17.56.1.010 Authority

The Montana Floodplain and Floodway Management Act (Title 76, Chapter 5, MCA) authorizes the adoption of this chapter.

17.56.1.020 Applicability

These regulations apply to all land within the special flood hazard areas shown on the flood insurance rate maps as adopted by the Federal Emergency Management Agency (FEMA) on February 15, 2002, and as may be amended. These maps are on file in the office of the floodplain administrator and are available for public inspection. Copies of these maps may be purchased directly from FEMA. (Ord. 2950, 2007)

17.56.1.030 Purpose

This chapter is established to comply with the Montana Floodplain and Floodway Management Act (Title 76, Chapter 5, MCA), ensure compliance with the requirements for the City’s continued participation in the National Flood Insurance Program, and promote the public health, safety, and general welfare. To that end, this chapter is intended to accomplish the following purposes:

1. protect human life and health to the greatest extent possible
2. control land uses and development within the 100-year floodplain
3. minimize flood losses in areas subject to flood hazards
4. promote the wise use of the floodplain
5. recognize the right and need of watercourses to periodically carry more than the normal flow of water
6. ensure the regulations and minimum standards adopted, insofar as possible, balance the greatest public good with the least private injury
7. restrict or prohibit uses which are dangerous to health, safety, and property in times of flood, or that cause increased flood heights and velocities
8. require that uses vulnerable to floods, including public facilities, be provided with flood protection at the time of initial construction or reconstruction
9. identify lands unsuitable for certain development purposes because of flood hazards
10. minimize the need for rescue and relief efforts associated with flooding undertaken at the expense of the general public
11. ensure that potential buyers are notified that property is within a 100-year floodplain and subject to the provisions of these regulations
12. ensure that those who occupy 100-year floodplains assume responsibility for their actions
13. limit filling, grading, dredging, and other similar development which may increase erosion, sedimentation, or flood damage

17.56.1.040 Floodplain administrator

1. Appointment. The zoning technician with the Community Development Department is the designated floodplain administrator.
2. Administrative procedures. The floodplain administrator shall adopt such administrative procedures as may be necessary to efficiently administer the provisions of these regulations.
3. Records. The floodplain administrator shall maintain such files and records as may be necessary to document nonconforming uses, base flood elevation, floodproofing and elevation certification, fee receipts, the issuance of permits, agendas, minutes, records of public meetings, and any other matters related to floodplain management in the City of Great Falls. Such files and records shall be open for public inspection.

17.56.1.050 Compliance

No structure or land use shall be located, extended, converted or structurally altered without full compliance with the provisions of these regulations and other applicable regulations. These regulations meet the minimum floodplain development requirements as set forth by the Montana Board of Natural Resources and Conservation and in the National Flood Insurance Program regulations.

17.56.1.060 Warning and disclaimer of liability

These regulations do not imply that areas outside the delineated floodplain boundaries or permitted land uses will always be totally free from flooding or flood damage. These regulations shall not create a liability or cause of action against the City of Great Falls, or any officer or employee thereof, for flood damages that may result from reliance upon these regulations.

17.56.1.070 Disclosure

All owners of property in an identified 100-year floodplain as indicated on the official floodplain maps must notify potential buyers or their agents that such property is subject to the provisions of these and other applicable regulations.

17.56.1.080 Variances

The Board of Adjustment may issue a variance from these standards only in conformance with Chapter 16 of this Title.

17.56.1.090 Voting and quorum

In formulating community development goals, the City shall consider the development of a plan for evacuating residents of all manufactured home parks or subdivisions located within flood prone areas. This plan should be developed, filed with, and approved by appropriate community emergency management authorities.

17.56.2.010 Generally

The minimum floodplain development standards listed in this chapter apply to the floodway and floodway fringe portions of the 100-year floodplain as delineated on the flood boundary-floodway maps, and also correspond to the numbered A or AE Zones depicted on the flood insurance rate maps.

