“Accessory structure” means a structure that is on the same parcel of property as a principal structure, the use of which is incidental to the use of the principal structure. For floodplain management purposes, the term includes only accessory structures used for parking and storage.

“Appeal” means a request for a review of the Floodplain Administrator’s interpretation of any provision of this chapter or a request for a variance. Appeals are heard and decided by the Floodplain Board.

“Area of shallow flooding” means a designated zone AO or AH on a community’s Flood Insurance Rate Map (FIRM) with a one percent (1%) or greater annual chance of flooding to an average depth of one (1) to three (3) feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow.

“Base flood” means a flood having a one percent (1%) chance of being equaled or exceeded in any given year.

“Base flood elevation (BFE)” means the computed elevation to which floodwater is anticipated to rise during the base flood.

“Basement” means any area of a structure with a subgrade floor (i.e., below the adjacent ground level) on all sides.

Building. See “Structure.”

“Community” means any state or area or political subdivision thereof, or any Indian tribe, authorized tribal organization, or authorized Native organization, which has authority to adopt and enforce floodplain management regulations for the areas within its jurisdiction.

Critical Facility. Refer to Section 17-5-8(D).

“Detention system” means a type of flood control system which delays the downstream progress of floodwaters in a controlled manner, generally through the combined use of a temporary storage area and a metered outlet device, which causes a lengthening of the duration of the flow and thereby reduces downstream flood peaks.

“Development” means any manmade change to improved or unimproved real estate, including but not limited to structures, mining, dredging, filling, grading, paving, excavation or drilling operations, and storage of materials and equipment.

“Dwelling” means a habitable structure.

“Elevation certificate” means an administrative tool of the National Flood Insurance Program (NFIP) that is used to provide elevation information necessary to ensure compliance with community floodplain management ordinances, to determine the proper insurance premium rate, and to support a request for a letter of map amendment (LOMA) or letter of map revision based on fill (LOMR-F).

“Encroachment” means the advance or infringement of uses, landscape vegetation, fill, excavation, permanent structures, or development into a floodplain that may impede or alter the flow capacity of a floodplain. An equal degree of encroachment is a standard applied to the evaluation of the effects of the encroachment on increases in flood heights. It assumes that an encroachment, if permitted, may confer on all property owners on both sides of the watercourse an equal right to encroach to the same degree within that reach. Since the factors affecting hydraulic efficiency are usually not uniform within a reach, this standard will usually not result in equal measured distances between the regulatory floodway and the regulatory floodplain of the watercourse.

“Erosion” means the process of the gradual wearing away of landmasses. This peril is not, per se, covered under the National Flood Insurance Program.

“Erosion hazard area” means lands adjoining a watercourse that is regulated by this chapter which are deemed by the Town Engineer to be subject to flood-related erosion, pursuant to the Town’s adopted drainage criteria manual.

“Erosion setback” means the minimum horizontal distance between a structure or permanent feature and the channel bank necessary to protect the structure/feature from flood-related erosion damage. For method to be used for determination of the erosion setback, see the adopted Town of Oro Valley drainage criteria manual.

“Existing manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are affixed (including, at a minimum, the installation of utilities, construction of streets, and either final site grading or the pouring of concrete slabs) was completed before December 4, 1979, the effective date of the Flood Insurance Rate Maps adopted by the Town of Oro Valley.

“Expansion to an existing manufactured home park or subdivision” means preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads).

“Federal Emergency Management Agency (FEMA)” means an agency of the Federal government responsible for programs of disaster response and recovery, disaster preparedness, hazard mitigation, flood insurance, and other programs of technical and financial assistance.

“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from: (1) the overflow of floodwaters; (2) the unusual and rapid accumulation or runoff of surface waters from any source; and/or (3) 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 this definition.

“Flood Insurance Rate Map (FIRM)” means the official map on which the Federal Emergency Management Agency has delineated both the special flood hazard areas and the risk premium zones applicable to the community.

“Flood Insurance Study (FIS)” means the official report provided by Federal Emergency Management Agency that includes flood profiles, the Flood Insurance Rate Map, and the water surface elevation of the base flood.

