Eureka, Lincoln County

Background

Development in the Tobacco Valley is increasing the demand for water. Balancing water management, development, and conservation requires a thorough understanding of how groundwater aquifers and surface waters interact. These processes are complex in the Tobacco Valley due to the highly variable nature of the glacially derived valley fill sediments. In particular, a more detailed understanding is needed of where new groundwater pumping would be likely to deplete stream flows in the Tobacco River.

Purpose

Understand how groundwater development will affect the availability of groundwater and surface water in the Tobacco Valley.

Project Scope

The project scope includes developing the hydrogeologic framework, water budget, and constructing a numerical groundwater model to simulate hydrologic conditions and predict the effects of groundwater pumping on the hydrogeologic system. Data collection included:

1)monitoring groundwater levels in a network of wells;

2)measuring stream flow to determine where streams gain water from or lose water to the aquifer;

3) installing wells to refine models of the distribution of aquifers and aquitards, to allow monitoring in areas with no available wells, and to evaluate hydrologic connections between aquifers and surface water; and

4) conducting aquifer tests to refine estimates of aquifer properties.

Project Status

Monitoring activities have been completed. Modeling and data analysis are underway.

Project Reports

• Three aquifer tests in the Tobacco Valley, near Eureka, Montana (Bobst, A., 2024)
  View Report
• Eureka Fact Sheet: June 2023
  View Report

Project Personnel

Andy Bobst	Project Lead, Research Hydrogeologist
Ali Gebril	Associate Research Hydrogeologist, Groundwater Modeler
Tyler Storey	Professional Scientist Research Hydrogeologist

Presentations

• An Update on the Eureka Groundwater Investigation. Presentation at public meeting, MT, November 21, 2024, Eureka, MT.
  
• An Update on the Eureka Groundwater Investigation. Presentation at public meeting, MT, November 21, 2024, Eureka, MT.
  View Presentation

Link to Project Data

Data collected for this project can be accessed through the Ground Water Information Center (GWIC) database:

Download project data from GWIC