1. Statutory authorization. The legislature of the state in Idaho Code, §§ 46-1020—46-1024, authorized local government units to adopt a floodplain map and floodplain management ordinance that identifies floodplains and sets forth minimum development requirements in floodplains that are designated to promote the public health, safety and general welfare of its citizenry.
2. Purpose. The purpose of this zone is to promote the public health, safety, and general welfare, and to minimize public and private losses due to flood conditions in specific areas by methods and provisions designed for:
   1. Restricting or prohibiting uses which are dangerous to health, safety, and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities;
   2. Requiring that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction;
   3. Controlling the alteration of natural floodplain, stream channels and natural protective barriers, which help accommodate or channel floodwaters;
   4. Controlling filling, grading, dredging and other development which may increase flood damage; and
   5. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards in other areas.
3. Definitions. For the purpose of this section certain terms are defined as set forth in section 101-1.
4. Applicability. The flood zone shall apply to all areas of special flood hazards, as shown on the adopted FEMA FIRM maps, within the jurisdiction of the county.
5. Flood insurance rate map adopted by reference. The areas of special flood hazard identified by the Federal Insurance Administration on its flood insurance rate map (FIRM), is adopted by reference and declared to be a part of the ordinance codified in this section.
6. Permit procedures. Application for a floodplain development permit shall be made to the floodplain administrator on forms furnished by the administrator or the administrator's designee prior to starting development activities. Specifically, the following information is required:
   1. Application stage.
      1. Plans in duplicate drawn to scale with elevations of the project area and the nature, location, and dimensions of existing and proposed structures, earthen fill placement, storage of materials or equipment and drainage facilities;
      2. Elevation in relation to the flood protection elevation, or highest adjacent grade, of the lowest floor level, including crawlspaces or basement, of all proposed structures;
      3. Elevation to which any nonresidential structure will be floodproofed;
      4. Design certification from a registered professional engineer or architect that any proposed nonresidential floodproofed structure will meet the floodproofing criteria in article V(F)(2), FEMA guidelines; and
      5. Description of the extent to which any watercourse will be altered or relocated as a result of a proposed development.
   2. Construction stage.
      1. For all new construction and substantial improvements, the permit holder shall provide to the floodplain administrator an as-built certification of the floor elevation or floodproofing level, using appropriate FEMA elevation or floodproofing certificate, immediately after the lowest floor or floodproofing is completed. When floodproofing is utilized for nonresidential structures, the certification shall be prepared by or under the direct supervision of a professional engineer or architect and certified by same.
      2. Certificate deficiencies identified by the floodplain administrator shall be corrected by the permit holder immediately and prior to work proceeding. Failure to submit certification or failure to make the corrections shall be cause for the floodplain administrator to issue a stop work order for the project.
   3. Technical review. If the community does not have the expertise to evaluate the technical data that is part of the application, the community may contract for an independent engineering review or require a review by FEMA through the letter of map revision process. The applicant will pay the costs of an independent technical review.
   4. Expiration of floodplain development permit. All floodplain development permits shall be conditional upon the commencement of work within 1 year. A floodplain development permit shall expire 1 year after issuance unless the permitted activity has been substantially begun and thereafter is pursued to completion.
7. Administrator appointed; duties. A designee of the county shall be appointed to administer and implement this zone by granting or denying permit applications in accordance with its provisions. Duties and responsibilities of the administrator:
   1. Review all floodplain development permit applications to ensure that the permit requirements of this section have been satisfied.
   2. Review proposed development to ensure that necessary permits have been received from governmental agencies from which approval is required by federal or state law, including section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 USC 1334; the Endangered Species Act of 1973, 16 USC 1531—1544; and state stream channel alteration permits. Idaho Code, title 42, ch. 38 (Idaho Code, § 42-3801 et seq.) requires that copies of such permits be provided and maintained on file.
