In all areas of special flood hazards, the following standards are required:

A. Anchoring.

1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.

2. All manufactured homes must likewise 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 (Reference FEMA’s “Manufactured Home Installation in Flood Hazard Areas” guidebook for additional techniques).

B. Construction Materials and Methods.

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

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

3. Electrical, heating, ventilation, plumbing and air-conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.

C. Utilities.

1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system. Water wells shall be located on high ground that is not in the floodway;

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

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

D. Subdivision Proposals.

1. All subdivision proposals shall be consistent with the need to minimize flood damage;

2. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage;

3. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and

4. Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres (whichever is less).

E. Review of Building Permits. Where elevation data is not available either through the flood insurance study or from another authoritative source, applications for building permits shall be reviewed to assure 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. Failure to elevate at least two feet above grade in these zones may result in higher insurance rates.

F. Specific Standards. In all areas of special flood hazards where base flood elevation data has been provided as set forth in BIMC 15.16.030.B or 15.16.040.D.2, the following provisions are required:

1. 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 one foot or more above the BFE. Mechanical equipment and utilities shall be designed so that floodwaters cannot infiltrate or accumulate within any component of the system or elevated least one foot above the BFE.

b. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. 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:

i. 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.

ii. The bottom of all openings shall be no higher than one foot above grade.

iii. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

iv. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

c. New construction and substantial improvement of any residential structure in an unnumbered A zone for which a BFE 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.

d. New construction and substantial improvement of any residential structure in a V, V1 – 30, or VE zone shall meet the requirements in subsection M of this section.

2. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection F.2.a or F.2.b of this section.

a. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

i. 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 commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE, or elevated as required by ASCE 24, whichever is greater. Mechanical equipment and utilities shall be waterproofed or elevated least one foot above the BFE, or as required by ASCE 24, whichever is greater.

ii. If located in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

iii. If located in a V, V1 – 30, or VE zone, the structure shall meet the requirements in this section.

iv. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. 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:

(A) Have a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding.

(B) The bottom of all openings shall be no higher than one foot above grade.

(C) Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwater.

(D) A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

(E) Alternatively, a registered engineer or architect may design and certify engineered openings.

b. If the requirements of subsection F.2.a of this section are not met, then new construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

i. Be dry floodproofed so that below one foot or more above the base flood level the structure is watertight with walls substantially impermeable to the passage of water or dry floodproofed to the elevation required by ASCE 24, whichever is greater;

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

iii. 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 subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in BIMC 15.16.040;

iv. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in this section;

Applicants who are 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 floodproofed to the base flood level will be rated as one foot below). Floodproofing the building an additional foot will reduce insurance premiums.

3. Critical Facility. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the base floodplain. Construction of new critical facilities shall be permissible within the base floodplain if no feasible alternative site is available. Critical facilities constructed within the base floodplain shall have the lowest floor elevated to three feet or more above the level of the base flood elevation at the site, or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility should also be protected to the height utilized above. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the base floodplain shall be provided to all critical facilities to the extent possible.

4. Manufactured Homes. All manufactured homes to be placed or substantially improved within the floodplain shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is one foot or more above the base flood elevation; and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection A.2 of this section.

5. Recreational Vehicles. All recreational vehicles placed on sites are required to either:

a. Be on the site for fewer than 180 consecutive days; or

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 subsection F.4 of this section and the elevation and anchoring requirements for manufactured homes.

6. Enclosed Area Below the Lowest Floor. 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.

G. AE and A1 – 30 Zones With Base Flood Elevations but No Floodways. In areas with BFEs (when a regulatory floodway has not been designated), no new construction, substantial improvements, or other development (including fill) shall be permitted within zones A1 – 30 and AE on the community’s FIRM, 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 the base flood more than one foot at any point within the community.

H. Floodways. Located within areas of special flood hazard established in BIMC 15.16.030.B 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:

1. Prohibit encroachments, including fill, new construction, substantial improvements and other development unless certification by a registered professional engineer is provided demonstrating 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.

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

a. Repairs, reconstruction or improvements to a structure which do not increase the ground floor area; and

b. Repairs, reconstruction or improvements to a structure, the cost of which does not exceed 50 percent of the market value of the structure as determined:

i. Before the repair or reconstruction is started; or

ii. Before damage occurred if the structure is being restored;

c. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions, or structures identified as historic places, may be excluded in the 50 percent limitation of subsection G.2.b of this section.

