Weld County, CO Environmental Rules: Flood Zones (2026)

Chapter 23, Article XI applies to all Special Flood Hazard Areas identified for unincorporated Weld County in the Flood Insurance Study dated September 26, 2024, and its accompanying Flood Insurance Rate Maps, adopted by reference under § 23-11-250. Section 23-11-260 requires a Floodplain Development Permit for all uses in the FEMA-mapped 100-year floodplain, and § 23-11-350(B) blocks any start of construction, development, or structure erection in that floodplain until the Floodplain Administrator approves the permit. The Director of the Department of Planning Services holds the Floodplain Administrator role under § 23-11-320 and must notify an applicant of a decision within 45 days of a completed application under § 23-11-330(E).

That official must also, per § 23-11-330(I), block new construction, substantial improvement, or fill in Zones A1-A30 and AE unless it's shown the cumulative effect of the project won't raise the base flood water surface elevation more than half a foot anywhere in the county, absent a FEMA-approved conditional letter of map revision. Section 23-11-340 exempts a narrow set of open-space and emergency uses from needing a permit at all: agricultural uses like tilling, farming, irrigation, harvesting, and grazing; non-overnight recreational use; irrigation and livestock wells meeting floodplain well standards; and emergency measures such as sandbagging, so long as none of them require structures, fill, or permanent storage.