Chapter 18.38 FP FLOODPLAIN OVERLAY

E. Minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets, and bridges located in the floodplain;

F. Maintain a stable tax base by providing for the sound use of floodprone areas so as to minimize future flood blight areas;

G. Encourage those who occupy areas subject to flooding and channel migration to assume responsibility for their actions;

H. Qualify the city of Tumwater for participation in the National Flood Insurance Program, thereby giving citizens and businesses the opportunity to purchase flood insurance;

I. Maintain the quality of water in rivers, streams, lakes, estuaries, and marine areas and their floodplains so as to protect public water supplies, areas of the public trust, and wildlife habitat protected by the Endangered Species Act;

J. Retain the natural channel, shoreline, and floodplain creation processes and other natural floodplain functions that protect, create, and maintain habitat for threatened and endangered species;

K. Prevent or minimize loss of hydraulic, geomorphic, and ecological functions of floodplains and stream channels.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.015 Relationship to shoreline master program.

If there are any conflicts between the shoreline master program and the floodplain overlay regulations that apply in shoreline jurisdiction, the requirements of shoreline master program apply.

(Ord. O2020-003, Added, 09/15/2020)

18.38.020 Lands to which this chapter applies.

This chapter shall apply to the special flood hazard area within the jurisdiction of the city of Tumwater, as defined in TMC 18.38.080 through 18.38.120.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.030 Approach.

In order to achieve the listed purposes, this chapter:

A. Defines and clarifies the terms and phrases used in this chapter in TMC 18.38.070.

B. Identifies in TMC 18.38.080 through 18.38.120 the special flood hazard area, the protected area and the supporting technical data needed to delineate those areas.

C. Establishes a permit requirement in TMC 18.38.130 through 18.38.200 so that all proposed development that may affect flood hazards, water quality, and habitat is reviewed prior to construction.

D. Sets minimum protection standards in TMC 18.38.210 through 18.38.240 for all development to ensure that the development will not increase the potential for flood damage or adversely affect natural floodplain functions.

E. Sets minimum standards to protect new and substantially improved structures from flood damage in TMC 18.38.250 through 18.38.310.

F. Specifies additional habitat protection criteria in TMC 18.38.320 through 18.38.400. Some small projects do not need a permit. For all other development projects, the applicant must assess their impact on those factors that contribute to increased flood hazard and degradation of habitat. If the assessment concludes that the project will cause an adverse effect outside the protected area, the permit will be denied unless the project impacts are mitigated (avoided, minimized, restored or compensated for).

G. Is based on the “Floodplain Management and the Endangered Species Act – A Model Ordinance” dated November 2013, and its Appendices A through D produced by Region X of the Federal Emergency Management Agency.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.040 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 city of Tumwater; and

C. Deemed neither to limit nor repeal any other powers granted under state statutes.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.050 Abrogation and greater restrictions.

Where this chapter and another code, ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.060 Warning and disclaimer of liability.

The degree of property and habitat protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods and movement of channels outside of mapped channel migration areas can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This chapter does not imply that land outside the regulated areas, or development permitted within such areas, will be free from flood or erosion damage. This chapter shall not create liability on the part of the city of Tumwater or any officer or employee thereof for any damage to property or habitat that result from reliance on this chapter or any administrative decision lawfully made hereunder.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.070 Definitions.

Unless specifically defined below, terms or phrases used in this chapter shall be interpreted so as to give them the meaning they have in common usage and to give this chapter its most reasonable application.

“Adversely affect/adverse effect” means effects that are a direct or indirect result of the proposed action, or its interrelated or interdependent actions, and the effect is not discountable, insignificant or beneficial. Discountable effects are extremely unlikely to occur. Insignificant effects relate to the size of the impact and should never reach the scale where a take occurs. Based on best judgment, a person would not: (A) be able to meaningfully measure, detect, or evaluate insignificant effects; or (B) expect discountable effects to occur. Beneficial effects are contemporaneous positive effects without any adverse effects. In the event that the overall effect of the proposed action is beneficial, but is also likely to cause some adverse effects, then the proposed action is considered to result in an adverse effect.

“Alteration of watercourse” means any action that will change the location of the channel occupied by water within the banks of any portion of a riverine water body.

“Appurtenant structure” means a structure which is on the same parcel of property as the principal structure to be insured and the use of which is incidental to the use of the principal structure.

“Area of special flood hazard” means the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. It is shown on the flood insurance rate map (FIRM) as zone A, AO, AH, A1-30, AE, A99, AR (V, VO, V1-30, VE). “Special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard.”

“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year (also referred to as the “one-hundred-year flood”). The area subject to the base flood is the special flood hazard area (SFHA) designated on flood insurance rate maps (FIRMs) as zones “A” or “V” including AE, AO, AH, A1-99 and VE.

“Base flood elevation (BFE)” means the elevation of the base flood above the datum of the effective FIRM.

“Basement” means any area of the structure having its floor sub-grade (below ground level) on all sides.

“Channel migration zone” means the area within the lateral extent of likely stream channel movement due to stream bank destabilization and erosion, rapid stream incision, aggradation, avulsions, and shifts in location of stream channels.

“Critical facility” means a facility necessary to protect the public health, safety and welfare during a flood. Critical facilities include, but are not limited to, schools, nursing homes, hospitals, police, fire and emergency operations installations, water and wastewater treatment plants, electric power stations, and installations which produce, use, or store hazardous materials or hazardous waste (other than consumer products containing hazardous substances or hazardous waste intended for household use).

