A. Description: Located within special flood hazard areas are areas designated as floodways. The floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential.
B. Restrictions On Development In Floodways: No floodplain development shall be permitted in any designated floodway except new construction solely for the replacement or substantial improvement of an existing residential or commercial structure and accessory buildings in conjunction with an existing residential or commercial use, and except as otherwise provided in this section. Additionally, access roads may be permitted to cross the floodway where no alternative access ways which do not encroach on the floodway are possible. All floodplain development permitted in a floodway shall comply with the following standards:
1. Floodplain development based on a no-rise certification.
a. For approval of a floodplain development permit for floodplain development within a floodway based on a no-rise certification, a qualified professional engineer licensed by the State of Idaho must submit a no-rise certification which demonstrates, through hydrologic and hydraulic analyses prepared in accordance with standard engineering practice (with supporting technical data), that the proposed floodplain development would not result in an increase in flood levels during the occurrence of the base flood.
b. All foundations for new construction and substantial improvement shall be designed by a qualified engineer licensed by the State of Idaho and constructed to withstand the hydrodynamic and hydrostatic pressures during the discharge of the base flood. If flood velocities are excessive (greater than four feet (4') per second), foundation systems other than solid foundation walls are required so that obstructions to damaging flows are minimized.
2. Floodplain Development Based On An Approved CLOMR: A Conditional Letter of Map Revision (CLOMR) approved by FEMA may be submitted with a floodplain development permit application in lieu of a no-rise certification. A Letter of Map Revision (LOMR) must be obtained within six (6) months of the start of construction of the proposed floodplain development.
3. On existing lots of record where sufficient lot area is available, all floodplain development, including fill, new construction, and substantial improvements to existing structures shall occur outside of the floodway.
4. Construction pursuant to subsection 8.7.204(I), "Alteration And Maintenance Of Watercourses", of this article is allowed in floodways with a floodplain development permit.
5. Encroachments:
a. A floodplain development permit shall be required for all encroachments, regardless of whether or not the encroachment is in aid of navigation.
b. All permits required by other agencies with jurisdiction shall have been issued before a floodplain development permit may be issued.
c. The Director shall issue a floodplain development permit for an encroachment if the applicable requirements of section 8.7.203 of this article have been met.
6. A structure that increases the level of the base flood may be constructed in the floodway only if the Director finds that the structure would serve a substantial public interest, and the applicant has applied for a conditional FIRM and floodway revision, has fulfilled applicable FEMA requirements for such revisions, and has received the approval of the Federal Insurance Administrator. (Ord. 493, 6-9-2016; amd. Ord. 545, 10-3-2019; Ord. 561, 12-17-2020)