This chapter adopts the set of comprehensive land use regulations attached as appendix A to the ordinance codified herein for the identified 100-year floodplains within the city of Lewistown. Identification of the 100-year floodplain is based on the flood insurance study and the accompanying digital flood insurance rate maps for the city of Lewistown, Montana, dated February 22, 2010. All other ordinances are hereby repealed to the extent of any inconsistencies. (Ord. 1729, 6-21-2010, eff. 7-22-2010)

The purpose of these regulations is to promote the public health, safety and general well being; to minimize flood losses in areas subject to flood hazards; and to promote wise use of the floodplain. These regulations have been established with the following purposes intended:

   (A)   To guide development of the 100-year floodplain areas of the city consistent with the enumerated findings by:

      1.   Recognizing the right and need of watercourses to periodically carry more than the normal flow of water.

      2.   Participating in coordinating efforts of federal, state and local management activities for 100-year floodplains.

      3.   Ensuring the regulations and minimum standards adopted, insofar as possible, balance the greatest public good with the least private injury.

   (B)   Specifically it is the purpose of these regulations to:

      1.   Restrict or prohibit uses which are dangerous to health, safety or property in times of flood or cause increased flood heights or velocities.

      2.   Require that uses vulnerable to floods, including public facilities which serve such uses, be provided with flood protection at the time of initial construction.

      3.   Utilize information which identifies lands which are unsuited for certain development purposes because of flood hazards.

      4.   Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public.

      5.   Ensure that potential buyers are notified that property is within a 100-year floodplain and subject to the provisions of these regulations.

      6.   Ensure that those who occupy 100-year floodplain assume responsibility for their actions. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

Unless specifically defined below, words or phrases used in these regulations shall be interpreted in terms of common usage and to facilitate reasonable application of the regulations:

ALTERATION: Any change or addition to a structure that increases its external dimensions.

APPEAL: A request for a review of the interpretation of the floodplain administrator of any provision of these regulations or a request for a variance.

AREA OF SPECIAL FLOOD HAZARD: The land in the floodplain within the community subject to inundation by a one percent (1%) or greater chance of flood in any given year, i.e., the 100-year floodplain.

ARTIFICIAL OBSTRUCTION DEVELOPMENT: Any obstruction which is not natural and includes any dam, diversion, wall, riprap, embankment, levee, dike, pile, abutment, projection, revetment, excavation, channel rectification, bridge, conduit, culvert, building, refuse, automobile body, fill or other analogous structure matter in, along, across or projecting into any 100-year floodplain which may impede, retard or alter the pattern of flow of water, either in itself or by catching or collecting debris carried by the water, or that is placed where the natural flow of water would carry the same downstream to the damage or detriment of either life or property.

BASE FLOOD: A flood having a one percent (1%) chance of being equaled or exceeded in any given year.

CHANNELIZATION PROJECT: The excavation and/or construction of an artificial channel for the purpose of diverting the entire flow of a stream from its established course.

CRITICAL FEATURE: An integral and readily identifiable part of a flood protection system without which the flood protection provided by the entire system would be compromised.

ESTABLISH: To construct, place, insert or excavate.

FLOOD INSURANCE RATE MAP: The map on which the federal insurance administration has delineated both the 100-year floodplains and the risk premium zones.

FLOOD INSURANCE STUDY: The report in which the federal insurance administration has provided flood profiles, as well as the flood boundary and floodway map and water surface profiles.

FLOOD OR FLOODING: A general and temporary condition of partial or complete inundation of expected dry lands from the overflow of a stream, or the unusual and rapid accumulation or runoff of surface waters from any source.

FLOODPLAIN: The areas adjoining a stream which would be covered by floodwater.

FLOODWAY: The channel of a stream and the adjacent overbank areas that must be reserved in order to discharge a base flood without cumulatively increasing the water surface elevation more than six inches (6").

FLOODWAY FRINGE: That portion of the floodplain outside the limits of the floodway.

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 and port facilities that are necessary for the loading and unloading of cargo or passengers, and shipbuilding/ship repair facilities; it does not include long term storage or related manufacturing facilities.

