Background
The 2013 Flood event caused widespread damage along waterways throughout Boulder County and other areas of the state. In response, the State of Colorado took steps to bolster long-term planning and resiliency efforts by funding Colorado Hazard Mapping Program (CHAMP), managed by the Colorado Water Conservation Board (CWCB). CHAMP is updating local hazard information, including producing new regulatory floodplain maps for the most affected waterways.
The county’s Floodplain Overlay District is comprised of both the FEMA Floodplain and Floodway and the Boulder County Floodplain and Floodway. The county has already incorporated draft CHAMP data into the Boulder County Floodplain and Floodway via Resolutions 2017-68, 2018-78, and 2020-11.
In July 2023, FEMA released revised Preliminary Flood Insurance Rate Maps (Preliminary FIRMs) based on the CHAMP remapping efforts. The revised Preliminary FIRMs differed from the already adopted draft CHAMP maps in eight areas where FEMA approved changes submitted during FEMA’s 2020 and 2021 appeal periods. The appeals included a Scientific Resolution Panel for portions of Lefthand Creek. We expect the revised Preliminary FIRMs will become the future effective FIRMs in the autumn of 2024.
In accordance with Section 4-403 of the Land Use Code, it is necessary to amend the Boulder County Floodplain to incorporate the changes FEMA made during their appeal resolution process. Aligning the Boulder County Floodplain and Floodway with the revised Preliminary FIRMs will reflect the best available flood hazard data. Specifically, staff propose removing Boulder County Floodplain and Floodway for stream reaches included in the CHAMP study, such that the FEMA FIRM will be the only effective regulatory floodplain for CHAMP reaches after the FEMA map update.