International Residential Code Section R322.1.4 is hereby amended to read as follows:

R322.1.4 Establishing the design flood elevation. The design flood elevation shall be used to define flood hazard areas. At a minimum, the design flood elevation shall be one foot above the higher of the following:

1. The base flood elevation at the depth of peak elevation of flooding, including wave height, that has a 1 percent (100-year flood) or greater chance of being equaled or exceeded in any given year, or

2. The elevation of the design flood associated with the area designated on a flood hazard map as identified by the Federal Emergency Management Agency in an engineering report entitled “The Flood Insurance Study (FIS) for King County, Washington, and Incorporated Areas,” dated August 19, 2020, and any revisions thereto, with the accompanying Flood Insurance Rate Maps (FIRMs), dated August 19, 2020, and any revisions thereto. The adopted flood hazard map and supporting data are hereby adopted by reference and declared to be part of this section.

R322.1.4.1 Determination of design flood elevations. If design flood elevations are not specified, the building official is authorized to require the applicant to comply with either of the following:

1. Obtain and reasonably use data available from a federal, state or other source.

2. Determine the design flood elevation and/or floodway in accordance with City of Bellevue LUC 20.25H.175A and Surface Water Engineering Standards, Section D4-04.5, “Floodplain/Floodway Analysis” in order to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice and complied with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Studies, analyses and computations shall be submitted in sufficient detail to allow thorough review and approval.

R322.1.4.2 Determination of impacts. In riverine flood hazard areas where design flood elevations are specified but floodways have not been designated, the applicant shall provide a floodway analysis that demonstrates that the proposed work will meet the City of Bellevue Surface Water Engineering Standards, Section D4.04.5, “Floodplain/Floodway Analysis.”