15.04.160 Floodway/floodway fringe.
Special restrictions with respect to floodways and floodway fringe areas shall be as follows:
A. Floodway. Located within areas of special flood hazard established in RMC 15.04.040 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following are not permitted in the floodway: structures, developments, or landfills, other than for shoreline protective structures, bridges, roads, trails, and railroads.
1. No Rise Standard. Prohibit encroachments, including fill, new construction, substantial improvements, and other development, unless certification by a registered professional engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels during the occurrence of the base flood discharge.
2. All Other Building Standards Apply in the Floodway. If subsection A of RMC 15.04.160 is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of RMC 15.04.
B. Floodway Fringe Restrictions. The following are not permitted in a floodway fringe:
1. Except in areas designated “urban environment” in the Redmond shoreline master program, any structure, development or landfill which would: reduce the natural floodwater storage capacity of the area of special flood hazard; pollute or contribute materially to the turbidity of floodwater at the base flood stage; significantly change the existing base flood hydraulic characteristics; or alter the temperature characteristics of the water body unless an improvement in fish habitats would result.
2. Any residential structure which is not fully protected from water damage at the base flood elevation by having the lowest floor raised at least one foot above the base flood elevation.
3. Any nonresidential structure which does not meet the elevation or floodproofing requirements for nonresidential or critical facilities standards of this chapter. (Ord. 3006 § 2 (part), 2020: Ord. 2737 § 2 (part), 2014: Ord. 2202 § 1 (part), 2004: Ord. 863 § 9, 1979).