FEMA administers the National Flood Insurance Program (NFIP). In exchange for access to this program, which includes both flood insurance products for homeowners as well as access to significant financial support for local governments, Boulder County adopts and enforces FEMA-approved floodplain regulations. These regulations, found in Section 4-400 of the Boulder County Land Use Code, apply to land located in unincorporated Boulder County that lies within the Floodplain Overlay Zoning District, the extent of the mapped 100-year floodplain.
Through enforcement of current regulations, preservation of floodplains, and development of hazard mitigation and emergency response plans, Boulder County has been able to preserve flood prone areas, prevent adverse impacts and unwise uses in the floodplain.
Collaborative work by Boulder County with outside agencies through stream enhancement, mitigation, and flood control projects has demonstrated a focus on accommodating floods instead of controlling them.
If you are a property owner and want to build on your property, you may need to meet certain requirements.
Buildings located in the floodplain overlay district may be required to be flood-proofed. Flood-proofing includes methods such as elevating the structure’s lowest flood to or above flood protection elevation, building with flood-resistant materials, and installation of flood vents.
Substantial Damage/Substantial Improvement
FEMA regulations specify that Substantial Improvement of existing buildings (remodeling, rehabilitation, improvement, or addition) or buildings that have sustained Substantial Damage must be brought into compliance with floodproofing requirements for new construction.
A structure is considered Substantially Damaged when the cost of restoring the structure would equal or exceed 50% of the pre-damaged market value of the structure.
A structure is considered Substantially Improved when an improvement is made that equals or exceeds 50% of the market value of the structure prior to the start of work.
To make a Substantial Improvement/Substantial Damage determination, the county compares the cost of the proposed improvement or repairs to the market value of the building (except land, accessory structures, landscaping, bridges, water wells, onsite wastewater treatment systems, and other incidental items). If the resulting ratio equals or exceeds 50%, the existing building must be brought into compliance with the floodplain management requirements for new buildings.
Projects involving buildings in the floodplain usually require a Floodplain Development Permit and Building Permit.
Private Access Bridges & Culverts