Linn County, IA Environmental Rules: Flood Elevation Requirements (2026)

All new or substantially improved residential structures shall have the lowest floor, including basements, utility systems, such as heating and cooling equipment, water heaters and similar devices, elevated a minimum of two feet above the base flood elevation. 2.Construction shall be upon compacted fill which shall, at all points, be no lower than two feet above the base flood elevation and extend at such elevation at least 18 feet beyond the limits of any structure erected thereon. 3.Alternate methods of elevating (such as piers or extended foundations) may be allowed, where existing topography, street grades, or other factors preclude elevating by fill. In such cases, the methods used must be adequate to support the structure as well as withstanding the various forces and hazards associated with flooding. 4.All new residential structures shall be provided with a means of access which will be passable by wheeled vehicles during the base flood. However, this criterion shall not apply where the zoning administrator determines, based on information provided by the applicant, there is sufficient flood warning time for the protection of life and property. When estimating flood warning time, consideration shall be given to the criteria listed in 567-75.2(3), Iowa Administrative Code.