   3. When base flood elevation data or floodway data are not available, then the floodplain administrator shall obtain, review and reasonably utilize any base flood elevation and floodway data available from a federal, state or other source in order to administer the provisions of this section.
   4. When base flood elevations or other current engineering data are not available, the floodplain administrator shall take into account the flood hazards, to the extent they are known, to determine whether a proposed building site will be reasonably safe from flooding.
   5. Obtain, verify and record the actual elevation in relation to the vertical datum on the effective FIRM, or highest adjacent grade, of the lowest floor level, including basement, of all new construction or substantially improved structures.
   6. Obtain, verify and record the actual elevation, in relation to the vertical datum on the effective FIRM to which any new or substantially improved structures have been floodproofed.
   7. When floodproofing is utilized for a structure, the floodplain administrator shall obtain certification of design criteria from a registered professional engineer or architect.
   8. Where interpretation is needed of the exact location of boundaries of the areas of special flood hazard including regulatory floodway (for example, where there appears to be a conflict between a mapped boundary and actual field conditions) the floodplain administrator shall make the interpretation. Any person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in this section.
   9. All records pertaining to the provisions of this section shall be maintained in the office of the city/county clerk or his designee and shall be open for public inspection.
8. General standards. In all areas of special flood hazards the following standards are required:
   1. Anchoring.
      1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.
      2. All manufactured homes must likewise be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors (reference FEMA's Manufactured Home Installation in Flood Hazard Areas Guidebook for additional techniques).
   2. Construction materials and methods.
      1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
      2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
      3. Electrical, heating, ventilation, plumbing and air conditioning equipment, and other service facilities shall be designed to be watertight and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
   3. Utilities.
      1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
      2. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters.
      3. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
   4. Subdivision standards.
      1. All subdivision proposals shall be consistent with the need to minimize flood damage.
      2. All subdivision preliminary plats/development plans shall include the mapped flood hazard zones from the effective FIRM.
      3. Base flood elevation data shall be generated and/or provided for subdivision proposals and all other proposed development, including manufactured home parks and subdivisions, greater than 50 lots or 5 acres, whichever is less.
      4. All subdivisions shall have public utilities and facilities such as sewer, gas, electric and water systems located and constructed to minimize flood damage.
      5. All subdivisions shall have adequate drainage provided to reduce exposure to flood hazards, and shall show that construction shall have a zero rise effect on the floodplain.
   5. Review of building permits. Where elevation data is not available either through the flood insurance study or from another authoritative source, applications for building permits shall be reviewed to ensure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs or past flooding, etc., where available. Failure to elevate at least 2 feet above grade in these zones may result in higher insurance rates.
9. Construction standards. In all areas of special flood hazard the following provisions are required:
   1. All construction in the area of special flood hazard shall provide proof of not causing any rise to the floodplain or increase of flooding to neighboring properties.
   2. New construction and substantial improvements of an existing structure shall be anchored to prevent flotation, collapse or lateral movement of the structure.
   3. New construction and substantial improvements of an existing structure shall be constructed with materials and utility equipment resistant to flood damage.
   4. New construction or substantial improvements of an existing structure shall be constructed by methods and practices that minimize flood damage.
   5. All new construction or substantial improvements of an existing structure that includes a fully enclosed area located below the lowest floor formed by the foundation and other exterior walls shall be designed to be an unfinished or flood resistant enclosure. The enclosure shall be designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater. Designs for complying with this requirement must be certified by a licensed professional engineer or architect or meet the following minimum criteria:
      1. Provide a minimum of 2 openings:
         1. With a total net area of not less than 1 square inch for every square foot of enclosed area subject to flooding;
         2. The bottom of all openings shall be no higher than 1 foot above the higher of the exterior or interior grade or floor immediately below the opening;
         3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwater in both directions without manual intervention.
      2. To comply with the lowest floor criteria of this section, the unfinished or flood-resistant enclosure shall only be used for parking of vehicles, limited storage of maintenance equipment used in connection with the premises, or entry to the elevated area.