LEVEE: A manmade structure, usually an earthen embankment, 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.

LEVEE SYSTEM: A flood protection system which consists of a levee or levees and associated structures, such as closure and drainage devices, which are constructed and operated in accordance with sound engineering practices.

LOWEST FLOOR ELEVATION: The lowest floor of the lowest enclosed area that could be converted to a use for living purposes, storage or recreation (including basements). An unfinished or flood resistant enclosure, usable solely for parking of vehicles or building access, 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: 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 connected to the required utilities. For floodplain management purposes, the term "manufactured home" also includes park trailers, travel trailers and other similar vehicles placed on a site for greater than one hundred eighty (180) consecutive days. For insurance purposes, the term "manufactured home" does not include park trailers, travel trailers or other similar vehicles.

MANUFACTURED HOME PARK OR SUBDIVISION: A parcel or contiguous parcels of land divided into two (2) or more manufactured home lots for rent or sale.

MEAN SEA LEVEL: For purposes of the national flood insurance program, the national geodetic vertical datum (NGVD) of 1929 or other datum to which base flood elevations shown on a community's flood insurance rate map are referenced.

NEW CONSTRUCTION: Structures for which the start of construction, substantial improvements or alteration commences on or after the effective date of these regulations.

NONCONFORMING USE: A land use not in accordance with these regulations.

OFFICIAL FLOODPLAIN MAPS: The digital flood insurance rate maps provided by FEMA for the city of Lewistown, dated February 22, 2010.

PERMIT ISSUING AUTHORITY: Lewistown city commission.

REMEDY A VIOLATION: 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 damage, implementing the enforcement provisions of this title, or otherwise deterring future similar violations, or reducing federal financial exposure with regard to the structure or other development.

RIPRAP: Stone, rocks, concrete blocks or analogous material placed along the banks or beds of a stream for the purpose of alleviating erosion.

START OF CONSTRUCTION: Refers to the first placement of permanent construction of a structure on a site, such as the pouring of slabs 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.

STRUCTURE: A walled and roofed building, manufactured home or liquid storage tank that is principally aboveground.

SUBSTANTIAL IMPROVEMENT: Any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds fifty percent (50%) of the current market value of the structure either:

   (A)   Before the improvement or repair is started; or

   (B)   If the structure has been damaged, and is being restored, before the damage occurred.

For the purposes of this definition, substantial improvement is considered to occur when the first construction to any wall, ceiling, floor or other structural part of the building commences. A substantial improvement differs from the alteration of a structure in that it is not defined to include increasing or affecting the external dimensions of the structure. The term also does not include:

   (A)   Any project for improvement of a structure to comply with existing state or local health, sanitary or safety code specifications which are solely necessary to assure safe living conditions; or

   (B)   Any alteration of a structure listed on the national register of historic places or state inventory of historic places.

SUITABLE FILL: Fill material which is stable, compacted, well graded, pervious, generally unaffected by water and frost, devoid of trash or similar foreign matter, and tree stumps or other organic materials; and is appropriate for the purpose of supporting the intended use and/or permanent structure.

VARIANCE: An exception granted from the requirements of these regulations which would permit construction in a manner that would otherwise be prohibited by these regulations.

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 section 60.3 (6)(5), (c)(4), (c)(10), (d)(3), (e)(2), (e)(4), or (e)(5) is presumed to be in violation until such time as that documentation is provided (44 CFR).

WATER SURFACE ELEVATION: The height, in relation to the national geodetic vertical datum (NGVD) of 1929 (or other datum where specified), of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas. (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000; Ord. 1729, 6-21-2010, eff. 7-22-2010)

These regulations shall apply to all lands within the jurisdiction of the city shown on the official floodplain maps as being located within a 100-year floodplain district. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

The floodplain districts established are defined by the base flood elevations and 100-year floodplains as delineated in the flood insurance study. The basis for the flood insurance study is a scientific and engineering report entitled, "The Flood Insurance Study For Fergus County, Montana", dated February 22, 2010, with accompanying digital flood insurance rate maps. The official floodplain maps, together with the flood insurance study are on file in the office of the floodplain administrator. (Ord. 1729, 6-21-2010, eff. 7-22-2010)

