A. Abbreviations. The following common abbreviations are used throughout this chapter:
1. ADWR: Arizona department of water resources
2. BFE: Base flood elevation
3. CFS: Cubic feet per second
4. CLOMR: Conditional letter of map revision
5. EHS(L): Erosion hazard setback or erosion hazard setback limit
6. FEMA: Federal emergency management agency
7. FFE: Finished floor elevation
8. FIS: Flood insurance study
9. FIRM: Flood insurance rate map
10. LOMA: Letter of map amendment
11. LOMR: Letter of map revision
12. LOMR-F: Letter of map revision based on fill
13. NGVD: National geodetic vertical datum of 1929
14. NAVD: North American vertical datum of 1988
15. NFIP: National flood insurance program
16. RFE: Regulatory flood elevation
17. SFHA: Special flood hazard area
B. Definitions. Unless specifically defined below, words or phrases used in this chapter shall be interpreted so as to give them the meaning they have in common usage and to give this chapter its most reasonable application.
1. Accessory Structure. A structure on the same parcel of property as a principal structure and 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 that are less than 600 square feet.
2. All-weather access. 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.
3. Appeal. A request for a review of the floodplain administrator’s interpretation of any provision of this chapter or a request for a floodplain variance.
4. Area of shallow flooding. 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.
5. Base flood. The flood having a one percent chance of being equaled or exceeded in any given year.
6. Base flood elevation (BFE). The computed elevation to which floodwater is anticipated to rise during the base flood.
7. Basement. Any area of a building having its floor sub-grade (below ground level) on all sides.
8. Building. See “structure.”
9. Conditions and restrictions. 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.
10. Community. 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.
11. Critical facilities. 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.
12. Detention. 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.
13. Development. Any man-made 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 special flood hazard area.
14. Elevation certificate. An administrative tool of the NFIP that is used to provide elevation information necessary to ensure compliance with community floodplain management ordinance, to determine the proper insurance premium rate. and to support a request for a LOMA or LOMR-F.
15. Encroachment. The advance or infringement of uses, plant growth, fill, excavation, buildings, permanent structures or development into a floodplain, which may impede or alter the flow capacity of a floodplain.
16. Erosion. The process of the gradual or avulsive wearing away of land masses due to the flow of water.
17. Erosion hazard setback (EHS). 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.
18. Existing manufactured home park or subdivision. A manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, construction of streets and either final site grading or the pouring of concrete slabs) is completed before July 9, 1984, the date of the town's first floodplain management ordinance.
19. Expansion to an existing manufactured home park or subdivision. 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).
20. Five hundred year flood (500-year flood). The flood having a 0.2% chance of being equaled or exceeded in any given year.
21. Flood or flooding. A general and temporary condition of partial or complete inundation of normally dry land areas from:
a. the overflow of flood waters;
b. the unusual and rapid accumulation or runoff of surface waters from any source; and/or
c. 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.
22. Flood insurance rate map (FIRM). The official map on which FEMA has delineated both the special flood hazard areas and the risk premium zones applicable to the community.
23. Flood insurance study (FIS). The official report provided by FEMA that includes flood profiles, FIRM, and the water surface elevation of the base flood.
24. Flood zones (FEMA defined):
a. Zone X. Area determined to be outside the 0.2% annual chance floodplain.
b. Zone X-500. Area free from a base flood due to a manmade protective structure or an area with base flood elevations or sheet flow elevations less than one foot. This area is also known as shaded zone X.
c. Zone A. SFHA with no base flood elevations determined.
d. Zone AE. SFHA with base flood elevations determined by the flood insurance study for Pima county.
e. Zone AH. SFHA with flood depths of one to three feet (usually areas of ponding); base flood elevations determined by the flood insurance study for Pima county.
f. 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.
g. Zone AE floodway. That portion of a regulated watercourse’s SFHA which must remain clear of any development. See also definition for floodway.
25. Floodplain or flood-prone area. Any land area susceptible to being inundated by water from any source. 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.
26. Floodplain administrator. The individual appointed to administer and enforce the floodplain management regulations. Unless otherwise stated, the town engineer is the floodplain administrator.
27. Floodplain board. The council, at such times as they are engaged in the enforcement of this chapter, which is empowered to adopt and implement regulations to provide for the public health, safety and general welfare of the citizens of the town.
28. Floodplain management. The operation of an overall program of corrective and preventive measures for reducing flood damage and preserving and enhancing where possible natural resources in the floodplain, including but not limited to emergency preparedness plans, flood control works and floodplain management regulations.
