A. Floodway Subdistrict Use Regulations: Because of the possibility of flooding and changeable characteristics of streams in the County, development in the regulatory floodway is highly restricted. All development within the floodway shall comply with the following:
1. Demonstrate that the proposed encroachment will not result in any increase in base flood elevation, based on hydrologic and hydraulic analyses performed in accordance with standard engineering practice.
2. Compliance with all specific use regulations outlined in subsection E of this section.
3. Written notification with details regarding description of work, location, and a proposed construction activities schedule shall be submitted to the Blaine County Land Use Office prior to the start of work.
a. Permitted uses:
(1) Maintenance or repair of pre-existing agricultural uses including, but not limited to, pipes, headgates, diversion structures, pumps, fences and weirs, provided that no agricultural buildings are involved. New or expansion of pre- existing agricultural uses are subject to the stream alteration permit requirements including no-rise certification.
(2) Activities operating in accordance with a County-approved stream alteration permit.
b. Prohibited uses:
(1) Any encroachment into the floodway, including fill, new construction, substantial improvements or modifications, stream alterations or other development that would cause any increase of the base flood elevation, thus jeopardizing the County's eligibility for participation in the NFIP.
(2) Any development whereby potential adverse impacts cannot be mitigated through the stream alteration permit process.
(3) Any use located within a wellhead protection area that may adversely impact a potable water source.
B. Floodplain Subdistrict Use Regulations: Because of hazard to individual and public health, safety, and welfare, uses in the Floodplain Subdistrict are restricted or designated for individual consideration under the categorical exclusion or conditional use permit process. All uses within the floodplain shall comply with the following:
1. Demonstrate that the proposed development will result in no adverse impacts to adjacent properties, as defined.
2. Compliance with all specific use regulations outlined in subsection E of this section.
3. Written notification with details regarding description of work, location, and a proposed construction activities schedule shall be submitted to the Blaine County Land Use Office prior to the start of work.
a. Permitted Uses:
(1) Agricultural, recreational, and residential accessory uses (nonstructural) which are designed to withstand flooding and will not increase the risk of flood losses on other land, to the public nor to the environment; inundation or flood damage to said permitted uses shall not be considered extraordinary circumstances. This includes the temporary installation of flood control barriers, ninety (90) days or less, when located no more than ten feet (10') from a structure.
(2) Sub-grade utilities such as fiber optics, pipelines, power or gas lines provided that they do not involve the placement of fill or that requirements for balanced cut and fill are met.
(3) At-grade sidewalks and pedestrian or equestrian pathways or trails.
b. Categorically Excluded Uses: A conditional use permit shall not be required provided the landowner or agent, before commencing any work, first obtains a written decision from the Administrator, in consultation with the County Engineer, Floodplain Manager, or his/her designated representative, that the development falls within and meets one of the following categorical exclusions and all of the requirements in subsection 9-17-6-E are satisfied, as applicable.
(1) Single-family residences and structures and uses accessory thereto, when located fully within an approved platted building envelope shown on a recorded subdivision plat;
(2) Fences, provided they will not divert the passage of floodwaters;
(3) Retaining walls, bulkheads, driveways, patios, decks, porches, pools, spas, and landscaping berms and other non-structural residential uses;
(4) Docks, piers, boat ramps, and marinas;
(5) Farm and garden buildings, and the storage of boats, campers and travel trailers by residents;
(6) Wireless communication facilities, refer to chapter 3 of this title;
(7) Above grade utilities;
(8) Bridges and culverts within or spanning Class 2, 3 or 4 streams; and
(9) New structures for the authorized delivery of water.
c. Conditional Uses: For any proposed conditional use, the applicant shall demonstrate that adverse impacts are mitigated through the conditional use permit procedure:
(1) Commercial or public works sand and gravel extractions;
(2) Gravel or shale pits, or asphalt plants;
(3) Bridges and culverts within or spanning Class 1 streams; and
(4) Residential structures located outside platted building envelopes;
(5) Other projects as the Administrator deems necessary due to adverse impacts or local public interest conflicts.
d. Prohibited Uses:
(1) Subdivision lots or lands for residential development within the floodplain that do not include a buildable site;
(2) Any use, activity, or structure that could cause flood damage to other property or environmental damage, including but not limited to removal of live or dead vegetation;
(3) Any use or structure that could cause the reduction of flow capacity or blockage of a side or overflow channel; or
(4) Any use located within a wellhead protection area that may adversely impact a potable water source.
C. Dimensional Standards: Any buildable lot within a Floodplain Overlay District shall use the setbacks required in the Riparian Setback District for the class of stream involved. More restrictive setbacks may be imposed through the conditional use permit or subdivision review process.
D. Development Density: The base development density in the Floodplain Overlay District shall be the base density in the adjacent zoning district or one unit per five (5) acres, whichever is less dense.
Floodway land may be included in determining development density. For a parcel of land which straddles the Floodplain Overlay District and a residential district, individual lots may be drawn which include portions of the Floodplain Overlay District. However, each lot shall include land outside of the riparian setback and outside of the Floodplain Overlay District.
