Big Sky, Gallatin and Madison Counties

Background

Big Sky is a recreational and residential ski resort located about 40 miles south of Bozeman. The area is divided into four major resorts that work cooperatively on growth and development plans. The Big Sky, Spanish Peaks, and Yellowstone Club resorts occupy portions of the West Gallatin River drainage, which discharges to the Gallatin River; Moonlight Basin lies to the west, at the head of the Jack Creek drainage, which discharges west to the Madison River. Bedrock aquifers are structurally complex and are overlain by unconsolidated alluvial and glacial sands and gravels. As groundwater resources are developed, concerns are related to water availability, water-rights, water-quality, and uncertainties in aquifer capacities and their ability to sustain current use and future growth.

Purpose

The purpose of the project is to provide the hydrogeologic framework for the bedrock aquifers in the Big Sky area in order for local and State entities to evaluate the effects of future water development. The effects of additional groundwater withdrawals from the Meadow Village aquifer on groundwater and the Gallatin River were evaluated using a numerical groundwater flow model.

Project Scope

Groundwater and surface-water data were collected from 2013 through 2016. Water levels were monitored monthly in 67 private and public water supply wells. Discharge and water-quality parameters were measured at 28 surface-water locations, with a special focus on the West Fork Gallatin River near the Meadow Village Golf Course. Fifteen groundwater monitoring wells were drilled in the Meadow Village sand and gravel aquifer to better define the aquifer geometry. Water samples from 40 wells and 9 surface-water sites were analyzed for water chemistry and isotopes.

A numerical groundwater flow model for the Meadow Village aquifer was developed to evaluate the effects of new water development on groundwater and surface water.

Results

Most aquifers are small and localized due to geologic heterogeneity – this limits the amount of water available to a given area. The three most productive aquifers at Big Sky are the sand and gravel aquifer at Meadow Village, glacial and alluvial fan deposits at Mountain Village, and fractured dacite around the core of the Lone Mountain Intrusion. Groundwater levels decline quickly during seasonally intensive pumping from high visitation usage, summertime landscape watering, and snowmaking early in the ski season. However, groundwater levels recover at the end of high-use periods and met the current demands for water under the pumping and climate conditions of 2014-2016. While groundwater resources are capable of supporting current water use, additional stresses and demands on the aquifers might not be sustainable.

Project Reports

• Hydrogeology and groundwater availability at Big Sky, Montana (Rose, J., and Waren, K., 2022)
  View in Catalog

Download report (32 MB)
Download plate 1 (185 KB)


• Groundwater model of the Meadow Village aquifer at Big Sky, Montana (Waren, K., Rose, J., and Breitmeyer, R., 2021)
  View in Catalog

Download report (3.5 MB)
Download Model Files (Daily Base GMS) (10 MB)
Download Model Files (Daily Base Text) (9 MB)
Download Model Files (Monthly Base GWVistas) (33 MB)
Download Model Files (Monthly Base Native) (32 MB)
Download Model Files (Monthly Base GMS) (9.5 MB)
Download Model Files (SS GMS) (27 MB)
Download Model Files (SS GWVistas) (1.6 MB)
Download Model Files (SS Native) (0.8 MB)

Presentations

• Groundwater models for the Meadow Village alluvial aquifer, Big Sky, Gallatin County, Montana
  
• Big Sky Groundwater Investigation Update to the Big Sky Water and Sewer District Board, Big Sky, MT, May 24, 2016
  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: 11/17/2022 12:53:24 PM