“Development” means any manmade change to improved or unimproved real estate in the special flood hazard area (SFHA), including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations, subdivision of land, removal of more than five percent of the native vegetation on the property, alteration of natural site characteristics, or storage of equipment or materials.

“Dry floodproofing” means any combination of structural and nonstructural measures that prevent floodwaters from entering a structure.

“Elevation certificate” means the official form used to provide elevation information necessary to ensure compliance with provisions of this chapter and determine the proper flood insurance premium rate.

“FEMA” means the Federal Emergency Management Agency, the agency responsible for administering the National Flood Insurance Program (NFIP).

“Fish and wildlife habitat conservation area” means lands needed to maintain species in suitable habitats within their natural geographic distribution so that isolated subpopulations are not created. These areas are designated by the city of Tumwater pursuant to the Washington State Growth Management Act and implementing regulations.

“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from:

A. The overflow of inland or tidal waters; and/or

B. The unusual and rapid accumulation of runoff of surface waters from any source.

C. The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in subsection (A) of this definition.

“Flood elevation study (FES)” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as a flood insurance study (FIS).

“Flood insurance rate map (FIRM)” means the official map on which the Federal Emergency Management Agency (FEMA) has delineated both the special flood hazard areas and the risk premium zones applicable to the city of Tumwater.

“Flood insurance study (FIS)” means the official report provided by the Federal Emergency Management Agency that includes flood profiles, the flood insurance rate map (FIRM), and the water surface elevation of the base flood.

“Flood protection elevation (FPE)” means the elevation above the datum of the effective FIRM to which new and substantially improved structures must be protected from flood damage.

“Floodplain administrator” means the community official designated by title to administer and enforce the floodplain management regulations.

“Floodproofing” means any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents. Floodproofed structures are those that have the structural integrity and design to be impervious to floodwater below the base flood elevation (BFE).

“Floodway” means the channel of a stream or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot at any point. Also referred to as “regulatory floodway.”

“Functionally dependent use” means a use that must be located or carried out close to water, e.g., docking or port facilities necessary for the unloading of cargo or passengers or shipbuilding and ship repair, and does not include long term storage or related manufacturing facilities.

“Highest adjacent grade” means the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

“Historic structure” means a structure that:

A. Is listed on the National Register of Historic Places, the Washington Heritage Register, or the Washington Heritage Barn Register; or

B. Has been certified to contribute to the historical significance of a registered historic district.

“Hyporheic zone” means a saturated layer of rock or sediment beneath and/or adjacent to a stream channel that contains some proportion of channel water or that has been altered by channel water infiltration.

“Impervious surface” means a hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of stormwater.

“Lowest floor” means the lowest floor of the lowest enclosed area (including basement or crawlspace). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access, or storage in an area other than a basement area, is not considered a structure’s lowest floor; provided, that such enclosure is compliant with TMC 18.38.260(H) (i.e., provided there are adequate openings to allow floodwaters into the area).

“Manufactured home” means 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 attached to the required utilities. The term “manufactured home” does not include a “recreational vehicle.”

“Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.

“Mean sea level” means, for the purposes of the National Flood Insurance Program (NFIP), the vertical datum to which base flood elevations (BFEs) shown on a community’s flood insurance rate map (FIRM) are referenced.

“Native vegetation” means plant species that are indigenous to the community’s area and that reasonably could be expected to naturally occur on the site.

“Natural floodplain functions” means the contribution that a floodplain makes to support habitat, including, but not limited to, providing flood storage and conveyance, reducing flood velocities, reducing sedimentation, filtering nutrients and impurities from runoff, processing organic wastes, moderating temperature fluctuations, and providing breeding and feeding grounds, shelter, and refugia for aquatic or riparian species.

“New construction” means structures for which the “start of construction” commenced on or after the effective date of this chapter and includes any subsequent improvements to such structures. For floodplain management purposes, “new construction” means structures for which the “start of construction” commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures.

“Protected area” means the lands that lie within the boundaries of the floodway, the riparian habitat zone, and the channel migration area. Because of the impact that development can have on flood heights and velocities and habitat, special rules apply in the protected area.

“Recreational vehicle” means a vehicle:

A. Built on a single chassis; and

B. Four hundred square feet or less when measured at the largest horizontal projection; and

C. Designed to be self-propelled or permanently towable by an automobile or light duty truck; and

D. Designed primarily for use as temporary living quarters for recreational, camping, travel, or seasonal use, not as a permanent dwelling.

“Riparian” means of, adjacent to, or living on the bank of a river, lake, pond, ocean, sound, or other water body.

“Riparian habitat zone” means the water body and adjacent land areas that are likely to support aquatic and riparian habitat as detailed in TMC 18.38.110(C).

“Special flood hazard area (SFHA)” means the land subject to inundation by the base flood. Special flood hazard areas are designated on flood insurance rate maps (FIRMs) with the letters “A” or “V” including AE, AO, AH, A1-99 and VE. The special flood hazard area is also referred to as the area of special flood hazard or SFHA.

“Start of construction” includes substantial improvement, and means the actual start of construction, repair, reconstruction, rehabilitation, addition, placement or other improvement that occurred before the permit’s expiration date. The actual start is either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory structures not occupied as dwelling units or not part of the main structure. For a substantial improvement, the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.