17.56.2.020 Floodway

1. Uses allowed without a permit. The following open space uses shall be allowed without a permit within the floodway, provided that such uses conform to the provisions of Article 3 of this chapter, are not prohibited by any other ordinance, resolution or statute and do not require fill, excavation, permanent storage of materials, or equipment or structures other than portable structures;
   1. agricultural uses;
   2. accessory uses such as loading and parking areas, or emergency land strips associated with industrial and commercial facilities;
   3. private and public recreational uses such as golf courses, driving ranges, archery ranges, picnic grounds, boat launching ramps, parks, wildlife management and natural areas, game farms, fish hatcheries, shooting preserves, target ranges, trap and skeet ranges, hunting and fishing areas, and hiking or horseback riding trails;
   4. forestry, including processing of forest products with portable equipment;
   5. residential uses such as lawns, gardens, parking areas, and play areas;
   6. irrigation and livestock supply wells, provided that they are located at least five hundred feet from domestic water supply wells;
   7. fences, except permanent fences crossing channels; and
   8. recreational vehicles provided that they be on the site for fewer than one hundred eighty consecutive days or be fully licensed and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jacking system with wheels intact, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions.
2. Uses requiring a permit. The following may be permitted in the floodway subject to the issuance of a permit by the floodplain administrator, and subject to all other applicable laws and regulations of other local and State agencies:
   1. excavation of material from pits and pools, provided that: (a) a buffer strip of undisturbed land is left between the edge of the channel and the edge of the excavation of sufficient width to prevent flood flows from channeling into the excavation; (b) the excavation meets all applicable laws and regulations of other local and State agencies; and (c) excavated material is stockpiled outside the floodway;
   2. railroad, highways, and street stream crossings, provided the crossings are designed to offer minimal obstruction to flood flow. Stream crossings shall not increase elevation of the 100-year flood more than one-half foot nor cause a significant increase in flood velocities;
   3. limited filling for highway, street, and railroad embankments not associated with stream crossings, provided that: (a) reasonable alternate transportation routes outside the designated floodway are not available; and (b) such floodway encroachment is located as far from the stream channel as possible and shall not result in a cumulative increase in base flood elevations, after allowable encroachments into the floodway fringe, exceeding one-half foot;
   4. buried or suspended utility transmission lines, provided that: (a) suspended utility transmission lines are designed so the lowest point of the suspended line is at least 6 feet higher than the elevation of the 100-year flood; (b) towers and other appurtenance structures are designed and placed to withstand and minimally obstruct flood flows; and (c) utility transmission lines carrying toxic or flammable materials are buried to a depth of at least twice the calculated maximum depth of scour for a 100-year flood. The maximum depth of scour shall be determined by hydraulic engineering methods, acceptable to the floodplain administrator.
   5. storage of materials and equipment, provided that: (a) the material or equipment is not subject to major damage by flooding and is properly anchored to prevent flotation or downstream movement; or (b) the material or equipment is readily moveable within the limited time available after flood warning. Storage of flammable, toxic, or explosive materials shall not be permitted.
   6. domestic water supply wells, provided that: (a) they are driven or drilled wells located on ground higher than the surrounding ground to assure positive drainage from the well; (b) well casings are watertight to a distance of at least twenty-five feet below the ground surface; (c) water supply and electrical lines have a watertight seal where the lines enter the casing; (d) all pumps, electrical lines and equipment are either submersible or adequately floodproofed; and (e) check valves are installed on main water lines at wells and at all building entry locations;
   7. buried and sealed vaults for sewage disposal in recreational areas, provided they meet applicable laws and standards administered by the Montana Department of Health and Environmental Sciences;
   8. public and private campgrounds, provided that: (a) access roads require only limited fill and do not obstruct or divert floodwaters; and (b) recreational vehicles and travel trailers are licensed and ready for highway use (i.e., They are ready for highway use if on wheels or jacking system with wheels intact, are attached to the site with only quick disconnect type utilities and securing devices, and have no permanently attached additions).
