Chapter 17.22 FREQUENTLY FLOODED AREAS – FLOOD HAZARD ZONE (FHZ)

The legislature of the state has delegated the responsibility to local governmental entities to adopt floodplain management regulations designed to promote the public health, safety, and general welfare of its citizenry. Therefore, the city council of Chehalis ordains as set forth in this chapter. [Ord. 1122B § 13, 2025.]

17.22.010 Findings of fact.

A. The flood hazard areas of Chehalis are subject to periodic inundation which may result in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare.

B. These flood losses are caused by climatic conditions and the cumulative effect of natural and manmade obstructions in areas of special flood hazards which increase flood heights and velocities and may damage uses in other areas. Uses that are inadequately floodproofed, elevated or otherwise protected from flood damage also contribute to the flood loss. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.020 Statement of purpose.

It is the purpose of this chapter to promote the public health, safety and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed to:

A. Protect human life and health;

B. Minimize expenditure of public money and costly flood control projects;

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

D. Minimize prolonged business interruptions;

E. Minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets and bridges located in areas of special flood hazard;

F. Help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize future flood-blight areas;

G. Ensure that potential buyers are notified that property is in an area of special flood hazard;

H. Ensure that those who occupy the areas of special flood hazard assume responsibility for their actions; and

I. Participate in and maintain eligibility for flood insurance and disaster relief. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.030 Methods of reducing flood losses.

In order to accomplish its purposes, this chapter includes methods and provisions for:

A. Restricting or prohibiting uses which are dangerous to health, safety and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities;

B. Requiring that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction;

C. Controlling the alteration of natural floodplains, stream channels and natural protective barriers, which help accommodate or channel floodwaters;

D. Controlling filling, grading, dredging, and other development which may increase flood damage; and

E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards in other areas. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.035 Zero-rise policy.

A. A “zero-rise policy” means any project in a floodplain must be reviewed to determine to not increase flood heights.

B. Any fill material under 500 cubic yards cumulatively placed within a floodplain shall require compensatory excavation necessary to achieve zero net rise.

C. Any fill greater than 500 cubic yards as measured cumulatively within the 100-year floodplain shall require compensatory excavation necessary to achieve zero net rise and an engineering report prepared by a licensed professional engineer identifying the impact of the project and fill on the base flood elevation and upstream or downstream flood hazards. The engineer shall evaluate the impact using the latest HEC-RAS hydraulic modeling or other available modeling consistent with current hydraulic modeling.

D. The compensatory site must remain as a compensatory site in perpetuity. However, if the fill site is behind the airport levee, the compensatory site must function as such until the levee is raised to an elevation above 182 feet NGVD29, or when the site is designed as Zone X. It shall be the applicant’s responsibility to obtain a compensatory fill site and secure such site prior to commencing fill.

E. The compensatory fill site shall be recorded as such with the Lewis County auditor.

F. If the engineering report shows a rise in the base flood elevation or an increase in upstream or downstream impacts, the applicant may be required to modify their project to avoid the impacts and/or apply for and be approved for a Conditional Letter of Map Revision (CLOMR) prior to approval of the development permit.

G. In lieu of compensatory excavation, the applicant may contribute funds for flood storage mitigation and aquatic species enhancement projects within the Chehalis River floodplain. Said fee will be calculated per cubic yard of material, utilizing prevailing wage rates and other associated costs. Said fee will be periodically updated to meet future prevailing wage rates or other costs that may fluctuate. Said fees shall be deposited into the city’s compensatory excavation mitigation fund, which will be utilized solely for capital projects that provide flood storage and habitat enhancement that are on the Chehalis River and its associated floodplain within or adjacent to the city of Chehalis limits. Said fee shall be added to the city’s fee schedule. [Ord. 1122B § 13, 2025; Ord. 982B § 1, 2017; Ord. 958B § 2, 2016.]

