Chapter 14.10


14.10.010    Abbreviations.

14.10.020    Definitions.

14.10.010 Abbreviations.

The following common abbreviations are used throughout this title:


Arizona Department of Water Resources


Base Flood Elevation


Cubic Feet per Second


Conditional Letter of Map Revision


Erosion Hazard Setback or Erosion Hazard Setback Limit


Federal Emergency Management Agency


Finished Floor Elevation


Federal Insurance Administration


Flood Insurance Study


Flood Insurance Rate Map


Letter of Map Revision


Letter of Map Revision (by Fill)


National Flood Insurance Act


National Flood Insurance Program


National Geodetic Vertical Datum (of 1929)


North American Vertical Datum (of 1988)


Special Flood Hazard Area

[Ord. 2020-147 § 4; Ord. 2011-059 § 4.]

14.10.020 Definitions.

Unless specifically defined below, words or phrases used in this title shall be interpreted so as to give them the meaning they have in common usage and to give this title its most reasonable application.

“Accessory structure” means a structure that is on the same parcel of property as the principal structure, the use of which is incidental to the use of the principal structure.

“All-weather access” means access considered traversable by normal passenger vehicles, defined as a permanent, durable material with adequate protection against scour and erosion and having a depth of water no more than 12 inches above the roadway surface during a base flood.

“Appeal” means a request for a review of the floodplain administrator’s interpretation of any provision of this title or a request for a floodplain variance.

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

“Area of special flood hazard” is synonymous with special flood hazard area (SFHA).

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

“Base flood elevation (BFE)” means the water surface elevation associated with the base flood.

“Basement” means any area of a building having its floor sub-grade (below ground level) on all sides.

Building. See “Structure.”

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

“Conditions and restrictions” means standard requirements which are placed on a parcel of land, the development permit applicant and the parcel owner by the floodplain administrator as a condition of the applicant’s or owner’s use of the floodplain.

“Critical facilities” means facilities that are considered critical in their need to remain serviceable during a major flood event or that their inundation by flood waters poses a high risk to the health, safety or welfare of the community.

“Detention” means a drainage system which delays the downstream progress of flood waters 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 flow and thereby reduces downstream flood peaks.

“Developer” means any person, group or entity proposing or constructing a development as defined by this title.

“Development” means any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations, and storage of materials and equipment located within the area of special flood hazard.

“Encroachment” means the advance or infringement of uses, fill, excavation, buildings, permanent structures or development into a floodplain, which may impede or alter the flow capacity of a floodplain.

“Erosion” means the process of the gradual or avulsive wearing away of land masses due to the flow of water. Erosion is not, per se, covered under the National Flood Insurance Program (NFIP).

“Erosion hazard setback (EHS)” means a prescribed horizontal distance measured from the primary channel bank of an incised channel or from the design storm’s water surface limits for a non-incised channel for the purpose of providing a measure of safety against lateral erosion.

“Expansion to an existing manufactured home park or subdivision” means the 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).

“Five-hundred-year flood (500-year flood)” means the flood having a two-tenths percent chance of being equaled or exceeded in any given year.

“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from: (1) the overflow of flood waters; (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 FEMA 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 FEMA that includes flood profiles, FIRMs, and the water surface elevation of the base flood.

“Flood-proofing” means any combination of structural and nonstructural 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 by means other than elevating.

“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.

“Flood zones (FEMA defined)”:

1. Zone X: Areas determined to be outside of the two-tenths percent annual chance floodplain.

2. Zone X (shaded): Areas within the limits of the two-tenths percent annual chance flood; areas of one percent annual chance flood with average depths of less than one foot or with drainage areas less than one square mile; and areas protected by levees with a one percent annual chance flood.

3. Zone A: SFHA with no base flood elevations determined.

4. Zone AE: SFHA with base flood elevations determined by the flood insurance study for Pima County.

5. Zone AH: SFHA with flood depth of one to three feet (usually areas of ponding); base flood elevations determined by the flood insurance study for Pima County.

6. Zone AO: SFHA with flood depths of one to three feet (usually sheet flow on sloping terrain); average depths determined. For areas of alluvial fan flooding, velocities also determined. The FIRMs show the depth in one-foot increments and velocities in one-foot-per-second increments.

7. Zone AE Floodway: That portion of a regulated watercourse’s SFHA which was delineated using an encroachment analysis and demarcates the limits of maximum encroachment from both sides of the floodplain without increasing the BFE more than one foot. See also definition for “Floodway.”

“Floodplain” or “flood-prone area” means any land area susceptible to being inundated by rain water runoff. This includes FEMA special flood hazard areas, areas platted on accepted town plans as being flood prone or locally regulated areas that may be inundated by water during a base flood.

“Floodplain administrator” means the individual appointed to administer and enforce the floodplain management regulations. Unless otherwise stated, the town engineer is the floodplain administrator.

“Floodplain board” means the town council of the town, at such times as they are engaged in the enforcement of this title.

“Floodplain management” means the operation of an overall program of corrective and preventive measures for reducing flood damage and preserving or enhancing, where possible, natural resources within the floodplain, including but not limited to emergency preparedness plans, flood control works and floodplain management regulations.

“Floodplain management regulations” means this title and other zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as grading and erosion control) and other application of police power, which control development in flood-prone areas. This term describes federal, state or local regulations in any combination thereof, which provide standards for preventing and reducing flood loss and damage.