The city floodplain administrator has been designated to be the city-county planning director, or such other person as designated by the city manager, with approval of the city commission. The responsibilities of this position are outlined in section 11-12-14 of this chapter. (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1663, 1-3-2000; Ord. 1664, 1-3-2000)

The boundaries of the 100-year floodplain and floodway shall be determined by scaling distances on the official floodplain maps. Where there appears to be a conflict between a mapped floodplain boundary and actual field conditions, the city floodplain administrator may determine that the area is not to be included within the 100-year floodplain. Consequently, the property owner or developer would not have to satisfy the provisions of these regulations. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

In their interpretation and application, the provisions of these regulations shall be held to be minimum requirements and shall be liberally construed in favor of the governing body and shall not be deemed a limitation or repeal of any other powers granted by state statute. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

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 established by the Montana department of natural resources and conservation and the national flood insurance program regulations. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

It is not intended by these regulations to repeal, abrogate or impair any existing easements, covenants, deed restrictions or zoning. However, where these regulations impose greater restrictions, the provisions of these regulations shall prevail. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

These regulations do not imply that areas outside the delineated floodplain boundaries or permitted land uses within such areas will always be free from flooding or flood damages. These regulations shall not create a liability on the part of, or cause action against, the city or any officer or employee thereof for any flood damages that may result from reliance upon these regulations. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

If any section, clause, provision or portion of these regulations is adjudged unconstitutional or invalid by a court of competent jurisdiction, the remainder of these regulations shall not be affected. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

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 regulations. Upon resale of property, the lending institution must notify potential buyers ten (10) days prior to closing that the property is located within a special flood hazard area. The lender must also notify potential buyers whether, in the event of a flood disaster, federal disaster relief would be available to the property. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   As provided in section 11-12-6 of this chapter, the city floodplain administrator has been designated by the city commission, and has the responsibility of such position as outlined in these regulations. (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000)

   (B)   The floodplain administrator is hereby appointed with the authority to review floodplain development permit applications and proposed uses or construction to determine compliance with these regulations, and is required to assure all necessary permits have been received from those governmental agencies from which approval is required by federal and state law and local codes, including section 404 of the federal water pollution control act of 1972, 33 USC 1334.

      1.   Additional Factors: Floodplain development permits shall be granted or denied by the floodplain administrator on the basis of whether the proposed establishment, alteration or substantial improvement of an artificial obstruction or nonconforming use meets the requirements of these regulations. Additional factors that shall be considered for every permit application are:

         (a)   The danger to life and property due to increased flood heights, increased floodwater velocities, or alterations in the pattern of flood flow caused by encroachments.

         (b)   The danger that materials may be swept into other lands or downstream to the injury of others.

         (c)   The proposed water supply and sanitation systems and the ability of these systems to prevent disease, contamination and unsanitary conditions.

         (d)   The susceptibility of the proposed structure and its contents to flood damage and the effects of such damage on the individual owner.

         (e)   The importance of the services provided by the structure to the community.

         (f)   The requirement of the structure for a waterfront location.

         (g)   The availability of alternative locations not subject to flooding for the proposed use.

         (h)   The compatibility of the proposed use with existing development and anticipated development in the foreseeable future.

         (i)   The relationship of the proposed use to the comprehensive plan and floodplain management for the area.

         (j)   The safety of access to property in times of flooding for ordinary and emergency services.

         (k)   Such other factors as are in harmony with the purpose of these regulations, the Montana floodplain and floodway management act, and the national flood insurance program.

   (C)   Within sixty (60) days of receipt of a floodplain development permit application, the floodplain administrator will notify the applicant that the permit is approved, denied, conditionally approved or additional information is required.

   (D)   The floodplain administrator shall adopt such administrative procedures as may be necessary to efficiently administer the provision of these regulations.

   (E)   The floodplain administrator shall maintain such files and records as may be necessary to document nonconforming uses, flood elevations, fee receipts, the issuance of permits, agendas, minutes, records of public meetings, and any other matters related to floodplain management in the city. These files and records will be available for public review. In matters of litigation, the city attorney may restrict access to specific records.

