Madison, Jefferson, Gallatin, and Broadwater Counties have been working with the Federal Emergency Management Agency (FEMA) and Montana Department of Natural Resources and Conservation (DNRC) to produce new floodplain maps for portions of the Madison, Ruby, Jefferson, Beaverhead and South Boulder Rivers, and Mill and Indian Creeks.

See project extents here.

Updated floodplain maps will depict the latest, most accurate flood risk data, and will eventually result in updated FEMA floodplain maps. Most of the existing FEMA floodplain maps and Madison County floodprone maps are based on data from the 1980s and 1990s.

New floodplain maps from this project are not expected to be finalized for a while – draft maps may be available to start reviewing in 2020, but the study and maps will need to go through a lengthy technical and public review process before they can be finalized.  When finalized, new maps could have effects on some property owners in mapped 100-year floodplains. See: 100 year Floodplain Fact Sheet.

View Draft Data

New floodplain studies involve collecting and analyzing data, including: topography, hydrology analyses and hydraulic analyses.  View available draft data here:

Jefferson River Watershed Draft Hydrologic Analysis (also includes Beaverhead River, Ruby River, South Boulder River, and Indian & Mill Creeks)  

Madison River Watershed Draft Hydrologic Analysis

More draft data and information will be posted as it becomes available. 

Big Hole River Floodplain Maps

A flood study and floodplain maps for the Big Hole River were produced in 2015. The Big Hole River floodplain maps and study information will eventually be incorporated into preliminary FEMA floodplain maps at the same time as the rest of Madison County's draft floodplain maps.  Preliminary FEMA floodplain maps will go through a public review process before they are finalized.  

Come back for more information

We will update this website with new, relevant information as it is available.

Know your property's flood risk

Floodplain maps indicate areas of flood risk. Once this project is complete, updated flood risk information  will be reflected on new and updated FEMA Flood Insurance Rate Maps.  These maps will provide more accurate, current, and detailed information about flood risk areas.

Project Timeline

For questions or more information, email or call Tiffany Lyden, DNRC Floodplain Outreach Specialist (406-444-0599).