Ordinance Text
8-2-28: FLOOD HAZARD (FH) OVERLAY DISTRICT:
A. Purpose: The purpose of the Flood Hazard Overlay (FH) District is to promote public health, safety, and general welfare and to minimize public and private losses due to potential flooding. The provisions are designed to:
1. Protect human life, health, and property;
2. Minimize damage to public facilities and utilities such as water purification and sewage treatment plants, water, and gas mains, electric, telephone and sewer lines, streets, and bridges located in floodplains;
3. Provide for the sound use and development in flood prone areas;
4. Minimize expenditure of public money for costly flood control projects;
5. Minimize the need for rescue and emergency services associated with flooding, generally undertaken at the expense of the general public;
6. Minimize prolonged business interruptions;
7. Ensure potential buyers are notified the property is in an area of special flood hazard; and
8. Ensure those who occupy the areas of special flood hazard assume responsibility for their actions.
B. Warning And Disclaimer: The degree of flood protection required by this Section is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur. Flood heights may be increased due to artificial or natural causes. This Section does not imply that property outside the identified Special Flood Hazard Areas will be free from flooding or flood damages, or that uses permitted within the identified Special Flood Hazard Areas will be free from flooding or flood damages. This Section shall not create liability on the part of Ada County, any officer or employee thereof, or the federal insurance and mitigation administration, for any flood damages that result from adherence to this Section, or any administrative decision lawfully made hereunder. If any Section, provision, or portion of this ordinance is adjudged unconstitutional or invalid by a court, the remainder of the ordinance shall not be affected.
C. Authority: This Section is adopted pursuant to Idaho Code Section 46-1001, et seq., which authorizes local governments to adopt floodplain management ordinances that identify floodplains and minimum floodplain development standards to minimize flood hazards and protect human life, health, and property.
D. Applicability: These regulations shall apply to "development" as defined in this Section, excluding additions to existing buildings when the addition is not classified as a "substantial improvement" per this Section, within all Special Flood Hazard Areas identified by one or more of the following:
1. The federal insurance and mitigation administration in a scientific and engineering report entitled "The Flood Insurance Study (FIS) For Ada County, Idaho," revised June 19, 2020, and all subsequent amendments and revisions, and the accompanying Flood Insurance Rate Maps (FIRM) and Digital Flood Insurance Rate Maps (DFIRMS), and all subsequent amendments and revisions to such maps, are hereby adopted by reference and serve as the basis for establishing flood hazard areas. Maps and studies that establish flood hazard areas are on file at the Ada County Development Services Department.
2. Foothill or other hillside tributary floodplains as herein defined.
E. Administration:
1. Floodplain Administrator Responsibilities: The Director, or their designee, hereinafter referred to as the "Floodplain Administrator," is hereby appointed to administer and implement the provisions of this Section and shall have the following responsibilities in all Special Flood Hazard Areas:
a. Review all floodplain development applications and issue permits for all proposed development within Special Flood Hazard Areas to determine whether proposed building sites comply with the requirements for building in a Special Flood Hazard Area.
b. Review all proposed development within Special Flood Hazard Areas to assure that all necessary local, state, and federal permits have been received, including Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 USC Section 1334.
c. Notify adjacent communities and the Idaho Department of Water Resources State Coordinator for the National Flood Insurance Program (NFIP) prior to any alteration or relocation of a watercourse. (This is the LOMC procedure).
d. Confirm stream channel or water course alteration meets the current Federal Emergency Management Agency (FEMA) NFIP regulations.
e. Prevent unpermitted encroachments into the floodway.
f. Obtain and maintain actual elevation (in relation to mean sea level) of the lowest floor (including basement) and all attendant utilities of all new and substantially improved structures.
g. Obtain and maintain actual elevation (in relation to mean sea level) to which all new and substantially improved structures and utilities have been floodproofed.
h. Review plans to verify public utilities are constructed to minimize flood damage.
i. When floodproofing is utilized for a particular structure, obtain, and maintain Floodproofing Certifications on the latest FEMA approved forms.
j. Where interpretation is needed as to the exact location of boundaries of the Special Flood Hazard Areas, and floodways (for example, where there appears to be a conflict between a mapped boundary and actual field conditions), make the necessary interpretation in conjunction with entity making conflicting decision. The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in this Section.
k. When Base Flood Elevation (BFE) data has not been provided, obtain, review, and reasonably utilize any BFE data, along with floodway data available from a federal, state, or other source.