17.22.040 Flood hazard area established.

The areas of special flood hazard identified by the Federal Insurance and Mitigation Administration in a scientific and engineering report entitled “The Flood Insurance Study for Chehalis,” dated July 17, 2006, and any revisions thereto, with associated flood insurance rate maps (FIRMs), and any revisions thereto, is hereby adopted by reference and declared to be a part of this chapter. The FIRMs are on file at the Community Development Department, 1321 S. Market Boulevard. The city of Chehalis shall also be empowered to create special flood hazard areas based on best available information, such as the flood of record. Best available information shall be used to determine the flood hazard areas based on elevation data, topographic information and flood-of-record data. [Ord. 1122B § 13, 2025; Ord. 858B § 10, 2010; Ord. 849B § 3, 2009.]

17.22.050 Compliance.

This chapter shall apply to all areas subject to a base flood and/or designated as an area of special flood hazard within the jurisdiction of the city. All development shall hereafter proceed in compliance with the terms of this chapter and other applicable regulations. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.055 Penalties for noncompliance.

No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms of this chapter and other applicable regulations. Violations of the provisions of this chapter by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions), shall be subject to the enforcement and penalties within CMC 17.09.215. [Ord. 1122B § 13, 2025.]

17.22.060 Abrogation and greater restrictions.

This chapter is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions which may be enforced by private action among the affected parties. Where this chapter and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.070 Interpretation.

In the interpretation and application of this chapter, all provisions shall be:

A. Considered as minimum requirements;

B. Liberally construed in favor of the governing body; and

C. Deemed neither to limit nor repeal any other powers granted under state statutes. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.080 Criteria for land management and use.

The standards and definitions contained in this title shall be the minimum standards administered and enforced for flood damage reduction within the city and its urban growth area. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.090 Warning and disclaimer of liability.

The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on unpredictable occasions. Flood heights may be increased by manmade or natural causes. This chapter does not warrant or imply that land outside the areas of special flood hazards or uses permitted within such areas will be free from flooding or flood damages. The city and/or any of its officers or employees shall not be responsible for the accuracy of materials submitted for review and do not guarantee that flood damage will not result from reliance on this chapter or any administrative decision lawfully made thereunder. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.100 Development permit required.

A. A development permit shall be obtained before any construction or development begins within any special flood hazard area established in CMC 17.22.040. The permit shall be for all structures, including manufactured homes, as set forth in the definitions in Chapter 17.21 CMC and for all development, including fill and other activities, also as set forth in the definitions in Chapter 17.21 CMC.

B. Application for development shall be submitted on forms furnished by the city and may include but not be limited to plans in duplicate drawn to scale showing the nature, locations, dimensions, and elevations of the area in question; existing and proposed structures, fill, storage of materials, drainage facilities, and the location of the foregoing. Specifically, the following information is required:

1. Where a structure is to be constructed or substantially improved, the elevation in relation to mean sea level, of the lowest floor (including basement), provided on a current FEMA elevation certificate; and

2. Where a structure is to be floodproofed, certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet floodproofing criteria in CMC 17.22.190, provided on a current FEMA floodproofing certificate; and

3. Where development is proposed in a floodway, an engineering analysis indicating no rise of the base flood elevation; and

4. Any other such information that may be reasonably required by the floodplain administrator in order to review the application; and

5. Description of the extent to which a watercourse will be altered or relocated as a result of proposed development. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.105 Designation, duties, and responsibilities of the floodplain administrator.

A. The director of community development is appointed to administer, implement, and enforce this chapter by granting or denying development permits in accordance with its provisions.

B. The floodplain administrator shall review all development permits to determine that:

1. The permit requirements of this chapter have been satisfied;

2. All necessary permits have been obtained from federal, state, and/or local governmental agencies from which prior approval is required;

3. The site is reasonably safe from flooding;

4. The proposed development is not located in the floodway. If located in the floodway, ensure the encroachment provisions of CMC 17.22.220 are met;

5. Notify FEMA when annexations occur in the special flood hazard area.

C. Interpretation of FIRM Boundaries. The floodplain administrator shall make interpretations where needed, as to exact location of the boundaries of the areas of special flood hazards (e.g., where there appears to be a conflict between a mapped boundary and actual field conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation. Such appeals shall be granted consistent with the standards of CMC 17.09.160.