   (F)   Copies of all permits granted must be sent to the department of natural resources and conservation in Helena, Montana.

   (G)   In riverine situations, notification by the floodplain administrator must be made to adjacent communities, the floodplain management section (DNRC), and the federal insurance administration prior to any alteration or relocation of a stream. The flood carrying capacity within the altered or relocated portion of any stream must be maintained. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   Activities or uses which require the issuance of a permit, including the expansion or alteration of such uses, shall not be initiated, established or undertaken until a permit has been issued by the floodplain administrator.

   (B)   Applicants may be required to furnish the following information deemed necessary by the floodplain administrator for determining the suitability of the particular site for the proposed use:

      1.   Plans in duplicate, drawn to scale, with dimensions shown, showing the nature, location and elevation of the lot; existing and proposed structure locations; fill, storage or materials sites; floodproofing measures; first floor of proposed structures in mean sea level elevation; location of the channel; and a description of how the watercourse will be altered.

      2.   A plan of the proposed development indicating external dimensions of structures, street or road finished grade elevations, well locations, individual sewage treatment and disposal sites, excavation and/or fill quantity estimates, site plan and/or construction plans; and

      3.   Specifications for floodproofing, filling, excavating, grading, riprapping, storing materials and utilities location.

   (C)   Applicants who have received permits are required to furnish the following, at the time of an on site conformance inspection, for determining that the permit specifications and conditions have been complied with:

      1.   Certification by a registered professional engineer or licensed surveyor of the actual mean sea level elevation of the lowest floor (including basement) of all new, altered or substantially improved structures.

      2.   If floodproofing techniques were utilized for the above described structures, then the mean sea level elevation to which the floodproofing was accomplished must be similarly certified. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   Emergency repair to and/or replacement of severely damaged public transportation facilities, public water and sewer facilities, and flood control works may be authorized and floodplain development permit requirements waived if:

      1.   Upon notification and prior to the emergency repair and/or replacement, the floodplain administrator determines that an emergency condition warranting immediate action exists; and

      2.   The floodplain administrator agrees upon the nature and type of proposed emergency repair and/or replacement.

   (B)   Authorization to undertake emergency repair and/or replacement work may be given verbally if the floodplain administrator feels that such a written authorization would unduly delay the emergency works. Such verbal authorization must be followed by a written authorization stating the emergency condition, the type of emergency work agreed upon, and a notation that a verbal authorization had been previously given. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   The city-county planning board will act in an advisory capacity to the city commission.

   (B)   The city commission may, by variance, grant a permit that is not in compliance with the minimum standards contained in these regulations according to the following procedures: (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000)

      1.   Variances shall not be issued for areas within a floodway if any increase in flood elevation or velocities would result;

      2.   Variances shall only be issued upon:

         (a)   A determination that refusal of a permit would, because of exceptional circumstances, cause a unique or undue hardship on the applicant or community involved; economic conditions will not constitute hardship.

         (b)   A determination that the granting of a variance will not result in increased flood heights, present additional threats to public safety, be an extraordinary public expense, create nuisances, fraud on or victimization of the public, conflict with existing state or local laws.

         (c)   A determination that a proposed use would be adequately floodproofed.

         (d)   A determination that a reasonable alternative location outside the floodplain is not available.

         (e)   A determination that the variance requested is the minimum necessary, considering the flood hazard, to afford relief. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

         (f)   Approval of the Montana department of natural resources and conservation, upon request from the city commission, prior to formally approving any permit application which is in variation to these regulations;

      3.   Variances shall be issued in writing from the city commission and shall notify the applicant that: (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000)

         (a)   A specific variance is granted, and that certain conditions may be attached.

         (b)   The issuance of a variance to construct a structure below the 100-year floodplain elevation will result in increased premium rates for flood insurance up to amounts as high as twenty five dollars ($25.00) for one hundred dollars ($100.00) of insurance coverage.

