(A) The flood profiles, flows and floodway data in the regulatory floodway study, referenced in § 152.004, must be used for analysis of the base conditions. If the study data appears to be in error or conditions have changed, IDNR-OWR shall be contacted for approval and concurrence on the appropriate base conditions data to use.
(B) If the 100-year regulatory floodway elevation at the site of the proposed construction is affected by backwater from a downstream receiving stream with a larger drainage area, the proposed construction shall be shown to meet:
(1) The requirements of this section for the 100-year frequency flood elevations of the regulatory floodway conditions; and
(2) Conditions with the receiving stream at normal water elevations.
(C) If the applicant learns from IDNR-OWR, local governments, or a private owner that a downstream restrictive bridge or culvert is scheduled to be removed, reconstructed, modified, or a regional flood control project is scheduled to be built, removed, constructed or modified within the next five years, the proposed construction shall be analyzed and shown to meet the requirements of this section for both the existing conditions and the expected flood profile conditions when the bridge, culvert or flood control project is built.
(Ord. 3187, passed 1-22-19) Penalty, see § 152.999