“Structure” means a walled and roofed building, including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.

“Substantial damage” means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed fifty percent of the market value of the structure before the damage occurred. “Substantial damage” also means flood-related damage sustained by a structure on two separate occasions during a ten-year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds twenty-five percent of the market value of the structure before the damage occurred.

“Substantial improvement” means any repair, reconstruction, rehabilitation, addition, replacement, or other improvement of a structure, the cost of which equals or exceeds fifty percent of the market value of the structure before the start of construction of the improvement. This term includes structures which have incurred substantial damage, regardless of the actual repair work performed. The term does not include 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 any alteration of a historic structure; provided, that the alteration will not preclude the structure’s continued designation as a historic structure.

“Variance” means a grant of relief from the requirements of this chapter which permits construction in a manner that would otherwise be prohibited by this chapter.

“Water typing” means a system for classifying water bodies according to their size and fish habitat characteristics. The Washington Department of Natural Resources’ Forest Practices Water Typing classification system is hereby adopted by reference. The system defines four water types:

A. Type “S” = shoreline: streams that are designated “shorelines of the state,” including marine shorelines.

B. Type “F” = fish: streams that are known to be used by fish or meet the physical criteria to be potentially used by fish.

C. Type “Np” = nonfish perennial streams.

D. Type “Ns” = nonfish seasonal streams.

“Zone” means one or more areas delineated on the FIRM. The following zones may be used on the adopted FIRM. The special flood hazard area (SFHA) is comprised of the A and V zones.

“A” means SFHA where no base flood elevation (BFE) is provided.

“A#” means numbered A zones (e.g., A7 or A14), SFHA with an elevation BFE.

“AE” means SFHA with an elevation BFE.

“AO” means SFHA subject to inundation by shallow flooding usually resulting from sheet flow on sloping terrain, with average depths between one and three feet. Average flood depths are shown.

“AH” means SFHA subject to inundation by shallow flooding (usually areas of ponding) with average depths between one and three feet. BFEs are shown.

“B” means the area between the SFHA and the five-hundred-year flood of the primary source of flooding. It may also be an area with a local, shallow flooding problem or an area protected by a levee.

“C” means an area of minimal flood hazard, as above the five-hundred-year flood level of the primary source of flooding. B and C zones may have flooding that does not meet the criteria to be mapped as a special flood hazard area, especially ponding and local drainage problems.

“D” means area of undetermined but possible flood hazard.

“V” means the SFHA subject to coastal high hazard flooding including waves of three feet or greater in height. There are three types of V zones: V, V#, and VE, and they correspond to the A zone designations.

“X” means the area outside the mapped SFHA.

“Shaded X” means the same as a zone B, above.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.080 Area to be regulated.

The area to be regulated is comprised of the special flood hazard area and all protected areas within the special flood hazard area within the jurisdiction of the city of Tumwater. The term also includes areas delineated pursuant to TMC 18.38.120.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.090 Special flood hazard area.

A. The special flood hazard area (SFHA) is the area subject to flooding by the base flood and subject to the provisions of this chapter. It is identified by the Federal Emergency Management Agency in a scientific and engineering report entitled, “Flood Insurance Study for Thurston County, Washington and Incorporated Areas,” dated May 8, 2024, and any revisions thereto, with an accompanying Flood Insurance Rate Map (FIRM) for Thurston County, Washington, and Incorporated Areas, dated May 8, 2024, and any revisions thereto, which are hereby adopted by reference and declared to be a part of this chapter. The flood insurance study (FIS) and the FIRM are on file at Tumwater City Hall, 555 Israel Road SW, Tumwater, Washington 98501.

B. Upon receipt of a floodplain development permit application, the floodplain administrator shall compare the elevation of the site to the base flood elevation (BFE). A development project is not subject to the requirements of this chapter if it is located on land that can be shown to be:

1. Outside the protected area; and

2. Higher than the BFE as demonstrated by an elevation certificate.

The floodplain administrator shall inform the applicant that the project will still be subject to the flood insurance purchase requirements unless the owner receives a letter of map amendment from FEMA.

C. The floodplain administrator shall make interpretations where needed, as to the exact location of the boundaries of the SFHA and the protected area (e.g., where there appears to be a conflict between the mapped SFHA boundary and actual field conditions as determined by the BFE and ground elevations). The applicant may appeal the floodplain administrator’s interpretation of the location of the boundary to the hearing examiner.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2016-009, Amended, 07/09/2016; Ord. O2015-007, Amended, 02/02/2016)

18.38.100 Flood hazard data.

A. The base flood elevation (BFE) for the SFHAs of the city of Tumwater shall be as delineated on the one-hundred-year flood profiles in the Flood Insurance Study for Thurston County, Washington, and Incorporated Areas.

B. The BFE for each SFHA delineated as a “zone AH” or “zone AO” shall be that elevation (or depth) delineated on the flood insurance rate map (FIRM). Where base flood depths are not available in zone AO, the base flood elevation shall be considered to be two feet above the highest grade adjacent to the structure.

C. The BFE for all other SFHAs shall be as defined in subsection F of this section and 18.38.120(C).

D. The flood protection elevation (FPE) shall be the base flood elevation plus one foot.

E. The floodway shall be as delineated on the FIRM or in accordance with subsection F of this section and TMC 18.38.120(D).