D. Alteration of Watercourses. Whenever a watercourse is to be altered or relocated, the floodplain administrator shall:

1. Notify adjacent communities and the Department of Ecology prior to any alteration or relocation of a watercourse and submit evidence of such notification to the Federal Insurance Administrator.

2. Ensure that the flood-carrying capacity of the altered or relocated portion of said watercourse is maintained. [Ord. 1122B § 13, 2025.]

17.22.110 Use of other base flood data.

When base flood elevation data has not been provided on official maps, the administrator shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a federal, state, local, or other source, including topographic data, in order to administer this chapter, including application of such information to subdivisions and other proposed development. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.120 Information to be obtained and maintained.

The floodplain administrator shall obtain and maintain the following:

A. Where base flood elevation is provided through the FIS, FIRM, or as required in CMC 17.22.110, the developer shall provide to the floodplain administrator the actual elevation of the lowest floor (including basement), in relation to mean sea level certified by a licensed land surveyor on a current FEMA elevation certificate, of all new or substantially improved structures, and whether or not the structure contains a basement. The floodplain administrator shall maintain this elevation certificate in a permanent file.

B. For all new or substantially improved floodproofed nonresidential structures where base flood elevation data is provided through the FIS, FIRM, or as required by CMC 17.22.110:

1. The developer shall provide to the floodplain administrator the actual elevation of the lowest floor (including basement), in relation to mean sea level and certified by a licensed land surveyor, using a current FEMA elevation certificate; and

2. The developer shall provide to the floodplain administrator the actual elevation of floodproofing, in relation to mean sea level and certified by a licensed land surveyor, and the floodproofing construction certification, certified by a licensed professional engineer or architect, on a current FEMA floodproofing certificate.

3. The floodplain administrator shall maintain such floodproofing certifications.

C. All records pertaining to the provisions of this chapter.

D. Floodway encroachment certifications required by CMC 17.22.220.

E. Record of all variance actions, including justification for their issuance.

F. Improvement and damage calculations. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.130 Variance requirements and criteria.

A. Variances from the standards in this chapter are a Type 3 permit and the decision is issued by the hearing examiner, except for the administrative variances described in subsection (H) of this section.

B. Applications for a variance shall be made on forms furnished by the floodplain administrator.

C. Variances as interpreted in the National Flood Insurance Program are based on the general zoning law principle that they pertain to a physical piece of property; they are not personal in nature and do not pertain to the structure, its inhabitants, economic or financial circumstances. They primarily address small lots in densely populated residential neighborhoods. As such, variances from the flood elevations should be quite rare.

D. Variances shall only be issued upon:

1. A showing of good and sufficient cause;

2. A determination that failure to grant the variance would result in exceptional hardship to the applicant;

3. A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public as identified in CMC 17.22.020, or conflict with existing local laws or ordinances;

4. A determination that the variance is the minimum necessary, considering the flood hazard, to afford relief;

5. For the repair, rehabilitation, or restoration of historic structures, upon a determination that the proposed repair or rehabilitation will not preclude the structure’s continued designation as a historic structure and the variance is the minimum necessary to preserve the historic character and design of the structure; and

6. Upon a showing that the use cannot perform its intended purpose unless it is located or carried out in close proximity to water. This includes only facilities defined in Chapter 17.21 CMC in the definition of “functionally dependent use.”

E. Variances shall not be issued within a designated floodway for a residential structure or if any increase in flood levels during the base flood discharge would result.

F. Generally, the only condition under which a variance from the elevation standard may be issued is for new construction and substantial improvements to be erected on a lot of one-half acre or less in size contiguous to and surrounded by lots with existing structures constructed below the base flood level, providing the provisions within subsection (H) of this section have been fully considered; and provided, that technical justification can demonstrate that the structure cannot be elevated on piers or foundation walls. As the lot size increases, the technical justification required for issuing the variance increases.

