FEMA flood zone rules in Jefferson County, CO — also called floodplain regulations or special flood hazard area (SFHA) rules — determine flood insurance requirements and elevation standards for new construction.
Jefferson County participates in the FEMA National Flood Insurance Program (NFIP) under FIS 08059CV001D and administers Section 30 (Floodplain Overlay District) of the Zoning Resolution. A Floodplain Development Permit is required before any work in a Special Flood Hazard Area mapped on the FEMA FIRM. Substantial improvements (50% of market value, cumulative over 5 years) trigger full compliance. Colorado state rules at 2 CCR 408-1 require 1 ft of freeboard above base flood elevation for residential structures.
Jefferson County is an NFIP-participating community covered by FEMA Flood Insurance Study 08059CV001D (revised December 20, 2019). Floodplain rules are codified in Section 30 (Floodplain Overlay District) of the Jefferson County Zoning Resolution, with stormwater design governed by the Storm Drainage Design and Technical Criteria manual. Any development - new construction, fill, grading, substantial improvement, or storage of materials - in a Special Flood Hazard Area (Zone A, AE, AO, AH, or floodway) requires a Floodplain Development Permit, applied for through the Jefferson County Citizen Portal before a building permit can issue. Major mapped floodplains include Clear Creek (with channelization in and near Golden), Bear Creek, North Turkey Creek, and tributaries of the South Platte. The 'substantial improvement' rule applies when the cost of repair, reconstruction, or improvement equals or exceeds 50% of the structure's market value; Jefferson County uses a 5-year cumulative window starting from the initial permit. Per Colorado state rule 2 CCR 408-1 (Colorado Water Conservation Board), residential structures in the SFHA must have the lowest floor at least 1 foot above base flood elevation (1 ft of freeboard). Federal NFIP rules at 44 CFR Parts 59-60 also apply. Contact Planning & Zoning at 303-271-8700.
Development in a Special Flood Hazard Area without a Floodplain Development Permit violates Section 30 of the Zoning Resolution and can trigger stop-work orders, after-the-fact permitting, structure removal, or corrective action. Cumulative improvements that breach the 50% substantial-improvement threshold without compliant elevation can disqualify the property from NFIP flood insurance. Federal sanctions under 44 CFR Part 60 apply if the county is found out of NFIP compliance.
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