E. Specific Use Requirements: The following provisions apply to all uses within the Floodway and Floodplain Subdistricts. The burden of proof always rests with the applicant:
1. Local Public Interests: The proposed application (use) does not conflict with the local public interest, i.e., the affairs of the people in the area directly affected by the proposed use. This includes, but is not limited to, property values, fish and wildlife habitat, aquatic life, recreation, water quality, potable water sources or an impact upon a locally important factor.
2. Changes To The Flood Insurance Rate Map: Any boundary or base flood elevation established by a registered professional engineer in the State that is in conflict with the effective flood insurance study (FIS) must be submitted to and approved by FEMA through a revised FIRM, or through a letter of map change (LOMC) issued by FEMA. Such amendments or revisions to the effective FIRMs authorized by FEMA shall be considered amendments or revisions to the maps adopted hereinabove and may be used as the best available information.
3. Riparian Habitat: Replacement of native riparian habitat, including vegetation, shall be required for all disturbed areas within the required setbacks.
4. Location: Development and building sites or envelopes shall be located outside of the Floodplain Overlay District, where such areas are available, unless such a location would result in greater adverse impacts to wetland, riparian, or other risk areas.
5. Anchoring: All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
6. Requirements For Structures Partially In The Floodplain Overlay District: When a structure is partially located in the Floodway or Floodplain Subdistricts, the entire structure shall meet the requirements for new construction and substantial improvements.
7. Additional Permits: Categorical exclusions, conditional use permits and building permits shall be reviewed to determine that all necessary permits have been obtained from those Federal, State or local governmental agencies from which prior approval is required.
8. Construction Materials And Methods: All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage, using methods and practices that minimize flood damage. All new and replacement electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities shall be elevated to BFE, so as to prevent water from entering or accumulating within the components during conditions of flooding. These include, but are not limited to, HVAC equipment, water softener units, bath/kitchen fixtures, ductwork, electric/gas meter panels/boxes, utility/cable boxes, hot water heaters, and electric outlets/switches.
9. Basements: Basements are prohibited within the Floodplain and Floodway Subdistricts.
10. Utilities: New and replacement water disposal, sanitary sewage, and water supply facilities shall be designed to minimize or prevent the infiltration of floodwaters to avoid impairment to them or contamination from them during flooding. A permit shall be received from the South Central Public Health District who shall determine the specific system to be used.
11. Residential Construction:
a. New construction and substantial improvement of any residential structure shall have the lowest floor elevated to or above flood protection elevation.
b. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited or shall be used solely for parking of vehicles, building access or storage and be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
(1) A minimum of two (2) openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided. Credit is only provided for openings below BFE;
(2) The bottom of all openings shall be no higher than one foot (1') above grade;
(3) Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(4) Fully enclosed areas below the lowest floor shall only be used for parking, building access or storage.
(5) Flood-resistant material shall be used at least to the flood protection elevation.
(6) For crawl space foundation types, construction must follow the guidelines as set forth in this chapter or FEMA TB (technical bulletin) 11-01, crawl space construction for structures located in special flood hazard areas: national flood insurance program interim guidance whichever is more restrictive, specifically:
(A) Below grade crawl spaces are prohibited at sites where the velocity of floodwaters exceeds five feet (5') per second;
(B) Interior grade of the crawl space below the BFE must not be more than two feet (2') below the lowest adjacent exterior grade (LAG);
(C) Height of the below grade crawl space, measured from the lowest interior grade of the crawl space to the bottom of the floor joist must not exceed four feet (4') at any point;
(D) Contain an adequate drainage system that removes floodwaters from the interior area of the crawl space.
12. Nonresidential Construction: New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, or top side of slab on grade, elevated to the level of the base flood elevation; or, together with attendant utility and sanitary facilities, shall:
a. Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
c. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection for the structural design, specifications and plans. Such certifications shall be provided to the Administrator.
d. Nonresidential structures that are elevated, and not floodproofed, must meet the same standards for space below the lowest floor as described in "residential construction" of this subsection E.
e. Applicants floodproofing nonresidential buildings are hereby notified that flood insurance premiums will be based on rates that are one foot (1') below the floodproofed level (e.g., a building constructed to the base flood level will be rated as 1 foot below that level).
13. Appurtenant Structures (Detached Garages And Storage Structures): Appurtenant structures used solely for parking of vehicles or storage may either be elevated or meet the design requirements in subsection E11b of this section.
14. Manufactured Homes: All manufactured homes to be placed or substantially improved shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at least elevated to the flood protection elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of this subsection E.
15. Recreational Vehicles: In the Floodplain Overlay District, recreational vehicles, must either:
a. Be stored on the site for fewer than one hundred eighty (180) consecutive days and are subject to removal during base flood conditions;
b. 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 additions; or
c. The recreational vehicle must meet all the requirements for "new construction", including the anchoring and elevation requirements.