G. In reviewing applications for a variance, the hearing examiner shall consider all technical evaluations, relevant factors, and standards specified in other sections of this chapter, and:

1. The danger to life and property due to flooding or erosion damage;

2. The danger that materials may be swept onto other lands to the injury of others;

3. The safety of access to the property in times of flood for ordinary and emergency vehicles;

4. The expected heights, velocity, duration, rate of rise, and sediment transport of the flood waters expected at the site;

5. The susceptibility of the proposed facility and its contents to flood or erosion damage and the effect of such damage on the individual owner;

6. The availability of alternative locations for the proposed use which are not subject to flooding or erosion damage;

7. The relationship of the proposed use to the comprehensive plan, growth management regulations, critical area regulations, the shoreline management program, and floodplain management program for that area;

8. The costs of providing governmental services during and after flood conditions, including maintenance and repair of public utilities and facilities such as sewer, gas, electrical, and water systems, and streets and bridges;

9. The potential of the proposed development project to adversely affect federal, state or locally protected species or habitats;

10. The importance of the services provided by the proposed facility to the community;

11. The necessity of the facility to have a waterfront location, where applicable; and

12. The compatibility of the proposed use with existing and anticipated development.

H. Variances may be issued by the floodplain administrator as a Type 2 permit for:

1. The reconstruction, rehabilitation, or restoration of a historic structure, as defined in Chapter 17.21 CMC.

a. The variance may be granted upon a determination that the proposed repair or rehabilitation will not preclude the structure’s continued designation as a historic structure.

b. The floodplain administrator may place conditions on the variance to make the building more flood resistant and minimize damage, if such measures do not affect the historic character of the building. Such measures may include, but not be limited to, use of flood-resistant materials where possible, protecting mechanical and utility equipment, wet floodproofing, or incorporating temporary measures when flooding is imminent.

2. The floodplain administrator may grant variances to allow at-grade detached accessory structures, as defined in Chapter 17.21 CMC, that exceed the size limit requirement in CMC 17.22.195 when the applicant can demonstrate an exceptional hardship if the variance were not to be granted.

I. The hearing examiner or floodplain administrator shall condition the variance as needed to ensure that the requirements and criteria of this chapter are met.

J. Any applicant to whom a variance is granted shall be given written notice over the signature of a community official that the issuance of a variance to construct a structure with a lowest floor elevation below the flood protection elevation will result in increased premium rates for flood insurance and that construction below the flood protection elevation increases risks to life and property.

K. The floodplain administrator shall maintain a record of all variance actions, including justification for their issuance. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.140 Anchoring.

A. All new construction and substantial improvements, including those related to manufactured homes, shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy.

B. All manufactured homes shall be anchored to prevent flotation, collapse, or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.150 Construction materials and methods.

A. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

B. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

C. Electrical, heating, ventilation, ductwork, plumbing, and air-conditioning equipment and other similar service facilities shall be elevated to the required flood protection elevation or otherwise located so as to prevent water from entering or accumulating within the components during conditions of flooding. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.155 Storage of materials and equipment.

Storage of materials or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning. [Ord. 1122B § 13, 2025.]

17.22.160 Utilities.

A. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems.

B. New and replacement sanitary sewer systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters.

C. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

D. Water wells shall be located on high ground that is not in the floodway. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.165 Subdivision and development proposals.

All development proposals, including subdivisions, shall:

A. Be consistent with the need to minimize flood damage.

B. Have public utilities and facilities, such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage.

C. Have adequate drainage provided to reduce exposure to flood damage.

D. Where subdivision proposals and other proposed developments contain greater than 50 lots or five acres (whichever is the lesser), base flood elevation data shall be included as part of the application.

E. All subdivisions shall provide a building site on each lot, including access, that is suitable for development and is not within the special flood hazard area. [Ord. 1122B § 13, 2025.]