F. Where BFE and floodway data have not been provided in special flood hazard areas in accordance with TMC 18.38.090, the floodplain administrator shall obtain, review, and reasonably utilize any BFE and floodway data available from a federal, state, or other source.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.110 Protected area.

A. The protected area is comprised of those lands that lie within the boundaries of the floodway, the riparian habitat zone, and the channel migration area.

B. In riverine areas, where a floodway has not been designated in accordance with TMC 18.38.100(E) and (F) and 18.38.120(D), the protected area is comprised of those lands that lie within the boundaries of the riparian habitat zone, the channel migration area, and the SFHA.

C. Riparian Habitat Zone. The riparian habitat zone includes those watercourses within the SFHA and adjacent land areas that are likely to support aquatic and riparian habitat.

1. The size and location of the riparian habitat zone is dependent on the type of water body. The riparian habitat zone includes the water body and adjacent lands, measured perpendicularly from ordinary high water on both sides of the water body:

a. Type S streams that are designated “shorelines of the state”: two hundred fifty feet.

b. Type F streams (fish bearing) streams greater than five feet wide and marine shorelines: two hundred feet.

c. Type F streams less than five feet wide and lakes: one hundred fifty feet.

d. Type N (nonsalmonid-bearing) perennial and seasonal streams with unstable slopes: two hundred twenty-five feet.

e. All other Type N (nonsalmonid-bearing) perennial and seasonal streams: one hundred fifty feet.

2. The riparian habitat zone shall be delineated on the site plan by the applicant at the time of application for subdivision approval or floodplain development permit for all development proposals within three hundred feet of any stream or shoreline.

D. Channel Migration Area.

1. The channel migration area shall be the channel migration zone as delineated plus fifty feet.

2. Where more than one channel migration zone has been delineated, the floodplain administrator shall use the delineation that has been adopted for other local regulatory purposes.

3. Where a channel migration zone has not yet been mapped, the provisions of TMC 18.38.120(E) shall apply at the time of permit application.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.120 New regulatory data.

A. All requests to revise or change the flood hazard data, including requests for a letter of map revision and a conditional letter of map revision shall be reviewed by the floodplain administrator.

1. The floodplain administrator shall not sign the community acknowledgement form for any requests based on filling or other development, unless the applicant for the letter documents that such filling or development is in compliance with this chapter.

2. The floodplain administrator shall not approve a request to revise or change a floodway delineation until FEMA has issued a conditional letter of map revision that approves the change.

B. If an applicant disagrees with the regulatory data prescribed by this chapter, he/she may submit a detailed technical study needed to replace existing data with better data in accordance with FEMA mapping guidelines or Regional Guidance for Hydrologic and Hydraulic Studies in Support of the Model Ordinance for Floodplain Management under the National Flood Insurance Program and the Endangered Species Act FEMA Region X, 2010. If the data in question are shown on the published FIRM, the submittal must also include a request to FEMA for a conditional letter of map revision.

C. Where base flood elevation data are not available in accordance with TMC 18.38.100, applicants for approval of new subdivisions and other proposed developments shall include such data with their permit applications.

D. Where floodway delineation is not available in accordance with TMC 18.38.100, the floodway will be designated to be one-half the distance of the mapped one-hundred-year floodplain at any point, and the prohibition on floodway development adheres, unless a floodway study indicates otherwise. This provision applies to any floodplain development permit, including those for substantial improvements.

E. Where channel migration zone data are not available in accordance with TMC 18.38.110(D), the permit applicant shall either:

1. Designate the entire SFHA as the channel migration zone; or

2. Identify the channel migration area in accordance with Regional Guidance for Hydrologic and Hydraulic Studies in Support of the Model Ordinance for Floodplain Management under the National Flood Insurance Program and the Endangered Species Act, FEMA Region X, 2012.

F. All new hydrologic and hydraulic flood studies conducted pursuant to this section shall consider future conditions, and the cumulative effects from anticipated future land use changes, in accordance with Regional Guidance for Hydrologic and Hydraulic Studies in Support of the Model Ordinance for Floodplain Management under the National Flood Insurance Program and the Endangered Species Act, FEMA Region X, 2012.

G. The floodplain administrator shall use the most restrictive data available for the channel migration zone, floodways, future conditions, and riparian habitat areas.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.130 Floodplain development permit required.

A floodplain development permit is required before construction or development begins within the special flood hazard area (SFHA) established in TMC 18.38.090. The permit shall be for all development as set forth in TMC 18.38.070, Definitions.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.140 Floodplain development permit application.

Application for a floodplain development permit shall be made on forms furnished by the floodplain administrator and shall include, but are not limited to:

A. One or more site plans, drawn to scale, showing:

1. The nature, location, dimensions, and elevations of the property in question;

2. Names and location of all lakes, water bodies, waterways and drainage facilities within three hundred feet of the site;

3. The elevations of the ten-, fifty-, one-hundred-, and five-hundred-year floods, where such data are available;

4. The boundaries of the SFHA, floodway, riparian habitat zone, and channel migration area, delineated in accordance with TMC 18.38.080 through 18.38.120;

5. The proposed drainage system including, but not limited to, storm sewers, overland flow paths, detention facilities and roads;

6. Existing and proposed structures, fill, pavement and other impervious surfaces, and sites for storage of materials;

7. All wetlands;

8. Designated fish and wildlife habitat conservation areas, and habitat areas identified for conservation or protection under state or federal or local laws or regulations (e.g., Endangered Species Act, Magnuson-Stevens Fishery Conservation and Management Act, Growth Management Act, Shorelines Management Act, Priority Habitat and Species List); and

9. Existing native vegetation and proposed revegetation.

B. If the proposed project involves grading, excavation, or filling, the site plan shall include proposed post-development terrain at one-foot contour intervals.