   9. structures accessory to the uses permitted in this section such as boat docks, marinas, sheds, picnic shelters, tables and toilets, provided that: (a) the structures are not intended for human habitation; (b) the structures will have a low flood damage potential; (c) the structures will, insofar as possible, be located on ground higher than the surrounding ground and as far from the channel as possible; (d) the floodproofing standards of this chapter are met; and (e) the structures will be constructed and placed so as to offer minimal obstruction to flood flows and are anchored to prevent flotation;
   10. substantial improvements to any structure, provided that the provisions of subsections (B)(3) and (B)(4) of Section 17.56.2.030 of this chapter are met. In the floodway the structure must be floodproofed or elevated on a permanent foundation rather than on fill.
   11. all other artificial obstructions, substantial improvements, or nonconforming uses not specifically listed or prohibited by these regulations.
3. Permits for flood control works. Flood control works shall be allowed within floodways subject to the issuance of a permit by the floodplain administrator, and subject to all other applicable laws and regulations of other local and State agencies, with the following conditions:
   1. levees and floodwalls provided: (a) the proposed levee or floodwall is designed and constructed to safely convey a 100-year flood, and (b) the cumulative effect of the levee or floodwall combined with allowable floodway fringe encroachments does not increase the unobstructed elevation of the 100-year flood more than one-half foot. The floodplain administrator may establish either a lower or higher permissible increase in the elevation of the 100-year flood for individual levee projects. Any change must be in concurrence with the Montana Department of Natural Resources and Conservation and the Federal Emergency Management Agency based upon consideration of the following criteria: (i) the estimated cumulative effect of any anticipated future reasonable permissible uses, and (ii) the type and amount of existing flood-prone development in the affected area, (c) the proposed levee or floodwall, except those to protect agricultural land, are constructed at least 3 feet higher than the elevation of a 100-year flood;
   2. riprap, except that which is hand-laced, if: (a) the riprap is designed to withstand a 100-year flood; (b) the riprap does not increase the elevation of the 100-year flood; and (c) the riprap will not increase erosion upstream, downstream or adjacent to the riprap site;
   3. channelization projects if they do not significantly increase the magnitude, velocity, or elevation of the 100-year flood in the proximity of the project;
   4. dams, provided that: (a) they are designed and constructed in accordance with the Montana Dam Safety Act and applicable safety standards; and (b) they will not increase flood hazards down-stream, either through operational procedures or improper hydrologic design.
4. Permits for water diversions. Permits for the establishment of a water diversion or change in place of diversion shall not be issued if, in the judgment of the floodplain administrator:
   1. the proposed diversion will significantly increase the upstream elevation of the 100-year flood to the detriment of neighboring property;
   2. the proposed diversion is not designed and constructed to minimize potential erosion from a 100-year flood; and
   3. any permanent diversion structure crossing the full width of the stream channel is not designed and constructed to safely withstand up to a 100-year flood.
5. Prohibited uses. The following artificial obstructions and nonconforming uses are prohibited within the floodway:
   1. New construction, substantial improvements and alterations of any residential, commercial or industrial structure;
   2. Encroachments, including fill, new construction, alterations, substantial improvements, and other development within the adopted regulatory floodway that would result in erosion of the embankment, obstruction of the natural flow of waters, or increase in flood levels within the community during the occurrence of the 100-year flood;
   3. The construction or permanent storage of an object subject to flotation or movement during flooding;
   4. Solid waste disposal, sewage treatment, and sewage disposal systems, except as allowed or approved under the laws and standards administered by the Montana Department of Health and Environmental Sciences;
   5. Storage of toxic, flammable, hazardous, or explosive materials;
   6. Alterations of structures unless it can be shown the alteration will not raise flood heights; and
   7. Manufactured homes or replacement of manufactured homes in or out of a manufactured home subdivision or park.