17.22.170 Flood protection elevation.

A. Development within special flood hazard areas which requires elevation or floodproofing shall be elevated or floodproofed to or above the flood protection elevation.

B. The flood protection elevation for residential structures is the base flood elevation plus two feet, or to two feet above the flood of record elevation at the specific location as identified by the city, whichever elevation is higher. In AO zones, the flood protection elevation is two feet above the depth number identified on the FIRM.

C. The flood protection elevation for nonresidential structures is the base flood elevation plus one foot, or to one foot above the flood of record elevation at the specific location as identified by the city, whichever elevation is higher. In AO zones, the flood protection elevation is one foot above the depth number identified on the FIRM.

D. The flood protection elevation for critical facilities is the base flood elevation plus three feet, or to three feet above the flood of record, whichever is higher.

E. New construction and substantial improvement of any residential structure in an unnumbered A zone for which a base flood elevation is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

F. Where elevation data is not available either through the flood insurance study, FIRM, or from another authoritative source, applications for floodplain development shall be reviewed to ensure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.180 Residential construction.

A. In AE and A1-30 zones or other A-zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to the flood protection elevation as described in CMC 17.22.170. Mechanical equipment and utilities shall be waterproofed or elevated to at least the flood protection elevation.

B. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited or shall be designed to automatically equalize hydrostatic forces on exterior walls by allowing for the entry and exit of floodwaters. If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:

1. A minimum of two 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;

2. The bottom of all openings shall be no higher than one foot above the lowest grade;

3. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters, and do not become obstructed during a flood event;

4. A garage attached to a residential structure, constructed with the garage floor slab below the flood protection elevation, must be designed to allow for the automatic entry and exit of floodwaters; and

5. Engineered openings that provide a coverage area shall have an evaluation report from the International Code Council or be designed and certified by a licensed engineer or architect.

C. New construction and substantial improvement of a residential structure in an AO zone shall meet the requirements of CMC 17.22.250.

D. Construction of below-grade crawlspaces is discouraged but may be allowed if:

1. The interior grade of the crawlspace below the base flood elevation is no more than two feet below the lowest adjacent exterior grade;

2. The height of the below-grade crawlspace, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall, does not exceed four feet at any point;

3. The crawlspace contains an adequate drainage system that removes floodwaters from the interior of the crawlspace, such as natural drainage through porous, well-drained soils, and/or constructed drainage systems such as perforated pipes, drainage tiles or gravel or crushed stone drainage by gravity or mechanical means;

4. Any building utility systems within the crawlspace are elevated to the flood protection elevation or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. In particular, all ductwork is elevated above the flood protection elevation or sealed from floodwaters;

5. The velocity of floodwaters at the site does not exceed five feet per second for any crawlspace; and

6. All other minimum criteria set forth in this section are satisfied. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.190 Nonresidential construction.

A. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have:

1. The lowest floor, including basement, along with mechanical equipment and utilities, elevated to the flood protection elevation. The space below the lowest floor shall meet the same standards as described in CMC 17.22.180(B) and (D); or

2. Be floodproofed so that below the flood protection elevation the structure is watertight with walls substantially impermeable to the passage of water; and:

a. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;

b. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this section based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the floodplain administrator;

c. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building constructed to the base flood level will be rated as one foot below that level). [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.195 Detached accessory structures.

This provision applies to accessory structures built at-grade that represent a minimal investment and are used for parking or limited storage only, such as detached garages or small storage sheds. The floodplain administrator may allow certain accessory structures located in the special flood hazard area to be wet floodproofed in lieu of the elevation or dry floodproofing requirement, without a variance, under the following conditions:

A. Use of the accessory structure must be limited to parking of vehicles or limited storage;

B. The portions of the accessory structure located below the base flood elevation must be built using flood-resistant materials;

C. The accessory structure must be adequately anchored to prevent flotation, collapse, and lateral movement;

D. Any machinery or equipment servicing the accessory structure must be elevated or floodproofed to or above the base flood elevation;

