Jefferson County Flood Maps Update

Jefferson County has been working with the Federal Emergency Management Agency (FEMA) and Montana Department of Natural Resources and Conservation (DNRC) to produce new and updated 1% annual chance (100-year) floodplain maps. The project includes updating all the existing mapped floodplains in the county, and producing new floodplain maps for portions of Prickly Pear Creek and tributaries in the northern part of the county.

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 in Jefferson County are based off of data from the 1970s. For more information see: Floodplain FAQs Flood Study Process

Project Timeline

Flood Insurance Rate Maps indicate areas of flood risk. Once this project is complete, new and updated Flood Insurance Rate Maps will provide more accurate, current, and detailed data and mapping of flood risk areas. New floodplain studies involve collecting and analyzing data, including: topography, hydrology analyses and hydraulic analysis.

Project Updates

The Formal 90 day appeal and comment period ended on December 9, 2025.

Public Open House Meetings

View Preliminary Flood Insurance Rate Maps

The preliminary flood study information and maps need to go through a lengthy technical and public review process before being finalized. When finalized, new maps could have effects on some property owners in mapped floodplains.