17.56.2.030 Floodway fringe

1. Uses allowed without a permit. All uses allowed without a permit in the floodway shall also be allowed without a permit in the floodway fringe. In addition, individual or multiple family subsurface sewage disposal systems are allowed only when they are reviewed and approved under laws and regulations administered by the Department of Health and Environmental Sciences or the local health board.
2. Uses requiring a permit. All uses allowed in the floodway subject to the issuance of a permit shall also be allowed by permit within the floodway fringe. In addition, new construction, substantial improvements, and alterations to structures are allowed by permit. This includes but is not limited to residential, commercial and industrial construction, and suitable fill to be allowed by permit from the floodplain administrator and subject to the following conditions:
   1. Such structures or fill must not be prohibited by any other statute, regulation, ordinance, or resolution;
   2. Such structures or fill must be compatible with local comprehensive plans and zoning regulations;
   3. The new construction, alterations, and substantial improvements of residential structures including manufactured homes must be constructed on suitable fill such that the lowest floor elevation (including basement) is 2 feet or more above the elevation of the 100-year flood elevation. The suitable fill shall be at an elevation no lower than the elevation of the 100-year flood elevation. The suitable fill shall be at an elevation no lower than the elevation of the 100-year flood and shall extend for at least fifteen feet, at that elevation, beyond the structure(s) in all directions;
   4. The new construction, alteration, and substantial improvement of commercial and industrial structures can be constructed on suitable fill as specified in subparagraph (B)(3) of this section. If not constructed on fill, commercial and industrial structures must be adequately floodproofed to an elevation no lower than 2 feet above the elevation of the 100-year flood. Flood-proofing must be certified by a registered professional engineer or architect that the floodproofing methods are adequate to withstand the flood depths, hydrodynamic and hydrostatic pressures, velocities, impact, buoyancy, and uplift forces associated with the 100-year flood. If the structure is designed to allow internal flooding of the lowest floor, use of the lowest floor shall be limited to parking, loading areas, building access and storage of equipment or materials not appreciably affected by floodwaters. The floors and walls shall be designed and constructed of materials resistant to flooding to an elevation no lower than 2 feet above the 100-year flood elevation. Walls shall be designed to automatically equalize hydrostatic forces by allowing for entry and exit of floodwaters. Openings may be equipped with screens, louvers, valves, other coverings, or devices which permit the automatic entry and exit of floodwaters. Structures whose lowest floors are used for a purpose other than parking, loading, or storage of materials resistant to flooding shall be waterproofed to an elevation lower than two feet above the 100-year flood elevation. Floodproofing shall include impermeable membranes or materials for floors and walls and watertight enclosures for all windows, doors, and other openings. These structures shall be designed to withstand the hydrostatic, hydrodynamic and buoyancy effects of a 100-year flood. Floodproofing shall also be accomplished in accordance with Article 3 of this chapter;
   5. All manufactured homes placed in the floodway fringe must have the chassis securely anchored to a foundation system that will resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, over-the-top or frame ties to ground anchors. The following conditions also apply: (a) When a manufactured home is altered, replaced because of substantial damage as a result of a flood, or replaced on an individual site, the lowest floor must be elevated 2 feet above the base flood elevation. The home can be elevated on fill or raised on a permanent foundation of reinforced concrete, reinforced mortared block, reinforced piers, or other foundation elements of at least equivalent strength. (b) Replacement or substantial improvement of manufactured homes in an existing manufactured home park or subdivision must be raised on a permanent foundation. The lowest floor must be 2 feet above the base flood elevation. The foundation must consist of reinforced concrete, reinforced mortared block, reinforced piers, or other foundation elements of at least equivalent strength. (c) Manufactured homes proposed for use as commercial or industrial structures must be elevated and anchored, rather than floodproofed;
   6. Fill material placed in the floodway fringe must be stable, compacted, well-graded, pervious, generally unaffected by water and frost, devoid of trash or similar foreign matter, devoid of tree stumps or other organic material, and appropriate for the purpose of supporting the intending use and/or permanent structure;
   7. Roads, streets, highways and rail lines shall be designed to minimize increase in flood heights. Where failure or interruption of transportation facilities would result in danger to the public health or safety, the facility shall be located 2 feet above the elevation of the 100-year flood;
   8. Agricultural structures that have a low damage potential, such as sheds, barns, shelters and hay and grain storage structures, must be adequately anchored to prevent flotation or collapse and all electrical facilities shall be placed above the base flood elevation; and
   9. Recreational vehicles, if they are on the site for more than 180 consecutive days or are not ready for highway use, must meet the elevating requirements of subparagraph (B)(3) of this section.
3. Prohibited uses. The following artificial obstructions and nonconforming uses are prohibited within the floodway fringe:
   1. Solid waste disposal, sewage treatment, and sewage disposal systems, except as allowed or approved under the laws and standards administered by the Montana Department of Health and Environmental Sciences; and
   2. Storage of highly toxic, flammable, or explosive materials. Storage or petroleum products may be allowed by permit if buried in tightly sealed impermeable containers or if stored on compacted fill at least 2 feet above the elevation of the 100-year flood and anchored to prevent downstream movement.

