Upper Goose Creek and Twomile Canyon Creek
Floodplain Mapping Update
The city has contracted with ICON Engineering to develop updated floodplain maps for Upper Goose Creek and Twomile Canyon Creek. Anderson Consulting Engineers is providing peer review of the engineering study.The Urban Drainage and Flood Control District (UDFCD) is a co-sponsor of this project and is also providing review. The following figure shows the study limits:
Floodplain mapping studies provide the basis for flood management by identifying the areas subject to flooding. This information is essential for determining areas where human safety is threatened and property damage is likely. Floodplain maps must be updated periodically to reflect changes in the floodplain resulting from land development, flood mitigation improvements, new study technologies and the impacts of major floods that may have occurred.
Upper Goose Creek and Twomile Canyon Creek were first studied by Greenhorne & O'Mara in 1987. The resulting Flood Hazard Area Delineation (FHAD) delineated the 100-year floodplain along these creeks.The Flood Insurance Study (FIS) and Flood Insurance Rate Map (FIRM) approved for these creeks were originally based on the 1987 FHAD and included a federally-regulated one foot rise floodway. In 1989, Love and Associates delineated the High Hazard Zone and City of Boulder Conveyance Zone (1/2 foot rise floodway).The delineations were based on the hydraulic models used in the 1987 FHAD.
In 1991, the city commissioned Love and Associates to restudy Twomile Canyon Creek. Based on that study, FEMA issued a Letter of Map Revision (LOMR) for Twomile Canyon Creek on April 5, 1994.The limit of the LOMR was between the confluence of Twomile Canyon Creek and Upper Goose Creek to just upstream of Linden Avenue. In 2004, McLaughlin Water Engineers, Ltd. updated flood mapping for Goose Creek to reflect channel improvements.The limits of the LOMR for this project extended from 30th Street to approximately 1,900 feet upstream of Folsom Street.
The following project hydrology and field surveys have been conducted:
Project Schedule and Next Steps
The anticipated next steps for this project include:
- Water Resources Advisory Board - January 2014
- Planning Board - First Quarter 2014
- City Council - Second Quarter 2014
- FEMA Submittal - Second Quarter 2014
Find out if your property is located in a floodplain using the interactive floodplain map.
Read the Frequently Asked Questions to learn more.
For property-specific information about the land development requirements for all floodplain zones, contact Planning & Development Services at 303-441-1880 or
For more information, please contact
, Engineering Project Manager, at 303-441-4232.
Last Updated on Monday, 17 June 2013 14:25