         (c)   Such construction below the 100-year flood elevation increases risks of life and property. The floodplain administrator shall maintain the records of variance notification and actions, including justification for their issuance, and forward copies of all variance actions to the Montana department of natural resources and conservation. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (C)   Appeals of any decision of the city commission or its officers or agencies may be taken by an aggrieved person, jointly or separately, to a court of record. (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000)

Any use, arrangement or construction not in compliance with that authorized shall be deemed a violation of these regulations and punishable as provided in section 11-12-20 of this chapter. An applicant may be required to submit certification by a registered professional engineer, architect or other qualified person designated by the floodplain administrator that finished fill and building floor elevations, floodproofing or other flood protection measures were accomplished in compliance with these regulations. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

The floodplain administrator shall bring any violation of these regulations to the attention of the city commission, the city attorney, and the Montana department of natural resources and conservation. (Ord. 1576, 5-1-1989, eff. 6-15-1989; amd. Ord. 1664, 1-3-2000)

Violation of the provisions of these regulations or failure to comply with any of the requirements, including permit approval prior to development of flood prone lands and conditions and safeguards established in connection with variances, shall constitute a misdemeanor. Any person who violates these regulations or fails to comply with any of its requirements shall, upon conviction thereof, be fined not more than one hundred dollars ($100.00) or be imprisoned in jail for not more than ten (10) days or be both fined and imprisoned. Each days continuance of a violation shall be deemed a separate and distinct offense. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

A processing fee of thirty five dollars ($35.00) shall be submitted with each permit application. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

The minimum floodplain development standards listed in this chapter apply to the floodway/floodway fringe portions of the 100-year floodplain as delineated on the city floodway and flood boundary maps, and also correspond to the numbered A zones depicted on the city flood insurance rate maps. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   Uses Allowed Without Permits: The following open space uses shall be allowed without a permit anywhere within the floodway, provided that such uses 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.   Private and public recreational areas, 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.

      3.   Forestry, including processing of forest products with portable equipment.

      4.   Residential uses such as lawns, gardens, parking areas and play areas.

      5.   Irrigation and livestock supply wells; provided that they are located at least five hundred feet (500') from domestic water supply wells.

      6.   Fences, except permanent fences crossing channels.

   (B)   Uses Requiring Permits: The following artificial obstructions and nonconforming uses may be permitted in the floodway subject to the issuance of a permit by the floodplain administrator:

      1.   Loading or parking areas or emergency landing strips associated with industrial-commercial facilities.

      2.   Excavation of material from the pits and pools provided that:

         (a)   A buffer strip of undisturbed land of sufficient width to prevent flood flows from channeling into the excavation is left between the edge of the channel and the edge of the excavation.

         (b)   The excavation meets all applicable laws and regulations of other local and state agencies.

         (c)   Excavated material is stockpiled outside the floodway.

      3.   Railroad, highway and street stream crossings, provided the crossings are designed to offer minimal obstruction to flood flow.

      4.   Limited filling for highway, street and railroad embankments not associated with stream crossings; provided, that:

         (a)   Reasonable alternative transportation routes outside the designated floodway are not available.

         (b)   Such floodway encroachment is located as far from the stream channel as possible.

      5.   Buried or suspended utility transmission lines; provided that:

         (a)   Suspended utility transmission lines are designed such that the lowest point of the suspended lines is at least six feet (6') higher than the elevation of the 100-year frequency.

         (b)   Towers and other appurtenant structures are designed and placed to withstand and offer minimal obstruction to flood flows.

         (c)   Utility transmission lines carrying toxic or flammable materials are buried to a depth at least twice the calculated maximum depth of scour for a flood of 100-year frequency. The maximum depth of scour may be determined from any of the accepted hydraulic engineering methods, but the final calculated figure shall be subject to approval by the floodplain administrator.

      6.   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 of downstream movement.

         (b)   The material or equipment is readily removable within the limited time available after flood warning. Storage of flammable, toxic or explosive materials shall not be permitted.

      7.   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 (25') 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 of the submersible type or are adequately floodproofed.

         (e)   Check valves are installed on main water lines at wells and all building entry locations.