E. The accessory structure must comply with floodway encroachment provisions in CMC 17.22.220;

F. The accessory structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with CMC 17.22.180(B), unless the floor is above the base flood elevation;

G. The structure shall have low damage potential and represent a minimal investment;

H. The structure shall not be used for human habitation or occupancy;

I. The structure shall not exceed 600 square feet;

J. Upon completion of the structure, certification in a form acceptable by the floodplain administrator shall be provided that demonstrates the requirements of this section have been satisfied;

K. Accessory structures built at-grade that cannot meet these standards or qualify for a variance shall be constructed following the requirements of CMC 17.22.190; and

L. If the structure is converted to another use, it must be brought into full compliance with the standards governing such use. [Ord. 1122B § 13, 2025.]

17.22.200 Manufactured homes.

All manufactured homes to be placed or substantially improved within zones A1-30, AH, and AE shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at the flood protection elevation as described in CMC 17.22.170 and be securely anchored to an adequately anchored foundation system, as described in CMC 17.22.140, to resist flotation, collapse and lateral movement. Manufactured homes with solid perimeter walls must comply with the flood opening provisions of CMC 17.22.180(B). [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.205 Recreational vehicles.

Recreational vehicles placed on sites within the special flood hazard area are required to either:

A. Be on the site for fewer than 180 days; and

B. Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

C. Meet the requirements of CMC 17.22.200. [Ord. 1122B § 13, 2025.]

17.22.210 Critical facilities.

A. Critical facilities should be afforded additional flood protection due to their nature.

B. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area as identified on the city’s FIRM or the limits of the flood of record, whichever is greater. Construction of new critical facilities shall be permissible within special flood hazard area if no feasible alternative site is available. Critical facilities constructed within the special flood hazard area or the limits of the flood of record shall have the lowest floor elevated to the flood protection elevation. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters.

C. Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.220 Floodways.

Located within areas of special flood hazard are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:

A. Encroachments, including fill, new construction, substantial improvements, and other development are prohibited unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachments would not result in any increase in flood levels during the occurrence of the base flood discharge.

B. Construction or reconstruction of residential structures is prohibited within designated floodways, except for:

1. Repairs, reconstruction, or improvements to a structure which:

a. Do not increase the ground-floor area; and

b. The cost of which does not exceed 50 percent of the market value of the structure, either (i) before the repair, reconstruction, or improvement is started, or (ii) if the structure has been damaged, and is being restored, before the damage occurred; and

c. Any project for improvement of a residential 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 ensure safe living conditions, or to structures identified as historic places, may be excluded in the 50 percent.

2. Repairs, reconstruction, or improvement to an existing farmhouse pursuant to WAC 173-158-075 or substantially damaged residences pursuant to WAC 173-158-076. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.225 Alteration of watercourses.

Repealed by Ord. 1122B. [Ord. 849B § 3, 2009.]

17.22.230 Special flood hazard areas with designated floodways.

Repealed by Ord. 1122B. [Ord. 849B § 3, 2009.]

17.22.240 Special flood hazard areas without designated floodways.

In AE and A1-30 zones with a base flood elevation, but where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including infill) shall be permitted unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of base flood more than one foot at any point within the community. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]

17.22.250 Standards for shallow flood areas (AO zones).

Shallow flooding areas appear on the FIRM as AO zones with depth designations. The base flood depths in these zones range from one to three feet where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In addition to other provisions in this code, the following provisions apply:

A. New construction and substantial improvements of residential structures and manufactured homes within AO zones shall have the lowest floor (including basement) and mechanical equipment elevated above the highest adjacent grade to the structure, to two feet above the depth number specified in the FIRM (at least two feet if no depth number is specified);

B. New construction and substantial improvements of nonresidential structures within the AO zones shall either:

1. Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, to one foot above the depth number specified in the FIRM (at least two feet if no depth number is specified); or

2. Together with attendant utility and sanitary facilities, be completely floodproofed to or above the flood protection elevation so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect;

C. Require adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures. [Ord. 1122B § 13, 2025; Ord. 849B § 3, 2009.]