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DNRC Headquarters
1539 Eleventh Ave. Helena, MT 59601
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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 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.  View study 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 in Jefferson County are based off of data from the 1970s.  For more information see:  Floodplain FAQs  Flood Study Process

Public Open House Meetings Held
June 21, 2022 in Montana City | 6:30-8:30pm | Montana City Fire Station | view slides | view video recording
June 23, 2022 in Boulder | 6:30-8:30pm | County Fairgrounds Hall | 21 N. Whitetail Rd | view slides | view video recording

Jefferson County and Montana DNRC hosted public open house meetings in June about draft floodplain maps in the northern and central portion of Jefferson County.  

Additional public meetings will be scheduled later in summer or fall to share draft floodplain maps for the southern part of Jefferson County.  

View Draft Maps 


*please be patient while the data loads on the viewer*

The draft 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. See: 
100 year Floodplain   Floodway (within 100 year floodplain)  500 year Floodplain

View Draft Reports 

Hydrology Reports

Boulder R & Prickly Pear Cr mainstems & tributaries; and Jefferson R tributaries (appendices available upon request) - prepared by Pioneer Technical Services
Jefferson River (appendices available upon request) - prepared by Michael Baker

Hydraulic Reports 

Boulder River (appendices available upon request) - prepared by Pioneer Technical Services
Boulder River tributaries (appendices available upon request) - prepared by Pioneer Technical Services
Prickly Pear Creek and tributaries (appendices available upon request) - prepared by Morrison-Maierle
Jefferson River tributaries (appendices available upon request) - prepared by DOWL
Jefferson River
 (appendices available upon request) - prepared by Great West Engineering

Come back for more information

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

Know your property's flood risk

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 Timeline

Project Timeline Jefferson Floodplain Maps Update 04-2022.jpg


More Info

Floodplain FAQs
Flood Study Process

Jefferson County

Megan Bullock
Floodplain Administrator
(406) 225-4126

City of Boulder

Ellen Harne
Floodplain Administrator
(406) 225-9629


DNRC Contacts

Tiffany Lyden
DNRC Outreach Specialist
(406) 444-0599

Nadene Wadsworth

DNRC Outreach Specialist
(406) 444-6732