A. For the purpose of the City’s Critical Areas regulations, as set forth in SMC 14.255, Floodplains are those areas that provide important flood storage, conveyance and attenuation functions and include all land within such areas that are subject to a one percent or greater chance of flooding in any given year.
B. Floodplains shall be designated by the City Planner in accordance with WAC 365-190-080(3).
1. The City Planner shall use the “areas of special flood hazard” as identified on the Federal Emergency Management Administration’s most current Flood Insurance Rate Map for the City as the indicator of where floodplains exist, useless more detailed, current, and convincing evidence indicates otherwise.
2. Floodplains shall include, at a minimum, the 100-year floodplain designations of the Federal Emergency Management Agency and the National Flood Insurance Program.
C. The City Planner may waive the critical areas report required by SMC 14.255.080 for developments proposed in the floodplain, if the applicable permit application contains sufficient data to verify compliance with the substantive requirements, except for the following developments:
1. Developments in the floodway, which is the area shown in the illustration that accompanies the definition of “floodplain” in SMC 14.100.020; and
2. Developments that result in watercourse alteration.
D. In addition to the requirements of SMC 14.255.050 and this chapter, the following requirements shall apply to floodplains:
1. To the extent possible consistent with the development objective, all improvements shall be located on the non-floodplain portion of the site, if any, or on the highest ground on the site, as far as possible from the flood source.
2. Alteration of natural watercourses, including side channels, tributaries, and channel migration zones, is to be avoided when feasible. If unavoidable, the City Planner shall notify adjacent communities, the Department of Ecology, the State Department of Fish and Wildlife, and FEMA prior to alteration. Any stream-bank stabilization shall consider the use soft armoring or best available armoring science.