East Flathead Valley, Flathead County

Background

Ongoing development in the Flathead Valley is increasing the demand for water. Balancing water management, development, and conservation requires a thorough understanding of how the shallow and deep aquifers and the surface waters interact. In particular, evaluating the continuity and permeability of the confining layer will help determine the extent to which the deep and shallow aquifers are connected.

Purpose

This study will provide a detailed understanding of the interconnection between groundwater and surface waters on the east side of Flathead Valley and will evaluate groundwater availability as the demand increases with residential and commercial development.

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 pumping on the hydrogeologic system.

Project Status

Groundwater and surface-water monitoring is complete, including aquifer tests. Modeling and aquifer test reports have been published (see below). Final report writing and editing are underway.

Results

This study shows that the confining layer is not continuous throughout the East Flathead area, and groundwater withdrawals from both the shallow and deep aquifers will eventually cause stream depletion. The magnitude of this stream depletion on the Flathead River is likely to be too small to measure. Modeling also indicates that natural variations in groundwater recharge at the Swan Range front is likely to cause more noticeable variations in groundwater levels and groundwater discharge to surface waters than groundwater pumping.

Project Reports

• A groundwater flow model for the East Flathead Valley, Flathead County, Montana (Berglund, J., Bobst, A., and Gebril, A., 2024)
  View Report
• Analyses of three constant-rate aquifer tests, East Flathead Valley, northwest Montana (Myse, T., Bobst, A., and Rose, J., 2023)
  View Report

Project Personnel

Andy Bobst	Senior Hydrogeologist, Project Manager
Ali Gebril	Associate Research Hydrogeologist

Presentations

• Developing a Groundwater Flow Model for the East Flathead Valley. Presentation to the Montana American Water Resources Association (AWRA), October 9-11, 2024, Whitefish, Montana.
  View Presentation
• An Overview of the East Flathead Groundwater Investigation. Presented at public meeting, October 8, 2024, Kalispell, 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

Content last updated: 5/11/2022 10:50:59 AM