l. When Base Flood Elevation (BFE) data is provided but no floodway data has been provided, require that no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A (or A1-30) and AE on Ada County's 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 (1) foot at any point within Ada County. (This is a Hydraulic & Hydrology Analysis.)
m. When the lowest floor and the lowest adjacent grade of a structure or the lowest ground elevation of a parcel in a Special Flood Hazard Area (SFHA) is above the Base Flood Elevation (BFE), advise the property owner of the option to apply for a Letter of Map Amendment (LOMA) from FEMA. Maintain a copy of the LOMA issued by FEMA in the floodplain development permit file.
n. Permanently maintain all records that pertain to the administration of this Section.
o. Make on-site inspections of work in progress. As the work pursuant to a floodplain development permit progresses, the floodplain administrator shall make as many inspections of the work as may be necessary to ensure that the work is being done according to the provisions of this Section and the terms of the permit. In exercising this power of inspection of work related to a permit, the floodplain administrator has a right, upon presentation of proper credentials, to enter on any premises within Ada County at any reasonable hour for the purposes of inspection or other enforcement action.
p. Issue stop-work orders as required. Whenever a building or part thereof is being constructed, reconstructed, altered, or repaired in violation of this Section, the floodplain administrator may order the work to be immediately stopped. The stop-work order shall be in writing and directed to the person doing or in charge of the work. The stop-work order shall state the specific work to be stopped, the specific reason(s) for the stoppage, and the condition(s) under which the work may be resumed.
q. Revoke floodplain development permits as required. The Floodplain Administrator may revoke and require the return of the floodplain development permit by notifying the permit holder in writing stating the reason(s) for the revocation. Permits shall be revoked for any substantial departure from the approved application, plans, and specifications; for refusal or failure to comply with the requirements of state or local laws; or for false statements or misrepresentations made in securing the permit. Any floodplain development permit mistakenly issued in violation of an applicable state or local law may also be revoked.
r. Make periodic inspections throughout the Special Flood Hazard Areas within Ada County.
s. Prohibit activities that violate the regulations of this Section.
t. Review, provide input, and make recommendations for variance requests.
u. Maintain a current map repository to include, but not limited to, the FIS Report, FIRM and other official flood maps, and studies including any revisions thereto including Letters of Map Change, issued by FEMA. Notify the NFIP State Coordinator and FEMA of your community's mapping needs.
v. Coordinate revisions to FIS reports and FIRMs, including Letters of Map Revision Based on Fill (LOMR-Fs) and Letters of Map Revision (LOMRs).
2. Interpretation: All of the regulations of this Section shall be considered as minimum requirements and shall be considered liberally construed in favor of the governing body and shall not be deemed to limit or repeal any other powers granted under state statutes.
F. Definitions: For the purposes of this Section, the terms, as herein defined, shall be used in the administration of this Section:
A ZONE: A Special Flood Hazard Area delineated on the flood insurance rate map (FIRM) that is subject to inundation by the one percent (1%) annual chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no base flood elevations or flood depths are shown.
AE ZONE: A Special Flood Hazard Area delineated on the flood insurance rate map (FIRM) that is subject to inundation by the one percent (1%) annual chance flood event determined by detailed methods. Base flood elevations are shown.
AREA OF SHALLOW FLOODING: An area within the flood fringe shown on the flood insurance rate map (FIRM) as an AO or an AH zone; and where the base flood depths range from one to three feet (3'), a clearly defined channel does not exist, the path of flooding is unpredictable and indeterminate, and velocity flow may be evident.
BASE FLOOD: The flood having a one percent (1%) chance of being equaled or exceeded each year. Also known as the "regulatory flood."
BASE FLOOD ELEVATION (BFE): A determination by the Federal Insurance Administrator of the water surface elevations of the base flood, that is, the flood level that has a one percent or greater chance of occurrence in any given year.
When the BFE has not been provided in a Special Flood Hazard Area, it may be obtained from engineering studies available from a federal, state, or other source using FEMA-approved engineering methodologies. This elevation, when combined with the Freeboard, establishes the Flood Protection Elevation.
BASEMENT: Any area of a structure having its floor subgrade (below ground level) on all sides, including a crawl space.
CHECK DAM: A structure erected perpendicular to the direction of flow of floodwaters in a foothill or other hillside tributary floodplain, and which does not exceed ten feet (10') in height or fifty (50) acre-feet of storage capacity and is constructed for the purpose of reducing the velocity of floodwaters or reducing flood flows downstream or both. For the purposes of this Section, energy dissipating devices shall be considered check dams.