      3. The interior portion of such enclosed area shall not be partitioned or finished into separate rooms.
   6. For crawlspace foundation types, construction must follow the guidelines in FEMA Technical Bulletin (TB) 11-01, crawlspace construction for structures located in special flood hazard areas: National Flood Insurance Program interim guidance, specifically:
      1. Belowgrade crawlspaces are prohibited at sites where the velocity of floodwaters exceed 5 feet per second.
      2. Interior grade of the crawlspace below the BFE must not be more than 2 feet below the lowest adjacent exterior grade (LAG).
      3. Height of the belowgrade crawlspace, measured from the lowest interior grade of the crawlspace to the bottom of the floor joist must not exceed 4 feet at any point.
      4. Contain an adequate drainage system that removes floodwaters from the interior area of the crawlspace.
      5. All heating and air conditioning equipment and components, all electrical, ventilation, plumbing and other facilities shall be designed and/or elevated to prevent water from entering or accumulating within the components during flooding.
      6. New and replacement water supply systems shall be designed to minimize or to eliminate infiltration of floodwaters into the system.
      7. New and replacement sanitary sewage systems shall be designed to minimize or to eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.
      8. On-site waste disposal systems shall be located and constructed to avoid functional impairment, or contamination from them, during flooding.
      9. Any alteration, repair, reconstruction or improvement to a structure that is not in compliance with the provisions of this chapter, shall be undertaken only if the nonconformity is minimal in order to meet health and safety standards.
      10. The top of all septic tanks and wellheads shall be elevated to at least 1 foot above BFE (base flood elevation).
10. Manufactured home standards. In all areas of special flood hazard where the flood protection elevation is established, the following standards for manufactured homes and recreational vehicles that are an allowed use under this chapter shall apply:
    1. Manufactured homes placed or substantially improved:
       1. On individual lots or parcels.
       2. In new or substantially improved manufactured home parks or subdivisions.
       3. In expansions to existing manufactured home parks or subdivisions, or on a site in an existing manufactured home park or subdivision where a manufactured home has incurred substantial damage as the result of a flood, must have the lowest floor, including basement, elevated to the flood protection elevation.
    2. Manufactured homes placed or substantially improved in an existing manufactured home park or subdivision may be elevated so that:
       1. The lowest floor of the manufactured home is elevated to the flood protection elevation, or 1 foot above the level of the base flood elevation, whichever is higher; or
       2. The manufactured home chassis is elevated and supported by reinforced piers (or other foundation elements of at least an equivalent strength) of no less than 36 inches above the highest adjacent grade.
    3. Manufactured homes shall be anchored to prevent flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This standard shall be in addition to, and consistent with, applicable state requirements.
    4. Manufactured homes placed on solid perimeter walls shall meet the flood vent requirements in article V(B)(4), FEMA guidelines.
11. Accessory structures. Relief from the elevation or dry floodproofing standards may be granted for an accessory structure containing no more than 120 square feet. Such a structure must meet the following standards:
    1. It shall not be used for human habitation;
    2. It shall be constructed of flood-resistant materials;
    3. It shall be constructed and placed on the lot to offer the minimum resistance to the flow of floodwaters;
    4. It shall be firmly anchored to prevent flotation;
    5. Services such as electrical and heating equipment shall be elevated or floodproofed to or above the flood protection elevation; and
    6. It shall meet the opening requirements of article V(B)(4), FEMA guidelines.
12. Recreational vehicle standards. In all areas of special flood hazard, recreational vehicles, that are an allowed use or structure under this chapter, must either:
    1. Be on the site for fewer than 180 consecutive days;
    2. Be fully licensed and ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect-type utilities and security devices, and have no permanently attached structures or addition; or