3. If subsection G.1 of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.

I. Wetlands Management. To the maximum extent possible, avoid the short and long term adverse impacts associated with the destruction or modification of wetlands, especially those activities which limit or disrupt the ability of the wetland to alleviate flooding impacts. The following process should be implemented:

1. Review proposals for development within base floodplains for their possible impacts on wetlands located within the floodplain;

2. Ensure that development activities in or around wetlands do not negatively affect public safety, health, and welfare by disrupting the wetlands’ ability to reduce flood and storm drainage;

3. Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) can be used in conjunction with the community’s FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention.

J. Habitat Impact Assessment. Unless allowed under subsection L of this section, a permit application to develop in the regulatory floodplain shall include an assessment of the impact of the project on federal, state or locally protected species and habitat, water quality and aquatic and riparian habitat. The assessment shall be performed by a qualified professional as defined by Chapter 16.20 BIMC. The assessment shall be:

1. A biological evaluation or biological assessment developed per 50 CFR 402.12 to initiate federal interagency consultation under Endangered Species Act Section 7(a)(2); or

2. Documentation that the activity fits within Section 4(d) of the Endangered Species Act; or

3. Documentation that the activity fits within a habitat conservation plan approved pursuant to Section 10 of the Endangered Species Act, where any such assessment has been prepared or is otherwise made available; or

4. An assessment prepared in accordance with Floodplain Habitat Assessment and Mitigation Draft Regional Guidance, 2011, FEMA Region 10. The assessment shall determine if the project would adversely affect:

a. Species that are federal, state, or local listed as threatened or endangered,

b. The primary constituent elements for critical habitat, when designated,

c. Essential fish habitat designated by the National Marine Fisheries Service (NMFS),

d. Fish and wildlife habitat conservation areas,

e. Other protected areas and elements necessary for species conservation.

K. Habitat Mitigation Plan.

1. If the assessment conducted under subsection J of this section concludes the project is expected to have an adverse effect on water quality and/or aquatic or riparian habitat or habitat functions, the applicant shall provide a plan to mitigate those impacts, in accordance with Floodplain Habitat Assessment and Mitigation Draft Regional Guidance, 2011, FEMA Region 10.

a. If the USFWS or NMFS issues an incidental take permit under Section 10 of the Endangered Species Act, or biological opinion under this section, the permit can be considered to qualify as a plan to mitigate those impacts.

b. If the project is located outside the protected area, the mitigation plan shall include such avoidance, minimization, restoration, or compensation measures so that indirect adverse effects of development in the floodplain (effects to stormwater, riparian vegetation, bank stability, channel migration, hyporheic zones, wetlands, large woody debris, etc.) are mitigated such that equivalent or better habitat protection is provided.

c. No new stream crossings are allowed outside the protected area unless approval has been obtained as stated in subsection K.1.a of this section.

d. If the project is located in the protected area, the mitigation plan shall stipulate avoidance measures as are needed to ensure that there is no adverse effect during any phase of the project.

2. The plan’s habitat mitigation activities shall be incorporated into the proposed project. The floodplain development permit shall be based on the redesigned project and its mitigation components.

3. As required in BIMC 15.16.040, the building official shall not issue a certification of use or a certificate of occupancy until all work identified in the habitat assessment and mitigation plan has been completed or the applicant has provided the necessary assurance that unfinished portions of the project will be completed.

L. The following activities do not require the habitat impact assessment required under subsection J of this section; provided, that all other requirements are met, including federal, state, and local requirements:

1. Repair or remodel of an existing structure, if the repair or remodel is not a substantial improvement or a repair of substantial damage.

2. Expansion of an existing structure that is not greater than 10 percent beyond its existing footprint; provided, that the repair or remodel is not a substantial improvement or a repair of substantial damage. This measurement is counted cumulatively from September 22, 2011.

3. Activities with the sole purpose of creating, restoring, or enhancing natural functions associated with floodplains, streams, lakes, estuaries, marine areas, habitat, and riparian areas, provided the activities do not include structures, grading, fill, or impervious surfaces.

4. Development of open space and recreational facilities, such as parks and trails, that do not include structures, fill, impervious surfaces or removal of more than five percent of the native vegetation on that portion of the property in the regulatory floodplain.

5. Repair to on-site septic systems provided the ground disturbance is the minimal necessary.

6. Alterations in response to emergencies which threaten the public health, safety and welfare or which pose an imminent risk of damage to private property consistent with the requirements of BIMC 16.12.030.B.5.

7. Routine maintenance of landscaping that does not involve grading, excavation, or filling.

8. Removal of noxious weeds and replacement of nonnative vegetation with native vegetation, provided no earth movement occurs.