CLEANING: Mowing, cutting, or burning of weeds, trees, and other nuisance growth, including algae growth, application of pesticides as permitted, removal of beaver dams, and removal of trash or other debris whether floating, lodged or otherwise obstructing the conveyance of water flow through channels and works.
CRITICAL FACILITIES: Facilities that are vital to flood response activities or critical to the health and safety of the public before, during, and after a flood, such as a hospital, emergency operations center, electric substation, police station, fire station, nursing home, school, vehicle and equipment storage facility, or shelter; and facilities that, if flooded, would make the flood problem and its impacts much worse, such as a hazardous materials facility, power generation facility, water utility, or wastewater treatment plant.
DEVELOPMENT: Any man-made change to improved or unimproved property, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations, or storage of equipment or materials.
DEVELOPMENT ACTIVITY: Any activity defined as Development which will necessitate a Floodplain Permit. This includes any man-made change to improved or unimproved property including, but not limited to, the construction of buildings, structures or accessory structures, or the construction of additions or substantial improvements to buildings, structures or accessory structures; the placement of mobile homes; filling, mining, dredging, grading, paving, excavation or drilling operations; storage of equipment and materials; and the deposition or extraction of materials; specifically including the construction of dikes, berms and levees.
DIGITAL FLOOD INSURANCE RATE MAP (DFIRM): A digital representation of a flood insurance rate map (FIRM) within an electronic mapping application depicting both the Special Flood Hazard Areas and the risk premium zones applicable within Ada County.
DREDGING: The removal of sediment from the bottom of streams creeks, irrigation and drainage channels and works.
ELEVATION CERTIFICATE: The Elevation Certificate is an important administrative tool of the NFIP. It is used to determine the proper flood insurance premium rate; it is used to document elevation information; and it may be used to support a request for a Letter of Map Amendment (LOMA), or Letter of Map Revision based on fill (LOMR-F).
FEMA REGULATORY FLOODWAY BOUNDARY: The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.
FLOOD ELEVATION STUDY (FES): An examination, evaluation and determination of flood hazards, flood profiles, floodway boundaries and water surface elevation of the base flood.
FLOOD FRINGE: The area between the floodway and the one hundred (100) year floodplain boundary, including the A zones where no floodway is identified (see Figure 8-2-28-1 Special Flood Hazard Area Diagram below).
FLOOD INSURANCE RATE MAP (FIRM): The official map of Ada County, on which the Federal Insurance Administrator has delineated both the Special Flood Hazard Areas and the risk premium zones applicable to Ada County. A FIRM that has been made available digitally is called a Digital Flood Insurance Rate Map (DFIRM).
FLOOD INSURANCE STUDY (FIS): An examination, evaluation, and determination of flood hazards and, if appropriate, corresponding water surface elevations; or an examination, evaluation, and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards.
FLOOD OR FLOODING:
A. A general and temporary condition of partial or complete inundation of normally dry land areas from:
1. The overflow of inland or tidal waters.
2. The unusual and rapid accumulation or runoff of surface waters from any source.
3. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in paragraph A2 of this definition and are akin to a river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current.
B. The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in paragraph A1 of this definition.
FLOOD PROTECTION ELEVATION (FPE): The Base Flood Elevation plus the Freeboard. In "Special Flood Hazard Areas" where Base Flood Elevations (BFEs) have been determined, this elevation shall be the BFE plus two feet (2') of freeboard.
FLOODPLAIN ADMINISTRATOR : The individual appointed to administer and enforce the floodplain management regulations.
FLOODPLAIN MANAGEMENT: The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to emergency preparedness plans, flood control works, and floodplain management regulations.
FLOODPLAIN MANAGEMENT REGULATIONS: Zoning regulations, subdivision regulations, building codes, health regulations, special purpose regulations (such as flood plain regulations, grading regulations, and erosion control regulations), and other applications of police power. The term describes such federal, state, or local regulations, in any combination thereof, which provide standards for the purpose of flood damage prevention and reduction.
FLOODPROOFING: Any combination of structural and non-structural additions, changes, or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents.
FLOODPLAIN AND BANK RESTORATION: The reestablishment of the structure and function of ecosystems and floodplains to return the ecosystem as closely as possible to its natural conditions and functions prior to being developed or impacted by a natural event.
FLOODPROOFING CERTIFICATE: A FEMA form used to certify a floodproofing design for a nonresidential structure that is being floodproofed as an alternative to elevating the structure to or above the base flood elevation.
FLOODWAY: See FEMA Regulatory Floodway Boundary.