“Flood protection system” means those physical structural works for which funds have been authorized, appropriated, and expended; and which have been constructed specifically to modify flooding in order to reduce the extent of the area within a community subject to designation as a regulatory floodplain as well as the extent and depths of associated flooding. Such a system typically includes dams, reservoirs, levees or dikes. These specialized flood-modifying works are those constructed in conformance with sound engineering standards.

“Floodplain” or “flood-prone area” means any land area susceptible to being inundated by water from any source (see “flood” or “flooding”).

“Floodplain Administrator” means the Town Engineer, or their designee, whose duty it is to oversee administration and enforcement of the floodplain management regulations contained in this chapter.

“Floodplain Board” means the Town Council of Oro Valley, at such times as they are engaged in the enforcement of this chapter.

“Floodplain management” means the operation of an integrated natural resource management program encompassing corrective and preventive measures for reducing flood and erosion damage. Floodplain management includes but is not limited to emergency preparedness planning, flood control works and floodplain management regulations.

“Floodplain management regulations” means this chapter and other zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as grading and erosion control), and other applications of legal and regulatory authority that control use of, and development in, flood-prone areas. This term describes Federal, State, or local regulations, and any combination thereof, which provide standards for preventing and reducing flood loss and damage.

“Floodplain use permit” (also “permit for development in a floodplain”) means an official document that authorizes special activity within regulatory floodplains or erosion hazard areas of Oro Valley.

“Flood-proofed” means a watertight structure with walls substantially impermeable to the passage of water, and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy, and by means other than elevation.

“Flood-proofing” means any combination of structural and nonstructural additions, changes, or adjustments to nonresidential structures that reduces or eliminates flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents by means other than elevation.

“Flood-related erosion” means the collapse or subsidence of land along the shore of a lake or other body of water as a result of 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 a flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding.

Floodway. See “regulatory floodway.”

“Floodway fringe” means that area of the floodplain lying on either side of a regulatory floodway where encroachment may be permitted.

“Functionally dependent use” means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long-term storage or related manufacturing facilities.

“Governing body” is the local governing unit (i.e., county or municipality) empowered to adopt and implement regulations providing for the public health, safety, and general welfare of its citizenry.

“Hardship” means that the physical characteristics of the property in question are so unusual, exceptional, and peculiar to the property that a variance regarding its use may be requested and granted. Mere economic or financial hardship alone is not exceptional. Inconvenience, aesthetic considerations, physical handicaps, personal preferences, or the disapproval of one’s neighbors likewise cannot, as a rule, be construed to qualify as an exceptional hardship. All of these problems can be resolved through other means without granting a variance, even if the alternative is more expensive, requires the property owner to build elsewhere, or means that the parcel must be put to a different use than originally intended.

“Highest adjacent grade” means the highest natural elevation of the ground surface immediately adjacent to a structure prior to construction of the proposed walls of a structure.

“Historic structure” means any structure that is:

“Levee” means a human-made structure, usually an earthen embankment designed and constructed in accordance with sound engineering practices, for the purpose of containing, controlling, or diverting the flow of water so as to provide protection from temporary flooding.

“Lowest floor” means the lowest floor of the lowest enclosed area including the basement (see “basement” definition) or crawl space under a manufactured home if it is not vented. 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 to be the lowest floor of a structure; provided, that such enclosure is not built so as to render the structure in violation of the applicable nonelevation design requirements of this chapter.

“Manufactured home” means a structure, transportable in one (1) or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when attached to the required utilities. The term “manufactured home” does not include a “recreational vehicle.”

“Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two (2) or more manufactured home lots for rent or sale.

“Market value” means the determination of the estimated cost to replace the structure in new condition and adjusting that cost figure by the amount of depreciation that has accrued since the structure was constructed. The cost of replacement of the structure shall be based on a square foot cost factor determined by reference to a building cost estimating guide recognized by the building construction industry. The amount of depreciation shall be determined by taking into account the age and physical deterioration of the structure and functional obsolescence as approved by the Floodplain Administrator but shall not include economic or other forms of external obsolescence. Use of replacement costs or accrued depreciation factors different from those contained in recognized building cost estimating guides may be considered only if such factors are included in a report prepared by an independent professional appraiser and supported by a written explanation of the differences. Alternatively, the market value is the valuation made by the Pima County Assessor’s Office.