C. If the proposed project includes a new structure, substantial improvement, or repairs to a substantially damaged structure that will be elevated, the application shall include the flood protection elevation (FPE) for the building site and the proposed elevations of the following:

1. The top of bottom floor (including basement, crawlspace, or enclosure floor).

2. The top of the next higher floor.

3. The bottom of the lowest horizontal structural member (in V zones only).

4. The top of the slab of an attached garage.

5. The lowest elevation of machinery or equipment servicing the structure.

6. The lowest adjacent (finished) grade next to structure.

7. The highest adjacent (finished) grade next to structure.

8. The lowest adjacent grade at the lowest elevation of a deck or stairs, including structural support.

D. If the proposed project includes a new structure, substantial improvement, or repairs to a substantially damaged nonresidential structure that will be dry floodproofed, the application shall include the FPE for the building site, the elevation in relation to the datum of the effective FIRM to which the structure will be dry floodproofed, and a certification by a registered professional engineer or licensed architect that the dry floodproofing methods meet the floodproofing criteria in TMC 18.38.270.

E. If a project will alter the base flood elevation data (BFE) or boundaries of the SFHA, the project applicant shall provide the floodplain administrator with engineering documentation and analysis regarding the proposed change. If the change to the BFE or boundaries of the SFHA would normally require a letter of map change, the project approval shall be conditioned accordingly.

F. The proposed project must be designed and located so that new structural flood protection is not needed.

G. The application shall include a description of the extent to which a stream, lake, or other water body, including its shoreline, will be altered or relocated as a result of the proposed development.

1. Bank stabilization measures along salmonid-bearing streams, channel migration zones, and along estuarine and marine shorelines must be minimized to the maximum extent possible. If bank stabilization measures are necessary, bioengineered armoring of streambanks and shorelines must be used.

2. Channel Migration. No activity is allowed that limits the natural meandering pattern of the channel migration zone; however, natural channel migration patterns may be enhanced or restored.

H. The application shall include documentation that the applicant will apply for all necessary permits required by federal, state, or local law. The application shall include written acknowledgment that the applicant understands that the final certification of use or certificate of occupancy will be issued only if the applicant provides copies of the required federal, state, and local permits or letters stating that a permit is not required. The floodplain permit is not valid if those other permits and approvals are not obtained prior to any ground disturbing work or structural improvements.

I. The application shall include acknowledgment by the applicant that representatives of any federal, state or local unit of government with regulatory authority over the project are authorized to enter upon the property to inspect the development.

J. The application shall include the elevation in relation to mean sea level of the lowest floor (including basement) of all structures recorded on a current elevation certificate with section B completed by the floodplain administrator.

K. The application shall include the elevation in relation to mean sea level to which any structure has been floodproofed.

L. The application shall include, where development is proposed in a floodway, an engineering analysis indicating no rise of the base flood elevation (BFE).

M. The application shall include any other such information that may be reasonably required by the floodplain administrator in order to review the application.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.150 Floodplain development permit expiration.

If there has been no start of construction, a floodplain development permit shall expire one hundred eighty days after the date of issuance. Where the applicant documents a need for an extension beyond this period due to conditions beyond the applicant’s control, the floodplain administrator may authorize one or more extensions.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.160 Designation of the floodplain administrator.

The floodplain administrator is hereby appointed to administer and implement this chapter by granting or denying floodplain development permit applications in accordance with its provisions. The community development director, in accordance with 44 C.F.R. 59.22(b)(1), may designate the “floodplain administrator” to be an agency (department), a full-time staff person, a part-time staff assignment, or a contractor to the community.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.170 Duties of the floodplain administrator.

Duties of the floodplain administrator shall include, but not be limited to:

A. Review all floodplain development permits to determine that the permit requirements of this chapter have been satisfied.

B. Review all floodplain development permits to determine that all necessary permits have been obtained from those federal, state, or local governmental agencies from which prior approval is required, including those local, state or federal permits that may be required to assure compliance with the Endangered Species Act and/or other appropriate state or federal laws.

C. Review all floodplain development permits to determine if the proposed development is located in the floodway. If located in the floodway, ensure that the provisions of TMC 18.38.320 through 18.38.400 are met.

D. Ensure that all development activities within the special flood hazard area (SFHA) of the jurisdiction of the city of Tumwater meet the requirements of this chapter.

E. Inspect all development projects before, during and after construction to ensure compliance with all provisions of this chapter, including proper elevation of the structure.

F. Maintain for public inspection all records pertaining to the provisions of this chapter.

G. Submit reports to include the projects for which they issue floodplain development permits, including effects to flood storage, fish habitat, and all indirect effects of development and mitigation provided to FEMA as required for the National Flood Insurance Program (NFIP).

H. Notify FEMA of any proposed amendments to this chapter.

I. Cooperate with state and federal agencies to improve flood and other technical data and notify FEMA of any new data that would revise the FIRM.

J. Interpretations as to exact location of the boundaries of the areas of special flood hazards where needed (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 44 CFR 60.6 of the Rules and Regulations of the NFIP.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.180 Records.