    3. Meet all the requirements for new construction, including the anchoring and elevation requirements.
13. Floodway standards. The following provisions shall apply in a floodway:
    1. A project in the regulatory floodway must undergo an encroachment review to determine its effect on flood flows. An encroachment analysis must include:
       1. Determination and documentation that the filling, grading or construction of a structure will not obstruct flood flows and will not cause an increase in flood heights upstream or adjacent to the project site;
       2. Determination and documentation that grading, excavation, channel improvements, bridge and culvert replacements that remove an obstruction, do not cause increases in downstream flood flows;
       3. Certification and documentation by a licensed professional engineer that the project will not result in a rise in flood heights; and
       4. The administrator may make the encroachment determination for minor projects.
    2. An encroachment in the floodway or floodplain that will cause an increase in the base flood elevation in excess of the allowable level must have a conditional letter of map revision granted by FEMA before it will be permitted.
14. Standards for zones with base flood elevations. In special flood hazard areas designated as A1—30, AE, AH, and/or A (with estimated BFE), the following provisions are required.
    1. New construction and substantial improvements. Where base flood elevation data are available, new construction or substantial improvement of any structure or manufactured home shall have the lowest floor, including basement, constructed at or above the community's flood protection elevation. If solid foundation perimeter walls are used to elevate a structure, openings sufficient to facilitate the unimpeded movement of floodwaters shall be provided in accordance with the construction standards in article V(B)(4), FEMA guidelines.
    2. Nonresidential construction. New construction or the substantial improvement of any nonresidential structure located in zones A1—30, AE, or AH must be floodproofed if the new construction or improvement is not elevated. The structure and attendant utility and sanitary facilities, must be designed to be watertight to the flood protection elevation or to 1 foot above the base flood elevation, whichever is higher, with walls substantially impermeable to the passage of water, and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A licensed professional engineer or architect must certify that the design and methods of construction are in accordance with accepted standards of practice for meeting these provisions, and shall provide this certification to the administrator.
    3. Where the floodway has not been determined, applicants of proposed projects that increase the base flood elevation more than 1 foot are required to obtain and submit to the floodplain administrator, a conditional letter of map revision (CLOMR) preconstruction.
    4. Post construction, the applicant must apply to FEMA for a letter of map revision for changes to the flood hazard map proposed in the CLOMR.
    5. In AH zones, drainage paths shall be provided to guide floodwater around and away from proposed and existing structures.
15. Standards for zones without base flood elevations and/or floodway A zones. These standards apply in special flood hazard areas where streams exist but no base flood elevation data have been provided (A zones), or where base flood data have been provided but a floodway has not been delineated.
    1. When base flood elevation or floodway data have not been identified by FEMA in a flood insurance study and/or flood insurance rate maps, then the floodplain administrator shall obtain, review and reasonably utilize scientific or historic base flood elevation and floodway data available from a federal, state or other source, in order to administer this section. If data is not available from any source, only then subsections (o)(2) and (3) of this section shall apply. Where the floodplain administrator has obtained base flood elevation data, applicants of proposed projects that increase the base flood elevation more than 1 foot shall obtain a conditional letter of map revision preconstruction and a letter of map revision post construction.
    2. No encroachments, including structures or fill, shall be located within an area equal to the width of the stream or 50 feet, whichever is greater, measured from the ordinary high-water mark, unless certification by a licensed professional engineer documents that the encroachment will not result in any increase in flood levels during the base flood.
    3. In special flood hazard areas without base flood elevation data, new construction and substantial improvements of existing structures shall have the lowest floor of the lowest enclosed area (including basement or crawlspace) elevated no less than 2 feet above the highest adjacent grade at the building site. Openings sufficient to facilitate the unimpeded movement of floodwaters shall be provided in accordance with the construction standards in article V(B)(4), FEMA guidelines.
