Upper Yellowstone Park, Stillwater, Carbon Counties

On June 13, 2022, Park, Stillwater, and Carbon Counties experienced damaging floods. Late snowfall mixed with heavy rains and warmer temperatures sent high velocity floodwaters and devastated communities throughout these three counties. High water and heavy debris in all three counties scoured banks and changed the topography of the rivers and streams. In connection with this historic flood the counties collaborated with DNRC, and FEMA to update the floodplain maps.

 For permitting information due to the flood event please click below for the DNRC permit page and access to the quick guide. 

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For additional information on what data to use for permitting please click here to review DNRC interim guidance that was developed for flood affected communities.

Community information

History of Floodplain Maps:

Park County has had a few updated flood studies throughout the last 10 years but has not had a full study of the entire county. Most of the updated data was collected in 2005 for a small section of the Yellowstone River and a few map revisions that were included into the digitization effort in 2011. Most of the rest of the maps are based on data that was collected in the late 1970s.

2022 Flood Study Phase I: 

DNRC applied for a grant from FEMA to begin an updated flood study. This project would include the Lidar, Survey, and Hydrology for the Yellowstone River, Shields River, and tributaries through Park County.

 

2023 Flood Study Phase II:

To complete the rest of the study work DNRC would apply for a grant from FEMA in the summer of 2023. This project would include the Hydraulics, and Floodplain Mapping for the Yellowstone River, Shields River, and tributaries through Park County.  

History of floodplain maps:

Stillwater County has had some minor updates to the floodplain maps. In 2013 an updated study was conducted on the Yellowstone River. Two LOMRs were conducted in 2021, but the rest of the maps are based on data collected in the late 1980s.

2022 Flood Study phase I:

DNRC applied for a grant from FEMA to begin an updated flood study. This project would include the Lidar, Survey, and Hydrology for the Yellowstone River, Stillwater River, and tributaries through Stillwater County.  

2023 Flood Study phase II:

To complete the rest of the study work DNRC would apply for a grant from FEMA in the summer of 2023. This project would include the Hydraulics, and Floodplain Mapping for the Yellowstone River, Stillwater River, and tributaries through Stillwater County.  

History of floodplain maps:

Carbon County floodplain maps were modernized through a Digitized Flood Insurance Rate Map (DFIRM) project in 2012. The maps were converted from paper to the digital environment. Most of the mapped floodplains in the county are still based off flood studies from the late 1970s and early 1980s. The 2012 DFIRM project entailed digital conversion of the effective floodplains in the county, except for revised hydraulics and mapping on 9 miles of the Clarks Fork of the Yellowstone (upstream from the
Carbon/Yellowstone County border). This revision, however, did not include updated hydrology or survey data. In 2017 a Partial Mapping Revision (PMR) was completed for the portion of the Yellowstone River in the county. The PMR leveraged US Army Corps of Engineers information from a Yellowstone River corridor study and updated floodplain mapping in Stillwater and Yellowstone Counties to update and replace the approximate floodplain mapping on the Carbon County side of the Yellowstone River with enhanced and floodway mapping.

2019 Flood Study: Project was put on hold due to major flooding and changes to the streams.

2022 Flood Study (phase I):

DNRC applied for a grant from FEMA to begin an updated flood study. This project would include the Lidar, Survey, and Hydrology for the Yellowstone River, Clarks Fork of the Yellowstone River, and Rock Creek through Carbon County.  

2023 Grant Application (phase II):

To complete the rest of the study work DNRC would apply for a grant from FEMA in the summer of 2023. This project would include the Hydraulics, and Floodplain Mapping for the Yellowstone River, Rock Creek, Clarks Fork of the Yellowstone and tributaries through Carbon County.  

Phase I Flood Study:

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Tentative Project Timeline:

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