(A) Except as provided in division (E) of this section, encroachments, including fill, new construction, substantial improvements, fences and other development are prohibited in the regulatory floodway unless certification by a registered professional engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that such encroachment will not result in any increase in flood levels during the occurrence of the base flood discharge.
(B) Any fill permitted to be placed in the regulatory floodway shall be designed to be stable under conditions of flooding, including rapid rise and rapid drawdown of floodwaters, prolonged inundation, and flood-related erosion and scour.
(C) If permitted, fences shall not cause any rise in base flood elevation and are subject to the no-rise and CLOMR provisions of divisions (A) and (D) of this section.
(D) Applicants shall obtain a Conditional Letter of Map Revision (CLOMR) from FEMA before an encroachment, including fill, new construction, substantial improvement, fences, or other development, in the regulatory floodway is permitted that will cause any increase in the base flood elevation unless the development causes a temporary encroachment and the conditions in division (E) of this section are satisfied.
(E) Temporary encroachments in the regulatory floodway for the purposes of capital improvement projects (including bridges) may be allowed even if the encroachment results in an increase in flood levels during the occurrence of the base flood discharge, and without obtaining a CLOMR, when:
(1) The project is limited as to duration with the days and dates that the structure or other development will be in the regulatory floodway specified in the development permit;
(2) Accessory structures (i.e. construction trailers) are restricted from the regulatory floodway;
(3) The project limits placement of equipment and material in the regulatory floodway to that which is absolutely necessary for the purposes of the project;
(4) The project includes a flood warning system sufficient to allow equipment to be evacuated from the regulatory floodway and placed outside the area of special flood hazard in the event of imminent flood;
(5) The project applicant identifies any insurable structures affected by temporary changes to the area of special flood hazard or base flood elevation and notifies owners of any increased risk of flooding; and
(6) The project applicant is provided with written notification that they may be liable for any flood damages resulting from the temporary encroachment.
(F) Projects for stream habitat restoration may be allowed without certification by a registered professional civil engineer provided:
(1) The project qualifies for a Department of the Army, Portland District Regional General Permit for Stream Habitat Restoration (NWP-2007-1023);
(2) A qualified professional (a registered professional engineer; or staff of Natural Resources Conservation Service; the county; or fisheries, natural resources, or water resources agencies) has provided a feasibility analysis and certification that the project was designed to keep any rise in 100-year flood levels as close to zero as practically possible given the goals of the project;
(3) No structures would be impacted by a potential rise in flood elevation; and
(4) An agreement to monitor the project, correct problems, and ensure that flood carrying capacity remains unchanged is included as part of the local approval.
(G) All permitted and substantial improvements shall comply with all applicable flood hazard reduction provisions of this chapter.
(Ord. 259, passed 3-17-2011; Ord. 286, passed 12-7-2017) Penalty, see § 151.999