A. Where base flood elevation data (BFE) have been obtained pursuant to TMC 18.38.100 and 18.38.120, the floodplain administrator shall obtain, record, and maintain the actual “finished construction” elevations (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures, for the locations listed in TMC 18.38.140(C), and whether or not the structure contains a basement. This information shall be recorded on a current FEMA Elevation Certificate, signed and sealed by a professional land surveyor currently licensed in the state of Washington.

B. For all new or substantially improved dry floodproofed nonresidential structures, where BFE data has been obtained pursuant to TMC 18.38.100 and 18.38.120, the floodplain administrator shall:

1. Obtain, record and maintain the elevation (in relation to mean sea level) to which the structure was floodproofed.

2. This information shall be recorded on a current FEMA floodproofing certificate by a professional engineer currently licensed in the state of Washington.

C. Where elevation data is not available, either through the FIS, FIRM, or from another authoritative source (as required by TMC 18.38.100(F)), the floodplain administrator shall review applications for floodplain development to assure that proposed construction will be reasonably safe from flooding based on the use of historical data, high water marks, photographs of past flooding, etc., where available.

Failure to elevate habitable buildings at least two feet above the highest adjacent grade in these zones may result in higher insurance rates.

D. The floodplain administrator shall obtain, record, and maintain the records for public inspection of the following:

1. Certification required by TMC 18.38.360(A)(1).

2. Records of all variance actions, including justification for their issuance.

3. Improvement and damage calculations.

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

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.190 Certificate of occupancy.

A. A certification of use for the property or a certificate of occupancy for a new or substantially improved structure or an addition shall not be issued until:

1. The permit applicant provides a properly completed, signed and sealed elevation or floodproofing certificate showing finished construction data as required by TMC 18.38.180;

2. If a mitigation plan is required by TMC 18.38.380 and 18.38.390, all work identified in the plan has been completed according to the plan’s schedule;

3. The applicant provides copies of all required federal, state, and local permits noted in the permit application per TMC 18.38.140(G);

4. All other provisions of this chapter have been met.

B. The floodplain administrator may accept a performance bond or other security that will ensure that unfinished portions of the project will be completed after the certification of use or certificate of occupancy has been issued.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.200 Variances.

A. In reviewing applications for a variance, the hearings examiner shall consider all technical evaluations, all relevant factors, 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 floodwaters and the effects of wave action, if applicable, 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 channel migration and are not in designated fish and wildlife habitat conservation areas;

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 destroy or adversely affect a fish and wildlife habitat conservation area or create an adverse effect to federal, state or locally protected species or habitat;

10. The potential of the proposed development project to affect, or be affected by, channel migration;

11. Is the minimum necessary to grant relief; and

12. Must be compliant with the ESA.

B. No variance shall be granted to the requirements of this chapter unless the applicant demonstrates that:

1. The development project cannot be located outside the special flood hazard area;

2. An exceptional hardship would result if the variance were not granted;

3. The relief requested is the minimum necessary;

4. The applicant’s circumstances are unique and do not represent a problem faced by other area properties;

5. If the project is within a designated floodway, no increase in flood levels during the base flood discharge would result;

6. The project will not adversely affect features or quality of habitat supporting local, state or federally protected fish or wildlife;

7. There will be no additional threat to public health, safety, beneficial stream or water uses and functions, or creation of a nuisance;

8. There will be no additional public expense for flood protection, lost environmental functions, rescue or relief operations, policing, or repairs to streambeds, shorelines, banks, roads, utilities, or other public facilities; and

9. All requirements of other permitting agencies will still be met.

C. Variances requested in connection with restoration of a historic site, building or structure may be granted using criteria more permissive than the above requirements, provided:

1. The repair or rehabilitation is the minimum necessary to preserve the historic character and design of the site, building or structure; and

2. The repair or rehabilitation will not result in the site, building or structure losing its historic designation.

D. Variances may be requested for new construction, substantial improvements, and other development necessary for the conduct of functionally dependent uses provided:

1. There is good and sufficient cause for providing relief;

2. The variance is the minimum necessary to provide relief;

3. The variance does not cause a rise in the one-hundred-year flood level within the regulatory floodway;

4. The project will not adversely affect federal, state or locally protected fish, wildlife and their habitat or the functions associated with their habitat.

E. Variances to the provisions of TMC 18.38.250 through 18.38.310 may be issued for a structure on a small or irregularly shaped lot contiguous to and surrounded by lots with existing structures constructed below the FPE, providing the other variance criteria are met. The applicant for such a variance shall be notified, in writing, that the structure (1) will be subject to increased premium rates for flood insurance up to amounts as high as $25.00 for $100.00 of insurance coverage and (2) such construction below the FPE increases risks to life and property. Such notification shall be maintained with a record of all variance actions.

F. Variances pertain to a physical piece of property. They are not personal in nature and are not based on the inhabitants or their health, economic, or financial circumstances.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.210 Development and subdivisions.

This section applies to all development and subdivision proposals. Subdivision proposals include short subdivisions, short plats, binding site plans, planned developments, and new and expansions to manufactured housing parks.

A. All proposals shall be consistent with the need to minimize flood damage.

B. A proposed subdivision must have one or more new lots in the special flood hazard area (SFHA) set aside for open space use through deed restriction, easement, subdivision covenant, or donation to a public agency.