FOOTHILL OR HILLSIDE TRIBUTARY FLOODPLAIN: A watercourse or drainageway located in the foothills or other hillside tributary that collects and carries water draining from an area of greater than ten (10) acres in size.
FREEBOARD: A factor of safety usually expressed in feet above a flood level for the purposes of floodplain management. Freeboard tends to compensate for the many unknown factors that could contribute to flood heights greater than the height calculated for a selected size flood and floodway conditions, such as wave action, obstructed bridge openings, debris and ice jams, and the hydrologic effects of urbanization in a watershed. The Base Flood Elevation (BFE) plus the freeboard establishes the Flood Protection Elevation (FPE). Freeboard shall be two feet (2').
FUNCTIONALLY DEPENDENT USE: A facility that cannot be used for its intended purpose unless it is located or carried out in close proximity to water, such as a docking or port facility necessary for the loading and unloading of cargo or passengers, shipbuilding, or ship repair facilities. The term does not include long-term storage, manufacture, sales, or service facilities.
HIGHEST ADJACENT GRADE: The highest natural elevation of the ground surface prior to construction, adjacent to the proposed walls of a structure. Refer to the FEMA Elevation Certificate for HAG related to building elevation information.
HISTORIC STRUCTURE: A structure that is:
A. Listed individually in the National Register of Historic Places (a listing maintained by the U.S. Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
B. Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or to a district preliminarily determined by the Secretary to qualify as a registered historic district;
C. Individually listed on a state inventory of historic places and determined as eligible by states with historic preservation programs which have been approved by the Secretary of the Interior; or
D. Individually listed on a local inventory of historic places and determined as eligible by communities with historic preservation programs that have been certified either:
1. By an approved state program as determined by the Secretary of the Interior; or
2. Directly by the Secretary of the Interior in states without approved programs.
IRRIGATION OR DRAINAGE CHANNEL: A man-made or natural channel used to convey or deliver water for irrigation, drainage, or other uses, by irrigation districts, canal companies, lateral associations, drainage districts, or other water delivery entities. Irrigation and drainage channels include man-made canals, ditches, laterals, culverts, flumes, tiled drains, pipes, storage reservoirs, and natural channels (including reservoirs on natural channels), used to convey storage or other sources of water owned or controlled by an irrigation or drainage entity.
IRRIGATION AND DRAINAGE WORKS: Man-made structures used to divert, regulate, and measure water from natural channels (streams, rivers, lakes, and springs) and in man-made irrigation and drainage channels. Irrigation and drainage work include diversions or regulation structures, including but not limited to control gates or head gates, check dams or diversion dams, culverts, measuring devices and their housing (including stilling wells and staff gages), flumes, siphons, pumps, pipes, protective structures, energy dissipaters, fish passage structures, and trash screens or trash racks.
LETTER OF MAP CHANGE (LOMC): A general term used to refer to the several types of revisions and amendments to FIRMs that can be accomplished by letter. They include Letter of Map Amendment (LOMA), Letter of Map Revision (LOMR), Letter of Map Revision based on Fill (LOMR-F), and Conditional Letters of Map Revision (CLOMR).
LETTER OF MAP AMENDMENT (LOMA): An official amendment, by letter, to an effective National Flood Insurance Program (NFIP) map. A LOMA establishes a property's or structure's location in relation to the Special Flood Hazard Area (SFHA). LOMAs are usually issued because a property or structure has been inadvertently mapped as being in the floodplain but is actually on natural high ground above the base flood elevation.
LETTER OF MAP REVISION (LOMR): FEMA's modification to an effective Flood Insurance Rate Map (FIRM) or a Flood Boundary and Floodway Map (FBFM) or both. LOMRs are generally based on the implementation of physical measures that affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective Base Flood Elevations (BFEs), or the Special Flood Hazard Area (SFHA). The LOMR officially revises the Flood Insurance Rate Map (FIRM) or Flood Boundary and Floodway Map (FBFM), and sometimes the Flood Insurance Study (FIS) report, and when appropriate, includes a description of the modifications.
The LOMR is generally accompanied by an annotated copy of the affected portions of the FIRM, FBFM, or FIS report.
LETTER OF MAP REVISION BASED ON FILL (LOMR-F): FEMA's modification of the Special Flood Hazard Area (SFHA) shown on the Flood Insurance Rate Map (FIRM) based on the placement of fill outside the existing regulatory floodway. The LOMR-F does not change the FIRM, FBFM, or FIS report.