      8.   Buried and sealed vaults for sewage disposal in recreational areas; provided, that they meet applicable laws and standards administered by the Montana department of health and environmental sciences.

      9.   Public or private campgrounds; provided that:

         (a)   Access roads require only limited fill and do not obstruct or divert floodwaters.

         (b)   No dwellings are allowed.

      10.   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 low flood damage potential.

         (c)   The structures will, insofar as possible, be located on higher ground than the surrounding ground and as far from the channel as possible.

         (d)   The floodproofing standards of section 11-12-27 of this chapter are met.

         (e)   The structure will be constructed and placed so as to offer a minimal obstruction to flood flows and is anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads.

      11.   Substantial improvements to any structure provided that the provisions of subsections 11-12-24(B)3 and (B)4 of this chapter are met.

      12.   All other artificial obstructions, substantial improvements, or nonconforming uses not specifically listed in, or prohibited by, this chapter.

   (C)   Permits For Flood Control Works: Flood control works shall be allowed within floodways subject to the issuance of a permit by the floodplain administrator with the following conditions:

      1.   Levees and floodwalls are permitted if:

         (a)   The proposed levee or floodwall is designed and constructed to safely convey a flood of 100-year frequency.

         (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 frequency. The floodplain administrator may establish either a lower or higher permissible increase in the elevation of the flood of 100-year frequency for individual levee projects, with concurrence of the Montana department of natural resources and conservation and the federal insurance administration based upon the following criteria:

            (1)   The estimated cumulative effect of other reasonable anticipated future permissible uses.

            (2)   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 only, are constructed at least three feet (3') higher than the elevation of a flood of 100-year frequency.

      2.   Riprap, except that which is hand placed, if:

         (a)   The riprap is designed to withstand a flood of 100-year frequency.

         (b)   The riprap does not increase the elevation of the flood of 100-year frequency.

         (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 flood of 100-year frequency in the proximity of the project.

      4.   Dams; provided that:

         (a)   They are designed and constructed in accordance with approved safety standards.

         (b)   They will not increase flood hazards downstream, either through operational procedures or improper hydrologic design.

   (D)   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 increase the upstream elevation of the flood of 100-year frequency.

      2.   The proposed diversion is not designed and constructed to minimize potential erosion from a flood of 100-year frequency.

      3.   Any permanent diversion structure crossing the full width of the stream channel is not designed and constructed to safely withstand a flood of 100-year frequency.

   (E)   Prohibited Uses: The following artificial obstructions and nonconforming uses are prohibited within the floodway:

      1.   Encroachments, including fill, new construction, substantial improvements and other development within the adopted regulatory floodway that would result in erosion of embankment, obstruction of the natural flow of waters, or increase in flood levels within the community during the occurrence of the flood of 100-year frequency; additionally, manufactured homes.

      2.   The construction or permanent storage of an object subject to flotation or movement during flood level periods.

      3.   Solid waste disposal, water distribution systems and sewage treatment and/or disposal systems, except as allowed or approved under the laws and standards administered by the Montana department of health and environmental sciences.

      4.   Storage of highly toxic, flammable or explosive materials. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   Uses Allowed Without Permits: All uses allowed in the floodway, according to the provisions of subsection 11-12-23(A) of this chapter, shall also be allowed without a permit in the floodway fringe.

   (B)   Uses Requiring Permits: All uses allowed in the floodway subject to the issuance of a permit, according to the provisions of subsections 11-12-23(B) and (C) of this chapter, shall also be allowed by permit within the floodway fringe. In addition, new construction, substantial improvements and alterations to structures, including, but not limited to, residential, commercial and industrial construction and suitable fill shall be allowed by permit from the floodplain administrator 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.

      3.   The new construction, alterations and substantial improvements of residential structures must be constructed on suitable fill such that bottom floor elevations (including basement) are two feet (2') or more above the elevation of the flood of 100-year frequency. The suitable fill shall be at elevation no lower than the elevation of the flood of 100-year frequency and shall extend for at least fifteen feet (15'), at that elevation, beyond the structures in all directions.

