho, it is highly sought after and can prompt conflict and uncertainty regarding its ownership and allocation. The distinction of water rights is a multifaceted process, intricately determined through a number of scientific methodologies and legal negotiations, however crucial for responsible and sustainable consumption of groundwater.

Intelligent conjunctive use of surface and groundwater supplies seeks to beneficially utilize available supplies to meet the water demands across all sectors, within the constraints of Idaho’s implementation of the Prior Appropriation water rights doctrine. In the late 1990s, the Idaho Department of Water Resources (IDWR) developed a groundwater flow model of the ESRP, and that model has been applied for water rights administration since then. While it was developed by the IDWR, the agency convened an Eastern Snake Hydrologic Modeling Committee (ESHMC) to review and comment on the model, with representation from nearly all of the key water users in the region. The model has been subject to several updates since then, and the ESHMC involvement has been maintained via regular meetings (annually at a minimum).

The Idaho Groundwater Appropriators (IGWA) represent many of the users that rely strictly on their groundwater rights. Lynker has been providing expert support to IGWA in the evaluation of conjunctive administration of groundwater rights on the Eastern Snake Plain for more than a decade. As detailed below, this includes analysis and modeling of aquifer management scenarios, mitigation plans, new water right adjudications, transfer of water rights, and water rights change cases.

Lynker provides to IGWA water rights support in the form of expert reports, expert testimony and technical support in settlement negotiations on a number of legal issues where IGWA is a party. Litigation in support of water rights for IGWA proceedings includes basin-scale water management modeling, historical consumptive use analysis, evaluation of surface/groundwater interactions, evaluation of managed aquifer recharge projects, conjunctive use administration, stream depletion analysis and development of protective terms and conditions for decrees and in settlement negotiations.

Lynker has supported IGWA in several water delivery call proceedings brought by senior water right holders on the Snake River, including in:

• The Swan Falls Settlement Agreement concerning the development of monitoring and measurement protocols for minimum stream flows designated under the agreement terms, and.
• The Surface Water Coalition Settlement Agreement with groundwater modeling of management scenarios, managed recharge efforts, annual conservation activities, and reach gains analysis.

Finally, Lynker also provides expert support in the evaluation and development of the Eastern Snake Plain Aquifer Model (ESPAM), representing IGWA on the IDWR ESHMC.