1. In the SFHA outside the protected area, zoning must maintain a low density of floodplain development.

2. SFHA outside the protected area in which the current zoning is less than five acres must maintain the current zoning.

3. The density of the development in the portion of the development outside the SFHA may be increased to compensate for the amount of land in the SFHA preserved as open space in accordance with TMC Title 18.

C. If a parcel has a buildable site outside the special flood hazard area, it shall not be subdivided to create a new lot, tract, or parcel within a binding site plan that does not have a buildable site outside the special flood hazard area. This provision does not apply to lots set aside from development and preserved as open space.

D. All proposals shall have utilities and facilities, such as sewer, gas, electrical, and water systems, located and constructed to minimize or eliminate flood damage.

E. All subdivision proposals shall ensure that there is at least one access road connected to land outside the SFHA with the surface of the road at or above the FPE wherever possible.

F. All proposals shall have adequate drainage provided to avoid exposure to water damage.

G. A final recorded subdivision shall include a notice that part of the property is in the SFHA, riparian habitat zone and/or channel migration area, as appropriate.

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

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.220 Site design.

A. Structures and other development shall be located to avoid flood damage.

1. If a lot has a buildable site out of the special flood hazard area, all new structures shall be located in that area, when possible.

2. If a lot does not have a buildable site out of the special flood hazard area, all new structures, pavement, and other development must be sited in the location that has the least impact on habitat by locating the structures as far from the water body as possible or placing the structures on the highest land on the lot.

3. A minimum setback of fifteen feet from the protected area shall be required for all structures.

4. If the proposed project does not meet the criteria of subsections A and B of this section, a habitat impact assessment shall be conducted pursuant to TMC 18.38.380 and, if necessary, a habitat mitigation plan shall be prepared and implemented pursuant to TMC 18.38.390.

B. All new development shall be designed and located to minimize the impact on flood flows, flood storage, water quality, and habitat.

1. Stormwater and drainage features shall incorporate low impact development techniques, if technically feasible, that mimic predevelopment hydrologic conditions, such as stormwater infiltration, rain gardens, grass swales, filter strips, disconnected impervious areas, permeable pavement, and vegetative roof systems.

2. If the proposed project will create new impervious surfaces so that more than ten percent of the portion of the lot in the special flood hazard area is covered by impervious surface, the applicant shall demonstrate that there will be no net increase in the rate and volume of the stormwater surface runoff that leaves the site or that the adverse impact is mitigated, as provided by TMC 18.38.380 and 18.38.390.

C. The site plan required in TMC 18.38.140 shall account for surface drainage to ensure that:

1. Existing and new buildings on the site will be protected from stormwater runoff; and

2. The project will not divert or increase surface water runoff onto neighboring properties.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.230 Hazardous materials.

A. No new development shall create a threat to public health, public safety, or water quality. Chemicals, explosives, gasoline, propane, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other materials that are hazardous, toxic, or a threat to water quality are prohibited from the special flood hazard area. This prohibition does not apply to small quantities of these materials kept for normal household use. This prohibition does not apply to the continued operations of existing facilities and structures, reuse of existing facilities and structures, or functionally dependent facilities or structures.

B. If the proposed project cannot meet subsection A of this section then a habitat assessment must be conducted in accordance with TMC 18.38.380 and 18.38.390.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.240 Critical facilities.

A. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area.

B. Construction of new critical facilities in the special flood hazard area shall be permissible if no feasible alternative site is available, provided:

1. Critical facilities shall have the lowest floor elevated three feet above the base flood elevation or to the height of the five-hundred-year flood, whichever is higher. If there is no available data on the five-hundred-year flood, the permit applicants shall develop the needed data in accordance with FEMA mapping guidelines.

2. Access to and from the critical facility shall be protected to the elevation of the five-hundred-year flood.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.250 Standards for protection of structures.

The provisions of this section shall apply in the special flood hazard area. All new structures and substantial improvements shall be protected from flood damage below the flood protection elevation. This section’s protection requirement applies to all new structures and substantial improvements, which include:

A. Construction or placement of a new structure.

B. Reconstruction, rehabilitation, or other improvement that will result in a substantially improved building.

C. Repairs to an existing building that has been substantially damaged.

D. Placing a manufactured home on a site.

E. Placing a recreational vehicle or travel trailer on a site for more than one hundred eighty days.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.260 Flood protection standards.

A. In AE and A1-30 zones or other A zoned areas where the base flood elevation data (BFE) has been determined or can be reasonably obtained, all new structures and substantial improvements of any structure shall have the lowest floor, including basement, elevated at least one foot above the BFE.

B. The structure shall be aligned parallel with the direction of flood flows where practicable.

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

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

E. 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.

F. All materials below the FPE shall be resistant to flood damage and firmly anchored to prevent flotation. Materials harmful to aquatic wildlife, such as creosote, are prohibited below the FPE.

G. Electrical, heating, ventilation, duct work, plumbing, and air-conditioning equipment and other service facilities shall be elevated above the FPE. Water, sewage, electrical, and other utility lines below the FPE shall be constructed so as to prevent water from entering or accumulating within them during conditions of flooding.

H. Fully enclosed areas below the lowest floor that are subject to flooding shall be used only for parking, storage, or building access and 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 shall either be certified by a registered professional engineer or licensed architect and/or 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 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.

I. In zones V, V1-30 and VE, new structures and substantial improvements shall be elevated on pilings or columns so that:

1. The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated above the FPE.

2. 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 (one-hundred-year mean recurrence interval).