      4.   The new construction, alteration and substantial improvement of commercial and industrial structures must be either constructed on suitable fill, as specified in subsection (B)(3) of this section, or be adequately floodproofed to an elevation two feet (2') above the elevation of the flood of 100-year frequency. Floodproofing shall be accomplished in accordance with section 11-12-27 of this chapter and shall further include impermeable membranes or materials for floors and walls; watertight enclosures for all windows, doors and other openings; and be certified by a registered professional engineer or architect that the floodproofing methods are adequate to withstand the floor depths, pressures, velocities, impact and uplift forces associated with the flood of 100-year frequency.

      5.   For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwater. Design for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:

         (a)   A minimum of two (2) openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.

         (b)   The bottom of all openings shall be no higher than one foot (1') above grade. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

      6.   A development proposed for 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 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:

         (a)   A hydraulic study documenting probable effect on upstream or downstream property owners caused by the proposed development; or

         (b)   The calculated increase in the 100-year frequency water surface profile caused by the proposed development.

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 equivalent to a minimum of six inches (6"), unless existing or anticipated development in the area dictates a lesser value of allowable increase.

Also, 100-year water surface profile data shall be provided for subdivision proposals and other proposed developments that contain greater than fifty (50) lots or five (5) acres, whichever is less, including manufactured home parks and subdivisions.

      7.   Manufactured homes shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is located two feet (2') above the elevation of the 100-year flood.

      8.   All manufactured homes to be placed or substantially improved within the floodway shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is located at or above the base flood elevation and securely anchored to the elevated foundation to resist flotation, collapse, or lateral movement. Anchoring provisions require that:

         (a)   Over the top ties be provided at each of the four (4) corners of the manufactured home, with two (2) additional ties per side at intermediate locations. Manufactured homes less than fifty feet (50') long require one additional tie per side.

         (b)   Frame ties be provided at each corner of the home with five (5) additional ties per side at intermediate points. Manufactured homes less than fifty feet (50') long require four (4) additional ties per side.

         (c)   All components of the anchoring system be capable of carrying a force of four thousand eight hundred (4,800) pounds.

         (d)   Any additions to the manufactured home must be similarly anchored.

         (e)   Adequate surface drainage and access for a hauler are provided.

      9.   Manufactured homes proposed for use as a residential, commercial, or industrial structure must meet the anchoring requirements of subsection (B)8 of this section.

      10.   Roads, streets, highways and rail lines shall be designed to minimize increases 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 two feet (2') above the elevation of the flood of 100-year frequency.

      11.   Agricultural structures that have low damage potential, such as sheds, barns, shelters and hay and grain storage structures must be adequately anchored to prevent flotation or collapse.

   (C)   Prohibited Uses: The following artificial obstructions and nonconforming uses are prohibited within the floodway fringe:

      1.   Solid waste disposal, water distribution systems and sewage treatment and/or disposal systems, except as allowed or approved under the laws and standards administered by the Montana department of health and environmental sciences.

      2.   Storage of highly toxic, flammable, or explosive materials. Storage of petroleum products may be allowed by permit if buried in tightly sealed containers or if stored on compacted fill at least two feet (2') above the elevation of the flood of 100-year frequency. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   Shallow Floodplains: Shallow flooding areas are delineated as AO zone floodplains on the city flood insurance rate maps. All the provisions of section 11-12-24, "Floodway Fringe", of this chapter, shall apply to AO zone floodplains. The flooding depth of 100-year frequency is indicated as the depth number on the flood insurance rate maps and shall be referenced to the crown of the nearest street or stream flow line in determining fill and/or floodproofing heights which are to be utilized in applying the provisions of subsections 11-12-24(B)3 and (B)4 of this chapter.

   (B)   Floodplain Boundary Interpretation: The floodplain administrator shall make interpretations where needed as to the exact location of an AO zone floodplain boundary when there appears to be a conflict between a mapped boundary and actual field conditions. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

The minimum floodplain development standards listed in this chapter apply to the 100-year floodplains delineated by approximate methods and identified as unnumbered A zones on the city insurance rate maps.