CONDITIONAL LETTER OF MAP REVISION (CLOMR): A formal review and comment as to whether a proposed flood protection project or other project complies with the minimum NFIP requirements for such projects with respect to delineation of Special Flood Hazard Areas. A CLOMR does not revise the effective Flood Insurance Rate Map (FIRM) or Flood Insurance Study (FIS). Upon submission and approval of certified as-built documentation, a Letter of Map Revision (LOMR) may be issued by FEMA to revise the effective FIRM.
LOWEST FLOOR: The lowest floor of the lowest enclosed area (including basement or subgrade crawl space). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building's lowest floor; Provided, that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of 44 CFR Section 60.3 and this Section.
MAINTENANCE: The act of ongoing upkeep of existing structures required to keep channels in a condition adequate to support the conveyance of irrigation and drainage water (this does not include the complete replacement or substantial replacement of an existing structure). Maintenance is further defined as the care or upkeep of channels, works, appurtenances, easements, utility corridors and property; to keep in an existing state, specified state of repair, and efficiency; return to a former condition, elevation, place, and position; to preserve from failure or decline; or repair or renovate so as to return it to its original condition. Maintenance does not include dredging as defined herein.
MANUFACTURED HOME: A structure, transportable in one or more sections, built on a permanent chassis and designed to be used with or without a permanent foundation when connected to the required utilities. This includes Tiny Homes and Park Models. The term "manufactured home" does not include a "recreational vehicle."
MANUFACTURED HOME PARK OR SUBDIVISION: A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
MARKET VALUE: The building value, not including the land value and that of any accessory structures or other improvements on the lot. Market value is determined by the tax assessed values, unless revised by an independent certified appraisal (paid for by the property owner).
NEW CONSTRUCTION: For floodplain management purposes, a structure for which the start of construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures. Any construction started after April 4, 1984 (entry into the NFHP), and before the effective start date of this floodplain management section is subject to the section in effect at the time the permit was issued, provided the start of construction was within one hundred and eighty (180) days of permit issuance.
NONRESIDENTIA L STRUCTURE: A building, other than a residential structure or dwelling, or parts thereof, that is open to the public or for private use. The term nonresidential structure includes but is not limited to: structures used for places of assembly, education, business, maintenance, storage, manufacturing, and government.
OPERATION: The regular and reoccurring performance of typical work by an irrigation or drainage entity including, but not limited to, the delivery or drainage of water, measurement of water, and adjustment of irrigation and drainage works and all related appurtenances.
ORDINARY HIGH-WATER MARK: The line that the water impresses upon the soil by covering it for sufficient periods of time to deprive the soil of its vegetation and destroy its value for agricultural purposes. When the soil, configuration of the surface, or vegetation has been altered by human activity, the natural or ordinary high-water mark will be located where it would have been if this alteration had not occurred.
RECREATIONAL VEHICLE: A vehicle that is:
A. Built on a single chassis;
B. Four hundred (400) square feet or less when measured at the largest horizontal projection;
C. Designed to be self-propelled or permanently towed by a light duty truck; and
D. Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
REGULATORY FLOODWAY: See FEMA Regulatory Floodway Boundary
REPAIR: The restoration to good or sound conditions of any part of an existing structure, channel, channel bank, or service road for the purpose of maintenance (this does not include the complete replacement or substantial replacement of an existing structure). Repair does not include dredging as defined herein.
RESIDENTIAL STRUCTURE: A building used as a dwelling for one or more persons. The term residential structure includes, but is not limited to houses, family day care homes, group day care facilities, apartment buildings, lodging homes, dormitories, hotels, motels, hospitals, sanatoriums, and nursing homes. The term residential structure also includes accessory use areas used in conjunction with, and an integral part of, a residential structure.
RIPARIAN AREA: The land that directly abuts a natural body of water such as a river, lake, stream, creek, or coastal body of water and is within twenty-five feet (25') of the FEMA Regulatory Floodway Boundary.
SPECIAL FLOOD HAZARD AREA (SFHA): The areas in Ada County in the flood plain subject to a one percent (1%) or greater chance of flooding in any given year. For purposes of these regulations, the term "Special Flood Hazard Area" is synonymous in meaning with the phrase "area of special flood hazard." It also includes foothill or hillside tributary floodplain; and other areas determined by the floodplain administrator to be a hazard to public health, safety, and welfare due to flooding.
START OF CONSTRUCTION: Includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition placement, or other improvement was within one hundred and eighty (180) days of the permit date. The actual start means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading, and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure. For a substantial improvement, the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.