17.56.2.040 Floodplain areas with flood elevations and no delineated floodway

1. A development proposed for location within a 100-year floodplain, where water surface elevations are available but no floodway is delineated, may not significantly increase flood velocities or depths or generally alter patterns of flood flow. The provisions of Section 17.56.2.030 shall apply to these areas. The floodplain administrator may require a permit applicant to furnish additional hydraulic data before acting on a permit application for such a floodplain. The data may include, but is not limited to, any of the following:
   1. A hydraulic study documenting probable effects on upstream or downstream property owners caused by the proposed development; or
   2. The calculated increase in the 100-year flood frequency water surface profile caused by the proposed development.
2. Permits for such proposed development may be modified or denied if the additional information shows that the proposed use would cause an additional flood hazard to adjacent property or significantly increase flood heights. A significant increase in flood heights is one-half foot unless existing or anticipated development in the area dictates a lesser amount of allowable increase.

17.56.3.010 Certification

If the following floodproofing requirements are to be applied to a proposed structure, as stipulated by the floodplain administrator in accordance with these regulations, the methods used must be certified as adequate by a registered professional engineer or architect.

17.56.3.020 Conformance

Permitted floodproof systems shall conform to the conditions listed below and the floodproofing standards listed in subsection (B)(4) of Section 17.56.2.030 of these regulations for commercial and industrial structures.

17.56.3.030 Standards

Commercial and industrial buildings that are not elevated 2 feet or more above the 100-year flood elevation shall be floodproofed to an elevation no lower than 2 feet above the elevation of the 100-year flood consistent with the following standards:

1. If the structure is designed to allow internal flooding of the lowest floor, use of the lowest floor shall be limited to parking, loading areas, building access and storage of equipment or materials not appreciably affected by floodwaters. The floors and walls shall be designed and constructed of materials resistant to flooding to an elevation no lower than 2 feet above the 100-year flood elevation. Walls shall be designed to automatically equalize hydrostatic forces by allowing for entry and exit of floodwaters. Openings may be equipped with screens, louvers, valves, other coverings, or devices which permit the automatic entry and exit of floodwaters.
2. Structures whose lowest floors are used for a purpose other than parking, loading, or storage of materials resistant to flooding shall be waterproofed to an elevation lower than 2 feet above the 100-year flood elevation. Floodproofing shall include impermeable membranes or materials for floors and walls and watertight enclosures for all windows, doors, and other openings. These structures shall be designed to withstand the hydrostatic, hydrodynamic and buoyancy effects of a 100-year flood.
3. Electrical systems shall meet the following criteria: (a) All incoming power service equipment, including all metering equipment, control centers, transformers, distribution and lighting panels, and all other stationary equipment must be located at least 2 feet above the elevation of the 100-year flood; (b) Portable or moveable electrical equipment may be placed below the elevation of the 100-year flood, if the equipment can be disconnected by a single submersible plug-and-socket assembly; (c) The main power service line shall have automatic or manually operated electrical disconnect equipment located at an accessible location outside the 100-year floodplain and above the elevation of the 100-year flood; and (d) All electrical wiring systems installed at or below the elevations of the 100-year flood shall be suitable for continuous submergence and may not contain fibrous components.
4. Heating systems shall meet the following criteria: (a) Float operated automatic control valves must be installed in gas furnace supply lines so that the fuel supply is automatically shut off when floodwaters reach the floor level where the furnace is located. (b) Manually operated gate valves must be installed in gas supply lines. The gate valves must be operable from a location above the elevation of the 100-year flood. (c) Electric heating systems must be installed in accordance with the standards for electrical systems.
5. Plumbing systems shall meet the following criteria: (a) Sewer lines, except those to be buried and sealed in vaults, must have check valves installed to prevent sewage backup into permitted structures. (b) All toilet stools, sinks, urinals and drains must be located so the lowest point of possible water is at least 2 feet above the elevation of the 100-year flood.