Iowa DNR, Floodplain Development


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- Drainage Areas of Iowa Streams Bulletin #7 (Report Number HR-029)
 

FLOOD PLAIN OR FLOODWAY DEVELOPMENT: WHEN APPROVAL IS REQUIRED

Buildings and Associated fill

When Department Approval is Required Per IAC Chapter 71
Approval by the department for construction, use and maintenance of "buildings" as defined in 567-Chapter 70 and for placement of fill is required as described in the following thresholds.

71.7(1) Building and placement of associated fill in urban areas. In urban areas as defined in these rules approval is required for construction, use and maintenance of buildings in the floodway or flood plain of any stream draining more than 2 square miles at the location of the structure as follows:

  1. New construction including fill for development purposes. Approval is required for construction of any new building. New construction includes replacement or relocation of an existing building. New construction also includes placement and grading of fill materials in a manner that would create an elevated building site.

  2. Additions to existing buildings. Approval is required for any addition which increases the original floor area of a building by 25 percent or more. All additions constructed after July 4, 1965, shall be added to any proposed addition in determining whether the total increase in original floor space would exceed 25 percent.

  3. Lowering or elevating. Approval is required for lowering a floor of a building. Approval is not required for elevating an existing building. However, when a building is elevated the lowest floor should be elevated to the appropriate minimum protection level stated in 567-subrule 72.5(1). The department, upon request, will cooperate in determining the minimum protection level for a person who proposes to elevate a building.

  4. Reconstruction. Approval is required for reconstruction of any portion of a building if the cost of reconstruction exceeds 50 percent of the market value of the existing building or if reconstruction will increase the market value by more than 50 percent.

71.7(2) Buildings and associated fill located within 2 miles of an urban area. The thresholds for buildings and associated fill in subrule 71.7(1) shall apply to rural areas within 2 miles of municipal corporate limits.

71.7(3) Buildings and associated fill in all other rural areas. In rural areas not covered by 71.7(1) the thresholds for approval of buildings and associated fill are the same as in 71.7(1) except that approval is required only when the drainage area at the location of the structure is more than 10 square miles.

71.7(4) Buildings and associated fill adjacent to or downstream from impoundments. Approval is required for new construction, additions, lowering, or reconstruction and associated fill as described in 71.7(1) without regard to the drainage area if the proximity of the building to a dam regulated by the department is as follows:

  1. Adjacent to impoundment. Approval is required for a building and associated fill adjacent to an impoundment if the lowest floor level including any basement is lower than the top of the dam.

  2. Downstream from dam. Approval is required for a building and associated fill downstream from a dam at any location where flooding can be reasonably anticipated from principal or emergency spillway discharges. If the dam does not substantially comply with high hazard criteria in these rules, approval is required for a building and associated fill at any location where flooding can be reasonably anticipated from overtopping and failure of the dam.

Application Forms, Checklists & Guidance:

Application Form(s)
*.pdf
Joint Application Form
PDF File Format
National Flood Insurance Program: Elevation Certificate and Instructions
PDF File Format
National Flood Insurance Program: Floodproofing Certificate for Non-Residential Structures
PDF File Format
 
Application Guidance
*.pdf
Procedural Guide for Buildings and Houses
PDF File Format
 
Application Checklist(s)
*.pdf
Gaining Approval for Buildings and Houses
PDF File Format

Aerial photographs can be obtained online at: http://ortho.gis.iastate.edu/search.html.

 

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