STRUCTURE: A walled and/or roofed building, including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.
SUBSTANTIAL DAMAGE (SD): Damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damaged condition would equal or exceed fifty percent (50%) of its market value before the damage occurred. See definition of "substantial improvement." Substantial damage also means flood- related damage sustained by a structure on two separate occasions during a ten (10) year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds twenty-five percent (25%) of the market value of the structure before the damage occurred.
SUBSTANTIAL IMPROVEMENT (SI): Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds fifty percent (50%) of the market value of the structure before the "start of construction" of the improvement. This term includes structures which have incurred "substantial damage," regardless of the actual repair work performed. The term does not, however, include either:
A. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official, and which are the minimum necessary to assure safe living conditions; or
B. Any alteration of a "historic structure," provided that the alteration will not preclude the structure's continued designation as a "historic structure" and the alteration is approved by variance issued pursuant to this Section.
VIOLATION: The failure of a structure or other development to be fully compliant with this Section. A structure or other development without the Finished Construction Elevation Certificate, other certifications, or other evidence of compliance required in 44 CFR Sections 60.3(b)(5), (c)(4), (c)(10), (d)(3), (e)(2), (e)(4), or(e)(5) is presumed to be in violation, see Chapter 8 of this Title, until such time as that documentation is provided.
G. Process:
1. Approval: Prior to the commencement of any development within any Special Flood Hazard Area, the property owner shall obtain approval of a floodplain permit.
2. Application: An application, including fees, shall be submitted to the Development Services Department, on forms provided by the department, along with all required information identified on the applicable floodplain checklist. The floodplain administrator will review the request and determine if additional information, certificates, or studies are required prior to commencement of development or manufactured home placement.
3. Permit Duration: The approval of a floodplain permit shall be limited to a two (2) year period in which the proposed improvements shall be completed to the satisfaction of the floodplain administrator.
4. Determination Of The Base Flood Elevation (BFE): The first item to accomplish for any proposed work in the special flood hazard area is to determine the BFE by any of the following:
a. A previous FEMA study or map. FEMA Zone AE will already have a BFE noted for use.
b. A flood elevation study (FES). FEMA Zone A will require the BFE to be established by the application. A FES shall be prepared by a professional engineer licensed in the state of Idaho and must be approved by the floodplain administrator prior to the commencement of any development. The study submitted shall include:
(1) A title;
(2) A table of contents;
(3) The location and description of the property;
(4) A scope of work;
(5) Analysis and documentation of methods and procedures to determine the flood elevation and any additional information required by this Section;
(6) A discussion of the proposed use in the existing floodplain and the surrounding land uses;
(7) A discussion of floodplain regulation compliance; and
(8) All other items identified on the floodplain checklist as may be applicable and/or as may be required by the floodplain administrator.
5. Once the BFE is determined the following standards apply:
a. A grading and drainage plan shall be submitted showing adequate drainage paths around structures.
b. For Residential Structures, the application shall include an Elevation Certificate on the most current FEMA Approved forms. The Elevation Certificate must show the lowest floor elevation (including basement or crawlspace) is two feet (2') above the BFE. New residential structure construction in the floodway is prohibited.
c. For Non-Residential Structures, the application shall include an Elevation Certificate on the most current FEMA Approved forms. The Elevation Certificate must show the lowest floor elevation (including basement or crawlspace) is two feet (2') above the BFE. OR the application shall include a Floodproofing Certificate on the most current FEMA approved forms. The Floodproofing Certificate must show floodproofing protection is provided up to two feet (2') above the BFE. New non-residential construction in the floodway is prohibited.
d. For pools, the application shall include an Elevation Certificate or Floodproofing certificate on the most current FEMA approved forms. The form must show flood protection is provided up to two feet (2') above the BFE. New pool construction in the floodway is prohibited.
e. For a pit, mine, or quarry, the application shall demonstrate that the extraction site will be designed to avoid river avulsion by a FES. The FES must be approved prior to commencement of the use or breaking ground. Gravel mining operations or excavations are not permitted within two hundred feet (200') of the top of riverbank regardless of floodway or floodplain designation. Material stockpiles and permanently installed structures shall not be located within the regulatory floodway. New pit, mine, or quarry construction and/or operation is prohibited in the floodway.