“Floodway” means 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. Also referred to as “regulatory floodway.”

“Floodway fringe” means that area of the floodplain on either side of the regulatory floodway where encroachment may occur.

“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 or port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, but does not include long-term storage or related manufacturing facilities.

“Governing body” means the town council of the town, which is empowered to adopt and implement regulations to provide for the public health, safety and general welfare of the citizens of the town.

“Hardship” related to Chapter 14.30 STC (Floodplain Variance Procedure) means the exceptional hardship which would result from a failure to grant the requested floodplain variance. The governing body requires that the floodplain variance be exceptional, unusual and peculiar to the property involved. 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, qualify as an exceptional hardship. All of these problems can be resolved through other means without granting a floodplain variance, even if the alternative is more expensive, or requires the property owner to build elsewhere or put the parcel to a different use than originally intended.

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

“Historic structure” means any structure that is:

1. Listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior (Secretary) as meeting the requirements for individual listing on the National Register;

2. Certified or preliminarily determined by the Secretary as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;

3. Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary; or

4. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:

a. By an approved state program as determined by the Secretary; or

b. Directly by the Secretary in states without approved programs.

“Locally regulated floodplain” means floodplains in the town associated with washes and/or sheet flow areas having a base flood discharge of 100 cfs or more.

“Lowest floor” means the lowest floor of the lowest enclosed area, including basement (see “Basement” definition). 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 nonelevation design requirements of this title.

“Manufactured home” means a structure, transportable in one 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 manufactured home lots for sale or rent per STC Title 18 (Zoning).

“Market value” is determined by estimating the 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.

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

“New construction” means, for the purposes of determining insurance rates, structures for which the start of construction commenced on or after the effective date of an initial FIRM 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.

“Nonconforming use” means an existing legal use that does not comply with this title and was either:

1. Constructed prior to August 3, 1984, which predates the requirement for written authorization for development within a floodplain; or

2. Constructed on or after August 3, 1984, in compliance with the terms and conditions of the written authorization in effect at the time of construction; or

3. Constructed prior to the flood hazard being identified.

“Obstruction” includes, but is not limited to, any dam, wall, wharf, embankment, levee, dike, pile, abutment, protection, excavation, channelization, bridge, conduit, culvert, building, 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 due to its location, its propensity to snare or collect debris carried by the flow of water or its likelihood of being carried downstream.

“One-hundred-year flood (100-year flood)” is a common name for the flood having a one percent chance of being equaled or exceeded in any given year. (See “Base flood” definition.)

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

“Recreational vehicle” means a vehicle that is:

1. Built on a single chassis;

2. Four hundred square feet or less when measured at the largest horizontal projection;

3. Designed to be self-propelled or permanently towable by a light duty truck;

4. Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.

“Regulatory flood elevation” means an elevation one foot above the base flood elevation for a watercourse for which the base flood elevation has been determined or as determined by the criteria developed by the director of ADWR for all other watercourses.

“Regulatory floodplain” means an area 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 100-year peak discharge is 100 cfs or greater.

Regulatory Floodway. See “floodway.”

“Retention” means a drainage system which stops the downstream progress of flood waters by employing methods of containment and storage and uses infiltration, evaporation or re-use to dispose of stored waters, thereby eliminating basin contributions to the downstream flood peaks or volumes.

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

“Special flood hazard areas (SFHA)” means those areas that are subject to flooding by the one percent annual chance flood as defined by the flood insurance rate map (FIRM). The special flood hazard areas include Zones A, AE, AH, AO, AR, A99, V, and VE. The NFIP’s floodplain regulations must be enforced in special flood hazard areas (SFHA), and the purchase of flood insurance is mandatory in these areas.

“Start of construction” includes proposed new development, including 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 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” means a walled and roofed building, including a gas or liquid storage tank, which is principally above ground, as well as a manufactured home. “Structure” for insurance coverage purposes means a walled and roofed building, other than a gas or liquid storage tank, that is principally above ground and affixed to a permanent site, as well as a manufactured home on a permanent foundation. For the latter purpose, the term includes a building while in the course of construction, alteration or repair, but does not include building materials or supplies intended for use in such a construction, alteration or repair, unless such materials or supplies are within an enclosed building on the premises.

“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 50 percent of the market value of the structure before the damage occurred.

“Substantial improvement” means any reconstruction, rehabilitation, addition or other improvement of a structure, the cost of which equals or exceeds 50 percent 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:

1. 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

2. Any alteration of a historic structure; provided, that the alteration would not preclude the structure’s continued designation as a historic structure.

“Unlined” means not afforded channel lining, bank protection, or bank stabilization for purposes of resisting erosion.

“Variance, floodplain” means a grant of relief from the requirements of this title that permits construction in a manner that would otherwise be prohibited by this title.

“Violation” means the failure of a structure or other development to be fully compliant with the community’s floodplain management regulations. A structure or other development without the elevation certificate, other certifications or other evidence of compliance required in this title is presumed to be in violation until that documentation is provided.

“Water surface elevation” means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929 or North American Vertical Datum (NAVD) of 1988 of floods of various magnitudes and frequencies in the floodplains of riverine and ponding areas. See also “Base flood elevation.”

“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 (e.g., the regulatory floodplain). [Ord. 2020-147 § 4; Ord. 2011-059 § 4.]