Douglas County, CO Environmental Rules: Flood Elevation Requirements (2026)

Douglas County's Floodplain Overlay District (Part 18 of the Zoning Resolution) sets the construction standard above the base flood elevation (BFE) shown on the county's FEMA Flood Insurance Rate Map. Under § 1-1811(3), new residential construction and substantial improvements must have the lowest floor, including the basement, plus all electrical, heating, ventilation, plumbing and air-conditioning equipment, elevated to one foot above the BFE, a freeboard margin. A registered Colorado professional engineer, architect, or land surveyor must certify the as-built elevation to the Floodplain Administrator, a role held by the Public Works Engineering Director.

Nonresidential buildings under § 1-1811(4) get an alternative: dry floodproof to one foot above BFE with watertight, impermeable walls engineered to resist hydrostatic loads, again certified by a professional engineer or architect. Manufactured homes under § 1-1811(6) need the same one-foot elevation on a permanently anchored foundation, or 36-inch reinforced piers in an existing manufactured-home park. Critical facilities defined in § 1-1816, hospitals, police and fire stations, schools, and emergency operations centers, are held to a stricter two-foot freeboard above BFE (or two feet of floodproofing) and must keep continuous non-inundated access for evacuation and emergency response.

Any of this construction first needs a Floodplain Development Permit under § 1-1817, applied for through the Floodplain Administrator on Engineering Services Division forms before ground is broken. A variance from the Floodplain Administrator under § 1-1818 is limited to lots of a half-acre or less surrounded by existing structures already below BFE, or historic-structure rehabilitation, and anyone granted one gets written notice that their flood-insurance premium will reflect the lower elevation. Appeals from Floodplain Administrator decisions go to the Board of Adjustment under § 1-1819.