f. For a proposed subdivision, the application shall demonstrate that the subdivision shall be consistent in design and construction with the need to minimize flood damage. Public utilities and facilities including, but not limited to, sewer, gas, electrical, telephone, and water systems shall be located and constructed to minimize flood damage and certified by a professional engineer licensed in the state of Idaho. Adequate drainage shall be provided to reduce exposure to flood damage. All roads shall be elevated at two (2') above the established base flood elevation and allow flood water to pass under so that it does not act as a check dam. New subdivision construction is prohibited in the floodway.
g. For subdivisions, the SFHA boundary lines must be drawn on the final plat and a plat note(s) added designating the following:
(1) FEMA FIRM panel(s): #160xxxxxxC, and 160xxxxxxE, etc.;
(2) FIRM effective date(s): mm/dd/year;
(3) Flood Zone(s): Zone X, Zone A, Zone AE, A Zone, Zone D, etc.;
(4) Base Flood Elevation(s): AE xxxxxx.x ft., etc.; and
(5) The following statement: "Flood Zones are subject to change by FEMA and all land within a floodway or floodplain is regulated by Section 8-2-28 of the Ada County Code and FEMA and the Local Floodplain Authority."
h. For proposed work in a Foothill or Hillside tributary, the County Engineer may require an FES to determine that the proposed work will not result in any increase in flood levels within the community during the occurrence of the base flood discharge.
i. For new bridges, the proposed plan(s) shall show that all horizontal bridge supports are elevated two feet (2') above the BFE and that all supporting members are designed to withstand the flows and velocities of the base flood.
j. If the proposed work requires a change to the effective FEMA Map and/or FIS, then a LOMR shall be submitted to FEMA. Ada County may require the applicant submit a CLOMR to FEMA prior to work starting if the project scope warrants.
k. The following setbacks apply to all proposed work in the Special Flood Hazard Area and outside of the Special Flood Hazard Area:
Boise River Setback: Structures, parking areas, and fences shall be setback one hundred feet (100') from the Floodway line of the Boise River. Structures, parking areas and fences shall also be five feet (5') from the boundary of all dedications or easements granted to the County for recreational purposes in excess of sixty-five feet (65').
Great Blue Heron Rookeries Setback: If Great Blue Heron Rookeries have been identified and documented by the County or Idaho Fish and Game Department, a three-hundred-foot (300') setback from the rookery location, applies to development within the Boise River Greenway.
Bald Eagle Nest Setback: If Bald Eagle nests have been identified and documented by the County or Idaho Fish and Game Department, a two-hundred-foot (200') setback from the nest location, applies to development within the Boise River Greenway.
Riparian Setback: Grading including vegetation clearing or thinning is not allowed within one hundred feet (100') of the FEMA Regulatory Floodway Boundary unless required for public safety and approved in writing prior to work.
l. For proposed fences and walls, fence construction is prohibited in the Floodway. Proposed fencing in the floodplain shall be reviewed on a case-by-case basis to confirm flood flows will not be obstructed.
m. For proposed projects that have Functionally Dependent Use, functionally dependent uses shall follow the standards of this Section, provided that the use does not cause a rise in the BFE within a regulatory floodway, and the structure and other development must be protected by methods that minimize flood damages.
n. For habitat restoration and bank stabilization projects, a floodplain permit is required. Although these projects will require a No-Rise Certification, these projects may not require a full hydraulic analysis if the permit shows equal or greater flood water conveyance by standard engineering practice.
o. For irrigation district work, the floodplain permit will be governed by the Guidance Letter issued to Ada County from the Idaho Department of Water Resources dated 5-20-2019, and any following amendments from IDWR.
H. Land Use Restrictions For Special Flood Hazard Areas:
1. Land Use Restrictions: AE, A, and D Zones and the Regulatory Floodway: Despite any other regulations of this Title, Critical Facilities, and the following uses, including any new construction or substantial improvements to such uses, are prohibited in the regulatory floodway, AE, A, or D zone where the base flood elevations have been determined or estimated:
Explosive manufacturing or storage.
Flammable substance storage.
Foster home, group.
Gasoline, diesel, or alternative fuel sales.
Junkyard or automobile wrecking yard.
Manufacture and/or storage of materials that are buoyant, flammable, toxic, radioactive, or explosive or may present a hazard to public health or safety in time of flooding.
Manufacture of electronic or electrical products.
Manufacture or processing of hazardous chemicals or gases.
Manufactured home storage.
Portable classroom.
Sanitary landfill, restricted.
School, vocational or trade.
Soil or water remediation.
Tannery.
Vehicle impound yard.
Stormwater Facilities
Sanitary Sewer Facilities.
