Floodplain Remapping Project

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Official Floodplain Map

The interactive web map (use the button above) shows detailed flood risk zones and related FEMA map amendments that are currently regulated throughout unincorporated Boulder County as Floodplain Overlay Zoning District. This map will update as new FEMA maps become effective throughout Boulder County and as the Boulder County Board of County Commissioners (BOCC) adopts best available information.

The Boulder County Regulatory Flood Risk Zones were updated on March 26, 2024, to reflect changes to the Floodplain Overlay District based on FEMA’s Physical Map Revision reflecting the Colorado Hazard Mapping Program (CHAMP) study. The zoning map amendments were adopted by the BOCC via Docket Z-23-0001.

View Preliminary FIRMS

In July 2023, FEMA released revised Preliminary Flood Insurance Rate Maps (Preliminary FIRMs). The revised Preliminary FIRMs differ from the already adopted CHAMP maps in eight areas where FEMA approved changes submitted during FEMA’s 2020 and 2021 appeal periods. We expect the revised Preliminary FIRMs will become the effective FIRMs in October 2024. At that time, the updated CHAMP mapping will be used for flood insurance purposes.

Visit the interactive web map (use button above) to view FEMA’s Revised Preliminary Flood Insurance Rate Maps (FIRMs) for stream reaches studied by CHAMP, as well as proposed changes to the Boulder County Floodplain and Floodway.

New Information

• Docket Z-23-0001 – Zoning Map Amendments to the Floodplain Overlay District
• Subscribe – Receive timely information by email

About the CHAMP maps

Following the 2013 Flood, the Colorado Water Conservation Board (CWCB) initiated a program to re-map the predicted 1% annual chance flood zone (100-year floodplain) of the most affected waterways (shown in the image above). The program was called the “Colorado Hazard Mapping Program,” or CHAMP. Draft map data and related flood studies for the CHAMP– studied reaches were adopted by the Board of County Commissioners (BOCC) through Docket Z-17-0001 and Docket Z-17-0002. In September 2019, FEMA released Preliminary Flood Insurance Rate Maps (FIRMs) for the same CHAMP reaches, refining the draft maps. The Preliminary FIRMs were adopted by the BOCC, replacing the draft map data via Docket Z-19-0001 to allow the county to base floodplain regulations on the best available data.

In 2020 and 2021, FEMA ran appeal periods, where anyone had the opportunity to appeal or comment on the Preliminary FIRMs. Following FEMA’s resolution of the appeals, revised Preliminary FIRMs were released in July 2023. Boulder County will align the Boulder County Floodplain and Floodway with the revised Preliminary FIRMs through Docket Z-23-0001. In October 2024, the revised Preliminary FIRMs will become effective for flood insurance purposes.

Please contact the Floodplain Management Team (info below) with questions or to learn more about the floodplain mapping changes.