“Mean sea level” means, for purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD) of 1929, North American Vertical Datum of 1988 (NAVD ’88), or other datum to which base flood elevations shown on a community’s Flood Insurance Rate Map are referenced.

“National Flood Insurance Program (NFIP)” means a program administered by FEMA that makes Federally backed flood insurance available for purchase by individuals that live in NFIP participating communities.

New Construction. For the purposes of determining insurance rates, structures for which the start of construction commenced on or after the effective date of an initial Flood Insurance Rate Map or after December 31, 1974, whichever is later, and includes any subsequent improvements to such structures. For floodplain management purposes, “new construction” means structures 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.

“Obstruction” includes, but is not limited to, any dam, wall, embankment, levee, dike, pile, abutment, protection, excavation, channelization, bridge, conduit, culvert, structure, wire, fence, rock, gravel, refuse, fill, structure, vegetation, or other material in, along, across, or projecting into any watercourse which may alter, impede, retard, or change the direction and/or velocity of the flow of water, or which due to its location influences its propensity to snare or collect debris carried by the flow of water, thereby reducing its likelihood of being carried downstream as well as reducing the channel’s ability to convey flow.

“One hundred (100) year flood” means the flood having a one percent (1%) chance of being equaled or exceeded in any given year (see “base flood”). Also referred to as the one percent (1%) annual exceedance probability flood (one percent (1%) AEP flood).

“Permit for development in a floodplain” (also referred to as a “floodplain use permit”) is an official document issued by the Town of Oro Valley authorizing performance of specific activity in any regulatory floodplain or erosion hazard area after it has been determined to be reasonably safe from flooding and erosion. These permits are required to ensure that proposed development projects meet the requirements of the NFIP and the provisions of this chapter. Examples include grading permits, building permits, and floodplain use permits.

“Person” means an individual, firm, partnership, association or corporation, or agent of the aforementioned groups, or the State of Arizona or its agencies or political subdivisions.

“Program” means the National Flood Insurance Program authorized by 42 U.S.C. 4001 through 4128, or as authorized by subsequent Federal statutes.

“Reach” is a hydraulic engineering term to describe longitudinal segments of a stream or watercourse. A reach will generally include the segment of the flood hazard area where flood heights are primarily controlled by manmade or natural obstructions or constrictions. In an urban area, an example of a reach would be the segment of a stream or watercourse between two (2) consecutive bridge crossings.

“Recreational vehicle” means a vehicle that is:

“Regulatory flood elevation” means an elevation that is one (1) foot above the calculated water surface elevation of the base flood, as established by the State of Arizona for floodplain management purposes.

“Regulatory floodplain or flood-prone area” means that portion of the geologic floodplain associated with a watercourse, including its channel, or any other floodplain or flood-prone area that would be inundated by the base flood, including all base floods where the base flood peak discharge is one hundred (100) cubic feet per second or greater, those areas that are subject to sheet flooding except when the maximum potential contributing watershed area is less than twenty (20) acres, those areas identified on subdivision plats or development plans, those areas designated by FEMA, including areas designated as shaded Zone X as well as those areas that the Floodplain Administrator, using the best available data, has determined is subject to a flood hazard during the base flood.

“Regulatory floodway” means the channel of a 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 amount.

“Remedy a violation” means to bring the structure or other development into compliance with State or local floodplain management regulations, or, if this is not possible, to reduce the impacts of its noncompliance. Ways that impacts may be reduced include protecting the structure or other affected development from flood damages, implementing the enforcement provisions of this chapter, otherwise deterring future similar violations, or reducing Federal financial exposure with regard to the structure or other development.

“Repetitive loss structure” means a structure, covered by a contract for flood insurance issued pursuant to the National Flood Insurance Act, that has incurred flood-related damage on two (2) occasions during any ten (10) year period ending on the date of the event for which a second claim is made, and for which the cost of repairing the flood damage, on average, equaled or exceeded twenty-five percent (25%) of the market value of the structure at the time of each such flood event. In addition to the current claim, the NFIP must have paid the previous qualifying claim.