9. Removal of hazard trees consistent with the requirements of BIMC 18.15.010, Chapter 16.18 BIMC, and BIMC 16.12.030.

10. Normal maintenance of structures, such as reroofing and replacing siding, provided such work does not qualify as a substantial improvement.

11. Normal maintenance of above-ground utilities and facilities, such as replacing downed power lines and utility poles.

12. Normal street and road maintenance, including filling potholes, repaving, and installing signs and traffic signals, but not including expansion of paved areas.

13. Normal maintenance of a levee or other flood control facility prescribed in the operations and maintenance plan for the levee or flood control facility are allowed in the regulatory floodplain without need for a floodplain development permit. Normal maintenance does not include repair from flood damage, expansion of the prism, expansion of the face or toe or addition for protection on the face or toe with rock armor.

14. Normal maintenance, operation or repair of publicly improved recreation areas as long as any such activity does not include expansion of uses and/or facilities into a previously unimproved portion of the regulatory floodplain and is consistent with the standards of Chapter 16.20 BIMC, Critical Areas, best available science or adaptive management plans as recognized by the city.

15. Site investigative work and studies necessary for preparing land use applications.

M. Coastal High Hazard Areas. Located within areas of special flood hazard established in BIMC 15.16.030.B are coastal high hazard areas, designated as zones V1 – 30, VE and/or V. These areas have special flood hazards associated with high velocity waters from surges, and therefore, in addition to meeting all provisions in this code, the following provisions shall also apply:

1. All new construction and substantial improvements in zones V1 – 30 and VE (and V if base flood elevation data is available) on the community’s FIRM shall be elevated on pilings and columns so that:

a. The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated one foot or more above the base flood level; and

b. The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Wind and water loading values shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).

A registered professional engineer or architect shall develop or review the structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of subsections M.1.a and M.1.b of this section.

2. A registered professional surveyor shall obtain and certify the elevation (in relation to mean sea level) of the bottom of the lowest structural member of the lowest floor (excluding pilings and columns) of all new and substantially improved structures in zones V1 – 30, VE, and V on the community’s FIRM and whether or not such structures contain a basement. The local administrator shall maintain a record of all such information.

3. All new construction within zones V1 – 30, VE, and V on the community’s FIRM shall be located landward of the reach of mean high tide.

4. All new construction and substantial improvements within zones V1 – 30, VE, and V on the community’s FIRM shall have the space below the lowest floor either free of obstruction or constructed with nonsupporting breakaway walls, open wood lattice-work, or insect screening intended to collapse under wind and water loads without causing collapse, displacement, or other structural damage to the elevated portion of the building or supporting foundation system. For the purposes of this section, a breakaway wall shall have a design safe loading resistance of not less than 10 and no more than 20 pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by local or state codes) may be permitted only if a registered professional engineer or architect certifies that the design proposed meets the following conditions:

a. Breakaway wall collapse shall result from water load less than that which would occur during the base flood; and

b. The elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and nonstructural). Maximum wind and water loading values to be used in this determination shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).

If breakaway walls are utilized, such enclosed space shall be useable solely for parking of vehicles, building access, or storage. Such space shall not be used for human habitation.

5. Use of fill for structural support of buildings within zones V1 – 30, VE, and V on the community’s FIRM is prohibited.

6. Person-made alteration of sand dunes within zones V1 – 30, VE, and V on the community’s FIRM which would increase potential flood damage is prohibited.

7. All manufactured homes to be placed or substantially improved within zones V1 – 30, V, and VE on the community’s FIRM on sites:

a. Outside of a manufactured home park or subdivision;

b. In a new manufactured home park or subdivision;

c. In an expansion to an existing manufactured home park or subdivision; or

d. In an existing manufactured home park or subdivision on which a manufactured home has incurred “substantial damage” as the result of a flood;

shall meet the standards of subsections M.1 through M.6 of this section, and manufactured homes placed or substantially improved on other sites in an existing manufactured home park or subdivision within zones V1 – 30, V, and VE on the community’s FIRM shall meet the requirements of subsection F.4 of this section.

8. Recreational vehicles placed on sites within zones V1 – 30, V, and VE on the community’s FIRM shall either:

a. Be on the site for fewer than 180 consecutive days;

b. Be fully licensed and ready for highway use, on its 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 subsections F.5 and M.1 through M.6 of this section. (Ord. 2025-09 § 7, 2025; Ord. 2018-28 § 1, 2018; Ord. 2017-04 § 3, 2017; Ord. 2015-28 §§ 4 – 6, 2015; Ord. 2005-05 §§ 4, 5, 2005; Ord. 90-15 § 5, 1990; Ord. 88-22 § 2, 1988)