16. Subdivision Proposals (Refer Also To Title 10, "Subdivision Regulations", Of This Code):
a. All subdivision proposals shall be consistent with the need to minimize flood damage and shall meet the requirements of this chapter;
b. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage;
c. All subdivision proposals shall provide adequate drainage to minimize potential flood damage; and
d. Where base flood elevation data has not been provided or is not available, it shall be generated for subdivision proposals and other proposed developments which contain at least fifty (50) lots or five (5) acres (whichever is less). The subdivision applicant shall submit the determined base flood elevation data to FEMA prior to preliminary plat approval and obtain approval from FEMA prior to final plat approval.
17. Tanks: When gas and liquid storage tanks are to be placed in the Floodplain Subdistrict, the following criteria shall be met:
a. Underground tanks shall be anchored to prevent flotation, collapse, or lateral movement resulting from hydrodynamic and hydrostatic loads during the base flood, including the effects of buoyancy.
b. Above-ground tanks shall be anchored to prevent flotation, collapse, or lateral movement during conditions of the base flood or elevated to the FPE.
c. Tank inlets, fill openings, outlets and vents shall be:
(1) At or above the FPE or fitted with covers designed to prevent the inflow of floodwater or outflow of the contents of the tanks during conditions of the base flood; and
(2) Anchored to prevent lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the base flood.
18. Standards For Shallow Flooding Areas (AO Zones): Shallow flooding areas appear on FIRMs as AO Zones with depth designations. The base flood depths in these zones range from one foot to three feet (1' - 3') where a clearly defined channel does not exist or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In these areas, the following provisions apply:
a. New construction and substantial improvements of residential structures within AO Zones shall have the lowest floor elevated above the highest adjacent grade of the building site, to or above the depth number specified on the FIRM (at least 2 feet if no depth number is specified and no less than 2 feet).
b. New construction and substantial improvements of nonresidential structures within AO Zones shall either:
(1) Have the lowest floor elevated above the highest adjacent grade of the building site, to or above the depth number specified on the FIRM (at least 2 feet if no depth number is specified and no less than 2 feet); or
(2) Together with attendant utility and sanitary facilities, be completely floodproofed to or above that level so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect.
19. AH/AO Zone Drainage: Adequate drainage course shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.
20. No Base Flood Elevation Data Available: The Administrator shall obtain, review and reasonably utilize any Federal, State or local source to determine a BFE. In areas without base flood elevation data, the following provisions apply:
a. New construction, including placement of manufactured homes, and substantial improvements of existing structures shall have the lowest floor elevated no less than two feet (2') above the highest adjacent grade at the building site to assure that the structure is reasonably safe from flooding.
b. Openings sufficient to facilitate the movement of floodwaters in accordance with subsection E11b of this section construction standards are required for enclosed areas used solely for parking, access or storage below the required floor elevation.
21. Certification Requirements: All elevations as specified hereunder shall be certified on a FEMA Elevation Certificate by a licensed surveyor or engineer secured by the applicant, and made part of permit records.
a. As-built elevation of lowest floor including basement, of all new or substantially improved structures;
b. As-built floodproofed elevation of all new or substantially improved nonresidential structures;
c. As-graded elevation of lowest crawl space grade, as applicable.
d. Floodproofing measures shall be designed consistent with the flood protection elevation for the particular area, flood velocities, durations, rate of rise, hydrostatic and hydrodynamic forces, and other factors associated with the regulatory flood. The applicant shall submit a plan or document certified by a registered professional engineer that the floodproofing measures are consistent with the regulatory flood protection elevation and associated flood factors for the particular area. Floodproofing plans shall include the operation, inspection and maintenance of such measures.
22. Floodway Not Determined: Where the floodway has not been determined, no new construction, substantial improvements, or other development (including fill) shall be permitted in Zones AE on the effective FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot (1') at any point within the community. Applicants of proposed projects that increase the base flood elevation more than one foot (1') are required to obtain and submit to the Floodplain Administrator, a conditional letter of map revision (CLOMR) preconstruction.
F. Variance: When applicable, an applicant may seek an exception from the standards and requirements of this section and 9-17-10(A)2 by means of a variance as provided in Section 12 of this chapter. (Ord. 77-5, 3-28-1977, eff. 4-7-1977; amd. Ord. 79-4, 9-11-1979; Ord. 88-4, 9-13-1988; Ord 90-4, 6-11-1990; Ord. 91-9, 7-22-1991; Ord. 92-5, 9-14-1992; Ord. 92-7, 9-28-1992; Ord. 96-3, 4-8-1996; Ord. 97-1, 7-22-1997; Ord. 98-5, 6-8-1998; Ord 2000-3, 3-20-2000; Ord. 2001-10, 10-1-2001; Ord. 2006-13, 10-26-2006; Ord 2006-18, 11-2-2006; Ord. 2010-08, 11-16-2010; Ord. 2010-13, 1-18-2011; Ord.2011-01, 1-18-2011; Ord. 2014-03, 8-19-2014; Ord. 2019-02, 1-8-2019; Ord. 2021-12, 7-20-2021; Ord. 2023-01, 1-3-2023)