See also Chapters 10-5, 10-5A, 10-5B, 10-5D and 10-5E.
"Floodplains" are those areas with a one percent (1%) or greater chance of flooding in any given year. 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, unless more detailed, current, and convincing evidence indicates otherwise.
(Ord. 695, 11-22-2004)
The city planner may waive the critical areas report required in section 10-5-9 of this title for developments proposed in the floodplain, but not in the floodway, if the applicable permit application contains sufficient data to verify compliance with the substantive requirements. The critical areas report shall not be waived for watercourse alterations.
(Ord. 695, 11-22-2004)
In addition to the substantive requirements of section 10-5-13 of this title, the following requirements shall apply to floodplains.
A. 
Location Of Improvements: To the extent possible consistent with the development objective, all improvements shall be located on the nonfloodplain portion of the site, if any, or on the highest ground on the site, as far as possible from the flood source.
B. 
Residential Structures: New and substantially improved residential structures shall have the lowest floor, including basement, elevated one foot (1') or more above the 100-year flood elevation. In addition, new and "substantially improved" manufactured homes (see definition in section 10-5-3 of this title) shall be securely anchored to resist flotation, collapse, and lateral movement.
C. 
Nonresidential Structures: New and substantially improved nonresidential structures shall either:
1. 
Have the lowest floor, including basement, elevated one foot (1') or more above the 100-year flood elevation; or
2. 
Together with utilities and sanitary facilities, be certified by a registered professional engineer or architect as being floodproofed, so that below one foot (1') or more above the 100-year flood level the structure is watertight and capable of resisting hydrostatic and hydrodynamic loads and buoyancy.
D. 
Fully Enclosed Areas: Fully enclosed areas below the lowest habitable floor that are not floodproofed shall be certified by a registered professional engineer or architect as designed to resist hydrostatic flood forces.
E. 
Water Supply Systems: New and replacement water supply systems shall be designed to minimize infiltration of floodwaters into the systems.
F. 
Sanitary Sewage Systems: New and replacement sanitary sewage systems and on site septic systems shall be designed to minimize infiltration of floodwaters into and discharges from the system.
G. 
New Construction And Substantial Improvements: All new construction and substantial improvements, including electrical, heating, ventilation, plumbing, and air conditioning equipment, shall be constructed using flood resistant materials and methods.
H. 
Alteration Of Natural Watercourses: Alteration of natural watercourses shall be avoided if feasible. If unavoidable, the city planner shall notify adjacent communities, the department of ecology, and FEMA prior to alteration. Any stream bank stabilization shall use soft armoring (bioengineering). Removal of vegetation and woody debris shall be minimized. The alteration shall not block side channels or diminish flood carrying capacity.
I. 
Fill And Grading: Fill and grading may be placed in areas which, in the event of a 100-year flood, would be covered with relatively static floodwaters but not in a manner which would block side channels or inhibit channel migration.
J. 
Recreational Vehicles: Recreational vehicles shall either be on the site for fewer than one hundred eighty (180) consecutive days or be fully licensed and ready for highway use.
(Ord. 695, 11-22-2004)
All developments capable of blocking floodwaters, including new construction, substantial improvements, and fill, but excluding underground improvements and conservation or habitat enhancement projects, are prohibited in the floodway unless a registered professional engineer certifies that the proposed encroachment will not result in any increase in flood levels during a 100-year flood.
(Ord. 695, 11-22-2004)
The city clerk-treasurer shall record:
A. 
The as built elevation above mean sea level of the lowest habitable floor, including basement, of all new or substantially improved structures, and whether the structure contains a basement;
B. 
Certificates of floodproofing and flood elevation; and
C. 
Permits and variances issued in accordance with this article.
(Ord. 695, 11-22-2004)
Because larger floods than the 100-year flood occur occasionally, and flood heights may be increased by manmade or natural causes, compliance with this article does not entirely guarantee against flood damages, and the city shall not be liable for flood damages that result from reliance on this article.
(Ord. 695, 11-22-2004)