29. Floodplain management regulations. This chapter and other chapters (zoning. grading. stormwater, etc.), subdivision regulations, subdivision street standards, building codes, health regulations, special purpose ordinances, 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.
30. Floodplain variance. A grant of relief from the requirements of this chapter which permits construction or other uses of property in a manner that would otherwise be prohibited by this chapter.
31. Floodproofing. Any combination of structural and non-structural additions, changes or adjustments to non-residential 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.
32. Flood-related erosion. 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.
33. Floodway. 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.”
34. Floodway fringe. That area of the floodplain on either side of the “regulatory floodway” where encroachment may occur.
35. Functionally dependent use. 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.
36. Governing body. The council of the town of Marana, Arizona.
37. Hardship. Related to section 17-15-11 (floodplain variance procedure) of this chapter, means the exceptional hardship which would result from a failure to grant the requested floodplain variance. The floodplain board 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.
38. Highest adjacent grade. The highest natural elevation of the ground surface prior to construction adjacent to the proposed walls of a structure.
39. Historic structure. Any structure that is:
a. 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;
b. 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;
c. Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the secretary; or
d. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:
i. by an approved state program as determined by the secretary; or
ii. directly by the secretary in states without approved programs.
40. Levee. A man-made structure designed and constructed in accordance with sound engineering practices to contain, control or divert the flow of water so as to provide protection from temporary flooding.
41. Locally regulated floodplain. Floodplains in the town associated with washes and/or sheet flow areas having a base flood discharge of 50 cfs or more.
42. Lowest floor. 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 non-elevation design requirements of this chapter.
43. Manufactured home. See definition in section 17-1-6(A)(119).
44. Manufactured home park or subdivision. A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for sale or rent.
45. Market value. 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. 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.
46. Mean sea level. For purposes of the national flood insurance program, the NGVD or NAVD, to which base flood elevations shown on a community’s FIRM are referenced.
47. 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 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.
48. New manufactured home park or subdivision. A manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets and either final site grading or the pouring of concrete pads) is completed on or after the effective date of floodplain management regulations adopted by the community.
49. 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.
50. One-hundred year flood (100-year flood). A common name for the flood having a one percent chance of being equaled or exceeded in any given year. (See “base flood” definition)
51. Recreational vehicle. A vehicle that is:
a. Built on a single chassis;
b. 400 square feet or less when measured at the largest horizontal projection;
c. Designed to be self-propelled or permanently towable 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.
52. Regulatory flood elevation. 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.
53. Regulatory floodplain. An area associated with a watercourse, including its channel, or any other floodplain or floodprone area that would be inundated by the Base Flood, including all Base Floods where the 100-year peak discharge is 50 cfs or greater.
54. Regulatory floodway. (See “floodway” definition)
55. Repetitive loss structure. A structure covered by a contract for flood insurance issued pursuant to the FIA that has incurred flood-related damage on two occasions during any ten year period ending on the date of the event for which a second claim is made, in which the cost of repairing the flood damage, on average, equaled or exceeded 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.
56. Retention. 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.
57. Riverine. Relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.
58. Sheet flow area. (See “area of shallow flooding” definition)
59. Special flood hazard area (SFHA). An area defined by FEMA within a community subject to a one percent or greater chance of flooding in any given year (base flood). These areas are designated as Zone A, AO, AH and AE on the FIRMs, and other areas determined by the criteria adopted by the director of ADWR.
60. 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 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.
61. Structure. 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.
62. Substantial damage. 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% of the market value of the structure before the damage occurred. Substantial damage also means flood-related damage sustained by a structure on two separate occasions during a rolling ten-year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds 25% of the market value of the structure before the damage occurred.
63. Substantial improvement. Any reconstruction, rehabilitation, addition or other improvement of a structure, the cost of which equals or exceeds 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 would not preclude the structure’s continued designation as a “historic structure”.
64. Variance. See "Floodplain variance."
65. Violation. 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 chapter is presumed to be in violation until that documentation is provided.
66. Water surface elevation. The height, in relation to the NGVD, NAVD, or other datum of floods of various magnitudes and frequencies in the floodplains of riverine and ponding areas. See also base flood elevation.
67. Watercourse. 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).
Ordinance 2022.006 amended Section 17-15-2.
Ordinance 2024.011 adopted revisions proposed by Resolution 2024-031 which amended 17-15-2, paragraph A.16, and paragraphs B.1. and B. 43.