Casper, WY Environmental Rules: Flood Zones (2026)

Chapter 17.20 of the Casper Municipal Code, 'FC Major Flood Channels and River Banks,' regulates every special flood hazard area (SFHA) mapped by FEMA inside city limits. Section 17.20.040(B) adopts by reference the Flood Insurance Study for Natrona County, Wyoming, dated May 18, 2015, along with its accompanying Flood Insurance Rate Maps, and subsection (C) requires a development permit before any structure or land use in an SFHA can be located, altered, or changed. Section 17.20.050 names the community development director as the city's floodplain administrator, responsible for administering the chapter and the relevant parts of 44 CFR, the National Flood Insurance Program regulations.

Section 17.20.060 lists that administrator's duties: reviewing every permit application to confirm a proposed site is reasonably safe from flooding, approving or denying development permits, confirming that federal, state, and local approvals like Clean Water Act Section 404 sign-offs are in hand, interpreting disputed SFHA boundaries, and notifying the Wyoming Office of Homeland Security and FEMA before any watercourse is altered or relocated. Section 17.20.070 spells out what an applicant must submit: scaled plans showing the location, dimensions, and elevation of proposed structures and any landscape alteration relative to the SFHA, elevation data for the lowest floor of new or substantially improved structures, and an engineer's or architect's floodproofing certification for nonresidential buildings.

The administrator weighs ten factors under subsection (B), including danger to life and property, susceptibility to flood damage, and availability of non-flood-prone alternative sites, before approving or denying the permit. Appeals of a permit denial go to the planning and zoning commission and then to district court.