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Floodplain Administration

FEMA has revalidated the previous Letter of Map Revision (LOMR) which amended the floodplain maps for the Blackfoot and Clark Fork Rivers following the removal of Milltown and Stimson Dams effective July 29, 2015. For additional information please contact the floodplain administrator or review the LOMR here.

Floodplain status of County parcels per the FEMA floodplain maps can be checked online using the Chrome internet browser available free here:

By entering the parcel's address or geocode number, you can view the approximate boundaries of the July 6, 2015 FEMA maps including the July 29, 2015 Milltown LOMR:

The floodplain administration program includes permitting and regulatory work associated with the floodplain in Missoula County outside Missoula City limits*. Below are links to permits and regulations associated with the floodplain program.

For further information, please contact the Missoula County Floodplain Administrator at 406-258-4841 or by email


*For City floodplain administration, contact the City Development Services at 552-6630 and visit the website here.

Missoula County & City of Missoula Floodplain Maps

FEMA Digital Flood Insurance Rate Maps (DFIRM)

The maps are also available on DVD for $1.00 or you can also bring in a flash drive and we can load them maps on it for free.

FEMA's Revalidation Letter lists Letter of Map Change (LOMC) issued under older floodplain maps and reaffirmed for the July 6, 2015 DFIRM. The Revalidation Letter does not list LOMCs that have been incorporated, superseded by new or revised mapping or no longer valid. The Revalidation Letter is considered legally binding, in the same manner as an original LOMR-For LOMA, provided that a copy of the original determination accompanies the Revalidation Letter.

More information is provided in the Flood Insurance Study documents.

Information for property owners that are newly mapped into the floodplain.

Past Projects:

Clark Fork River Channel Migration Zone - Pilot Study

When someone has lived along a stream for a few years and it doesn’t appear that the stream has moved, they may be lulled into thinking that it might stay that way forever.  But the fact is that streams naturally migrate across their floodplains over time and in response to large events such as floods, debris or ice jams.  Former active river channels are readily visible in aerial photos of the Missoula Valley.  Historic photos show a long term pattern of channel migration.  Despite our best efforts to control them, streams often reclaim their former channels and floodplains, potentially resulting in catastrophic loss of life and property.   

In December, 2009 the Missoula Water Quality District released a pilot channel migration study for a stretch of the Clark Fork River downstream of Missoula to Huson.  The study documents where the channel has been historically - and where it may be again within the next 100-years.  The study and associated maps are available for download here:

Permits and Forms

Other Related Links:

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