I. Required Findings: In order to approve the application, the decision-making body shall find that the proposed development including, but not limited to, new construction, placement of manufactured home or substantial improvement, meets the general regulations and standards as set forth in this Section, and as such, shall find that the proposed work would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.
J. Appeals:
1. Appeals of determinations made by the floodplain administrator shall be heard by the board and shall comply with procedures of Section 8-6-13 of this Title.
2. Appeals which allege there is an error in any requirement, decision, or determination made by the floodplain administrator in the enforcement or administration of this Section, shall be supported by technical and scientific evidence which shall include, but is not limited to, the following items:
a. A copy of the recorded plat map showing the property or, if there is no recorded plat map, a scaled vicinity map showing the property.
b. A topographic map showing ground elevation contours and a line representing the area subject to inundation by the base flood.
c. Certification by a professional engineer licensed in the state of Idaho of the elevation of the lowest floor (including basement and/or crawl space), the elevation of any fill, the date on which the fill was placed, and the elevation to which any structure has been floodproofed.
3. The board shall base their decision on an appeal on the specific and technical evidence in the record.
K. Variances To Flood Insurance Program Standards:
1. Purpose: The purpose of this Section is to provide a relief from national flood insurance program standards as they pertain to a physical piece of property and at the same time not jeopardizing sufficient flood protection.
2. Applicability: Variances may be issued consistent with the FEMA variance and exception regulations as set forth in 44 CFR Chapter 1, Section 60.6.
3. Process:
a. An application and fees, as set forth in Section 8-6-5 of this Title, shall be submitted to the Director on forms provided by the Development Services Department.
b. The Board shall consider all technical evaluations, all relevant factors, standards specified in other Sections of this Section including, but not limited to, the expected heights, velocity, duration, rate of rise, and sediment transport of the floodwaters if applicable, expected at the site.
c. The Board may attach such conditions to the granting of variances as it deems necessary to further the purposes of this Section.
d. The Board shall apply the findings listed in subsection 4 of this subsection to review the variance.
e. Anyone to whom a variance is granted shall be given written notice that:
(1) The issuance of the variance to construct a structure below the base flood level will result in increased premium rates for flood insurance up to amounts as high as twenty-five dollars ($25.00) for one hundred dollars ($100.00) of insurance coverage; and that such construction below the base flood level increases the risk to life and property.
4. Required Variance Findings:
a. The proposed use adequately mitigates any danger that materials may be swept onto other properties to the injury of others;
b. The proposed use adequately mitigates the danger to life and property due to flooding or erosion damage;
c. The proposed use minimizes the susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;
d. The proposed use provides an important service to Ada County;
e. The proposed use shall not cause extraordinary public expense in providing governmental services during post-flood conditions including maintenance and repair of public utilities and facilities such as sewer, gas, electrical, water systems, and streets and bridges;
f. The proposed use shall not have available alternative locations that are not subject to flooding or erosion damage;
g. The proposed use provides for safe access to the property in times of flood for ordinary and emergency vehicles;
h. The variance shall not conflict with existing local laws or articles;
i. The variance is the minimum necessary, considering the flood hazard, to afford relief;
j. The variance shall not result in increased flood heights during the base flood discharge;
k. The variance shall not cause fraud on or victimization of the public; and
l. Failure to grant the variance would result in exceptional hardship.
5. Required Findings For Historic Structures: The following additional findings are required for variances for historic structures:
a. The proposed repair or rehabilitation of the structure will not preclude the structure's continued designation as a historic structure; and
b. The variance is the minimum necessary to preserve the historic character and design of the structure.
(Ord. 1002, 10-28-2025)
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8-2-23: USE TABLE:8-2-24: BOISE AIR TERMINAL AIRPORT INFLUENCE 8-2-25: WILDLAND-URBAN INTERFACE (WUI) OVERLA8-2-26: SOUTHWEST PLANNING AREA (SPA) OVERLAY8-2-27: AREA OF MILITARY INFLUENCE (AMI) OVER8-2-28: FLOOD HAZARD (FH) OVERLAY DISTRICT:8-2-29: BOISE RIVER GREENWAY (BRG) OVERLAY DI8-2-30: HILLSIDE (HS) OVERLAY DISTRICT:8-2-31: TEN MILE CREEK OVERLAY DISTRICT (RESECHAPTER 3 DEVELOPMENT STANDARDS8-3-1: PURPOSE AND APPLICABILITY:8-3-2: GENERAL STANDARDS:8-3-3: ACCESS:8-3-4: BUILDING DESIGN:8-3-5: INFRASTRUCTURE:
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