Lead paragraph
Adopt updated floodplain boundaries and integrate into short and long-range planning citywide.
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4.5Update Floodplain Boundaries
Progress
- Not started
- Planning
- Implementation
- Continuous
Late
Preliminary FIRMs to replace the 2012 FIRMs has been delayed by FEMA due to an unresolved appeal. These maps now plan to be effective by summer 2024. These maps replace the 2012 FIRMs for St. Vrain Creek and Left Hand Creek. The floodplain maps for 2 of the remaining creeks that run through Longmont will be updated in 2024 (Spring Gulch No1 and No 2). Dry Creek 1 will be updated as soon as the budget will allow.
Description
There are 5 creeks with floodplain maps within Longmont's jurisdiction. Revisions to St. Vrain and Left Hand Creeks are complete. Flood Insurance Studies (including maps and models) for both Weld and Boulder Counties became FEMA effective on September 26 and October 24, 2024, respectively. Spring Gulch No. 2 is in review. Final floodplain delineations for Spring Gulch No. 1 will be completed in Q2 of 2026.. The update of Dry Creek No. 1 will also begin in 2026.
Tasks
What's left to do?
- 12/31/2025
Dry Creek Floodplain Study
What are we doing?
- 9/30/2024
Spring Gulch No. 2 Floodplain Study
Mapping is not yet completed. Hydrology review is now completed.
What has been done?
- 12/31/2025
Spring Gulch No. 1 Floodplain study
This project is nearly complete. Includes new models and mapping from St. Vrain creek to TerryLake Detention pond north of Hwy 66.
- 07/24/2025
Preliminary FIRMs
New maps effective in October 2024 for both Weld and Boulder Counties
This study will now start in January 2026