16. Standards for areas of shallow flooding (AO zones). Shallow flooding areas designated AO zones, are areas of special flood hazard that have base flood depths of 1 to 3 feet, with no clearly defined channel. The following provisions apply:
    1. All new construction and substantial improvements of residential and nonresidential structures shall have the lowest floor, including basement, elevated above the adjacent grade at least as high as the flood depth number specified in feet on the flood insurance rate map (FIRM). If no flood depth number is specified, the lowest floor, including basement, shall be elevated at least 2 feet above the highest adjacent grade. Openings sufficient to facilitate the unimpeded movement of floodwaters shall be provided in accordance with the construction standards in article V(B)(4), FEMA guidelines.
    2. New construction or the substantial improvement of a nonresidential structure may be floodproofed in lieu of elevation. The structure and attendant utility and sanitary facilities must be designed to be watertight to the specified base flood level or at least 2 feet above highest adjacent grade, with walls substantially impermeable to the passage of water, and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A registered professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting these provisions, and shall provide certification to the floodplain administrator.
    3. Drainage paths shall be provided to guide floodwater around and away from all proposed and existing structures.
17. Alteration of a watercourse. A watercourse is considered altered when any change occurs within its banks.
    1. The bank's full flood-carrying capacity of the altered or relocated portion of the watercourse shall not be diminished. Prior to issuance of a floodplain development permit, the applicant must submit a description of the extent to which any watercourse will be altered or relocated as a result of the proposed development and submit certification by a registered professional engineer that the bank's full flood-carrying capacity of the watercourse will not be diminished.
    2. Adjacent communities, the U.S. Army Corps of Engineers and the state department of water resources stream channel alteration program must be notified prior to any alteration or relocation of a watercourse. Evidence of notification must be submitted to the floodplain administrator and to the Federal Emergency Management Agency.
    3. The applicant shall be responsible for providing the necessary maintenance for the altered or relocated portion of the watercourse so that the flood-carrying capacity will not be diminished.
    4. The applicant shall meet the requirements to submit technical data in subsection (r) of this section when an alteration of a watercourse results in the relocation or elimination of the special flood hazard area, including the placement of culverts.
18. Requirement to submit new technical data.
    1. For all development proposals that impact floodway delineations or base flood elevations, the community shall ensure that technical data reflecting such changes be submitted to FEMA within 6 months of the date such information becomes available. These development proposals include:
       1. Floodway encroachments that increase or decrease base flood elevations or alter floodway boundaries;
       2. Fill sites to be used for the placement of proposed structures where the applicant desires to remove the site from the special flood hazard area;
       3. Alteration of watercourses that result in a relocation or elimination of the special flood hazard area, including the placement of culverts; and
       4. Subdivision or large-scale development proposals requiring establishment of base flood elevations according to article V(A)(3), FEMA guidelines.
    2. It is the responsibility of the applicant to have technical data prepared in a format required for a conditional letter of map revision or letter of map revision and submitted to FEMA. Submittal and processing fees for these map revisions shall be the responsibility of the applicant.
19. Floodplain compliance disclaimer. The county, in issuing a building permit for construction within this zone, makes no representation to the applicant of the county's compliance with federal and state laws because a report entitled "The Flood Insurance Study for Madison County," with accompanying flood insurance maps, has not been completed and submitted to the county by the National Flood Insurance Program; therefore, the county makes no representation pertaining to the issuance of permits within the floodplain or the ability of the applicant to obtain federally sponsored financing for construction or sale of a building or that the applicant will be able to obtain national flood insurance.
20. Building adjacent rivers. A minimum of a 200-foot setback measured from 5 feet vertically above the high-water mark of the flow created by any impounded waters of any river shall be required of all buildings adjacent to all natural waterways in the county.
21. Floodplain construction. The foregoing provisions of this section notwithstanding, all construction within the floodplain may be subjected to conditional use approval, dependent upon the commission's approval.
22. Appeals. All appeals shall follow the appeals process as set forth in chapter 101, article VI.

(Prior Code, title 10, § 4.14)