Ground Water Assessment Program—GWAP

The Ground Water Assessment Program was established by the Montana Legislature (85-2-901 et seq.) in 1991 to improve the understanding of Montana's groundwater resources by collecting, interpreting, and disseminating essential groundwater information. This information is vital for making science-based management decisions.

There are three program components:

An interagency Steering Committee selects study areas, coordinates groundwater research among State, Federal, and local government units, and oversees Assessment Program progress.

Related Content

Aquifer Characterization
Groundwater Information Center
Web Mapping Application

GIS Data Hub

Contact Information

Program Information

John LaFave, Program Manager
(406) 496-4306 | Email

Office locations in Butte and Billings

Bureau Location Map

Long-term water-level measurements provide a fundamental measure for assessing the status and trends of groundwater storage. The Groundwater Monitoring Program systematically tracks long-term water-level and water-quality changes in Montana’s major aquifers. A network of strategically located wells across the State produces groundwater-level records that directly measure how Montana’s aquifers respond to seasonal, climatic, developmental, or land-use factors. The more than 800-well network includes some that have been regularly monitored since the 1950s. Several cooperators maintain local groundwater-level networks and share their data with MBMG. Cooperators include:

  • Confederated Salish Kootenai Tribes Water Resources Program
  • Gallatin Local Water Quality District
  • Missoula Valley Water Quality District
  • Lewis and Clark Water Quality Protection District
  • Sheridan Conservation District
  • Yellowstone Controlled Groundwater Area

Map to billings office

The Characterization Program maps and assesses aquifers within specific areas as prioritized by the Ground Water Assessment Steering Committee.

To date, more than 8,000 wells have been visited and about 3,000 groundwater samples have been collected. These data have been used to compile 64 maps and reports that describe aquifer productivity, groundwater-flow systems, and groundwater quality.

The Ground Water Information Center (GWIC) is Montana's groundwater information repository.

The website ( provides online access to water-well logs, hydrographs, maps of groundwater-flow systems, and water-quality reports describing groundwater conditions across the State, as well as a variety of field, chemical, and physical data.

GWIC by the Numbers

Map to billings office

  • More than 31,000 registered users
  • About 43,800 queries each month
  • Information on 251,700 wells and boreholes
  • Scanned images for 230,210 well log documents
  • Results from 87,041 water-quality analyses for 18,051 sites
  • 26.4 million water-level measurements


Drilling monitoring wells.

Drone work in the Paradise Valley.

Groundwater sampling in the Shields Valley.

Groundwater survey

Measuring a domestic well near Eureka, Montana.

Measuring groundwater levels near Ennis, Montana.