   (A)   Uses Allowed Without Permits: All uses allowed in a floodway, according to the provisions of subsection 11-12-23(A) of this chapter, shall also be allowed without a permit in the floodway fringe.

   (B)   Uses Requiring Permits: All uses allowed in the floodway fringe subject to the issuance of a permit, according to the provisions of subsection 11-12-24(B) of this chapter, shall require permits from the floodplain administrator for zone A floodplains. Also, the provisions of subsection 11-12-24(B)6 of this chapter apply to the zone A floodplains with no floodway delineated or water surface profile computed. Since there are no 100-year frequency water surface profiles computed for zone A floodplains, the following conditions also shall apply:

      1.   Elevation data on the 100-year frequency flood shall be provided for subdivision proposals and other proposed developments which contain greater than fifty (50) lots or five (5) acres (whichever is less), including manufactured home parks and subdivisions, and used in applying subsections 11-12-24(B)3 and (B)4 of this chapter.

      2.   Obtain, review, and reasonably utilize any 100-year base flood elevation and floodway data available from a federal, state, or other source as criteria for requiring that new construction, substantial improvements, or other development in zone A meet the provisions of subsections 11-12-24(B)3 and (B)4 of this chapter.

      3.   Historical flood elevations may be used by the floodplain administrator in determining suitable fill or floodproofing elevations to be achieved, and used in accordance with subsections 11-12-24(B)3 and (B)4 of this chapter.

      4.   If historical flood evidence is not available, then the floodplain administrator shall determine, from a field review at the proposed development site, an appropriate fill and/or floodproofing elevation to be utilized in applying subsections 11-12-24(B)3 and (B)4 of this chapter.

      5.   Proposed structures must be anchored to prevent flotation or collapse and must be located as far from stream channels as practicable.

   (C)   Prohibited Uses: Those uses prohibited in the floodway fringe, in accordance with subsection 11-12-24(C) of this chapter, shall also be prohibited within the zone A floodplain boundaries.

   (D)   Floodplain Boundary Interpretation: The floodplain administrator shall make interpretations where needed as to the exact location of the zone A floodplain boundary when there appears to be a conflict between a mapped boundary and actual field conditions. (Ord. 1576, 5-1-1989, eff. 6-15-1989)

   (A)   The following floodproofing requirements are to be utilized for a proposed structure, as stipulated by the floodplain administrator in accordance with this chapter, and the methods used must be certified as adequate by a registered professional engineer or architect. The registered professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with the accepted standards for meeting the applicable provisions of this section, and a record of such certificates which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained in the office of the floodplain administrator.

   (B)   Permitted floodproof systems shall conform to the conditions listed herein below:

Electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities shall be located two feet (2') above the base flood elevation or designed to prevent water from entering or accumulating within the components during conditions of flooding.

      1.   Electrical Systems:

         (a)   All incoming power service equipment, including all metering equipment, control centers, transformers, distribution and lighting panels and other stationary equipment must be located two feet (2') above the elevation of the flood of 100-year frequency.

         (b)   Portable or movable electrical equipment may be placed below the elevation of the flood of 100-year frequency, if the equipment be disconnected by a single plug and socket assembly of the submersible type.

         (c)   The main power service line shall have automatically operated electrical disconnect equipment or manually operated electrical disconnect equipment located at an accessible remote location outside the floodplain of 100-year frequency and above the elevation of the flood of 100-year frequency; and

         (d)   All electrical wiring systems installed at or below the flood of 100-year frequency shall be suitable for continuous submergence and may not contain fibrous components.

      2.   Heating Systems:

         (a)   Float operated automatic control valves must be installed in supply lines to gas furnaces so that the fuel supply is automatically shut off when the floodwaters reach the floor level where the furnaces are located.

         (b)   Manually operated gate valves that can be operated from a location above the elevation of the flood of 100-year frequency also shall be provided in gas supply lines.

         (c)   Electric heating systems must be installed in accordance with subsection (B)1 of this section.

      3.   Plumbing Systems:

         (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 such that the lowest point of possible water entry is two feet (2') above the elevation of the flood of 100-year frequency. (Ord. 1576, 5-1-1989, eff. 6-15-1989)