“Retention system” means a type of flood control system that stops the downstream progress of floodwater by employing methods of total containment which generally involve creation of storage areas that incorporate infiltration devices, such as dry wells, to dispose of stored waters, principally by percolation over some specified period of time, thereby eliminating basin contributions to downstream flood peaks or flood volumes.

“Riverine” means relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.

Sheet Flow Area. See “area of shallow flooding.”

“Special flood hazard area (SFHA)” means an area in the regulatory floodplain subject to a one percent (1%) or greater chance of flooding in any given year. SFHAs are shown on a Flood Insurance Rate Map as Zone A, AO, AE, AH or A0.

“Start of construction” includes substantial improvement or other proposed new development, 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 the time period when the permit was active. 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 the installation of streets and/or walkways, the installation on the property of accessory structures, 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 structure, whether or not that alteration affects the external dimensions of the structure.

“Structure” means a walled and roofed building, including gas or liquid storage tanks, principally above ground and affixed to a permanent site. This term also refers to a manufactured home on a permanent foundation.

“Substantial damage” means 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 the market value of the structure before the damage occurred.

“Substantial improvement” means any reconstruction, rehabilitation, addition, or other improvement to a structure, the total 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:

“Variance” means a grant of relief from the requirements of this chapter that is granted by the Floodplain Administrator or the Floodplain Board (for FEMA floodplains) upon a finding that strict enforcement of the provisions would cause undue hardship owing to circumstances unique to the individual property for which the variance is granted, and not caused by the applicant for said variance.

“Violation” means the failure of a structure or other development to be fully compliant with the Town of Oro Valley floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required by this chapter is presumed to be in violation until such time as such documentation is provided. “Violation” also means unauthorized construction, grading, encroachment, diversion, or lack of maintenance of private drainage structures.

“Water surface elevation” means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929 or the North American Vertical Datum (NAVD) of 1988 (or other datum, where specified), of floods of various magnitudes and frequencies in the floodplains of riverine and sheetflow areas.

“Watercourse” means a lake, river, creek, stream, wash, arroyo, channel, or other topographic feature on or over which waters flow at least periodically. “Watercourse” includes specifically designated areas in which substantial flood damage may occur, including regulatory floodplains as designated by FEMA or the Town of Oro Valley.

“Zone A (unnumbered)” is a special flood hazard area identified by FEMA that is subject to inundation from a one hundred (100) year flood event. Because detailed hydraulic analyses have not been performed, no base flood elevation or depths are shown. Mandatory flood insurance requirements apply.

“Zone AE” is a special flood hazard areas subject to inundation by the one hundred (100) year flood determined by a Flood Insurance Study (FIS). Base flood elevations are shown within these zones and mandatory flood insurance requirements apply.

“Zone AH” is a special flood hazard area subject to inundation by one hundred (100) year shallow flooding (usually areas of ponding) with average depths between one (1) and three (3) feet. Base flood elevations derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance requirements apply.

“Zone AO” is a special flood hazard area subject to inundation by one hundred (100) year shallow flooding, usually resulting from sheet flow on sloping terrain, with average depths between one (1) and three (3) feet. Average flood depths derived from detailed hydraulic analyses are shown within this zone. Mandatory flood insurance requirements apply.

“Zone X shaded” (or “shaded Zone X”) is an area determined by a Flood Insurance Study as having moderate or minimal hazard from flooding. There are four classifications depending on location: (1) area of one hundred (100) year flood with average depths of less than one (1) foot; (2) area with drainage areas less than one (1) square mile; (3) area protected by an accredited levee from one hundred (100) year flood; and (4) area of five hundred (500) year flood. Buildings or other improvements in this zone could be flooded by severe, concentrated rainfall, in the absence of adequate drainage systems. Flood insurance is available in participating communities, but it is not required. In the Town of Oro Valley only the third classification applies (i.e., protected by levees). ((O)21-06, 11/17/2021; (O)17-04, 04/05/2017; (O)05-35, 10/05/2005)