3. The areas below the lowest floor that are subject to flooding shall be free of obstruction.

4. The structure or improvement shall be located landward of the reach of mean high tide.

5. The use of fill for structural support of a structure or addition is prohibited.

6. 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 these provisions.

J. For 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, the lowest floor shall be at least two feet above the highest adjacent grade.

K. 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.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.270 Nonresidential construction.

New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection A or 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:

1. In AE and A1-30 zones or other A zoned areas where the base flood elevation data (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 at least one foot above the BFE, or as required by ASCE 24, whichever is greater.

2. If located in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the lowest floor shall be at least two feet above the highest adjacent grade.

3. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited or shall meet the requirements of TMC 18.38.260.

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

1. 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;

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

3. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice 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 TMC 18.38.180.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.280 Manufactured homes.

All manufactured homes to be placed or substantially improved on sites shall be:

A. Elevated on a permanent foundation in accordance with TMC 18.38.260; and

B. Securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement. Methods of anchoring may include, but are not to be limited to, use of over-the-top or frame ties to ground anchors, and shall be installed using methods and practices that minimize flood damage. This requirement is in addition to other applicable anchoring requirements for resisting wind forces.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.285 Detached accessory structures.

A. Detached accessory structures used solely for parking of vehicles or limited storage may be constructed such that the floor is below the base flood elevation (BFE), provided the structure is designed and constructed in accordance with the following requirements:

1. In special flood hazard areas other than coastal high hazard areas (zones A, AE, AH, AO, and A1-30), the structure is not larger than a one-story two-car garage;

2. In coastal high hazard areas (zones V, VE, V1-30, and VO), the structure is not larger than one hundred square feet in area;

3. The portions of the structure located below the BFE must be built using flood resistant materials;

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

5. Any machinery or equipment servicing the structure must be elevated or floodproofed to or above the BFE;

6. The structure must comply with floodway encroachment provisions in TMC 18.38.360(A)(1);

7. The structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with TMC 18.38.260(F);

8. The structure shall have low damage potential;

9. If the structure is converted to another use, it must be brought into full compliance with the standards governing such use; and

10. The structure shall not be used for human habitation.

(Ord. O2023-017, Added, 03/19/2024)

18.38.290 Recreational vehicles.

Recreational vehicles placed on sites shall:

A. Be on the site for fewer than one hundred eighty consecutive days; or

B. Be fully licensed and ready for highway use, on their 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 TMC 18.38.280.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.300 Appurtenant structures.

A structure which is on the same parcel of property as the principal structure and the use of which is incidental to the use of the principal structure and is not used for human habitation may be exempt from the elevation requirement of TMC 18.38.260(A), provided:

A. It is used only for parking or storage; and

B. It is constructed and placed on the building site so as to offer minimum resistance to the flow of floodwaters; and

C. It is anchored to prevent flotation which may result in damage to other structures; and

D. All portions of the structure below the FPE must be constructed of flood-resistant materials; and

E. Service utilities such as electrical and heating equipment meet the standards of TMC 18.38.260(E) and 18.38.310; and

F. It has openings to allow free flowage of water that meet the criteria in TMC 18.38.260(F); and

G. The project meets all the other requirements of this chapter, including TMC 18.38.320 through 18.38.400.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.310 Utilities.

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

B. Water wells shall be located outside the floodway and shall be protected to the FPE;

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

D. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. A habitat impact assessment shall be conducted in accordance with TMC 18.38.380 as a condition of approval of an on-site waste disposal system to be located in the special flood hazard area.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.320 Nondevelopment activities.

Activities that do not meet the definition of “development” are allowed in the special flood hazard area without the need for a floodplain development permit under this chapter, provided all other federal, state, and local requirements are met. The following are examples of activities not considered development or “manmade changes to improved or unimproved real estate”:

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

B. Removal of noxious weeds and hazard trees and replacement of nonnative vegetation with native vegetation;

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

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

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

F. 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 special flood hazard area 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; and

G. Plowing and other normal farm practices (other than structures or filling) on farms in the special flood hazard area and in existence as of the effective date of this chapter do not require a floodplain development permit. Clearing additional land for agriculture after the date of this chapter will require a floodplain development permit.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.325 Storage of materials and equipment.

A. The storage or processing of materials that could be injurious to human, animal, or plant life if released due to damage from flooding is prohibited in special flood hazard areas.

B. Storage of other material 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. O2023-017, Added, 03/19/2024)

18.38.330 Activities allowed with a floodplain permit.

The following activities are allowed in the special flood hazard area without the analysis required in TMC 18.38.360 or the habitat impact assessment required under TMC 18.38.380, providing all other requirements of this chapter are met, including obtaining a floodplain development permit:

A. Repairs or remodeling of an existing structure; provided, that the repairs or remodeling are not a substantial improvement or a repair of substantial damage.

B. Expansion of an existing structure that is no greater than ten percent beyond its existing footprint; provided, that the repairs or remodeling are not a substantial improvement or a repair of substantial damage. This measurement is counted cumulatively from the effective date of this chapter, or September 22, 2011, whichever is earlier. If the structure is in the floodway, there shall be no change in the dimensions perpendicular to flow.

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

D. Development of open space and recreational facilities, such as parks, trails, and hunting grounds, 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 special flood hazard area.

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

(Ord. O2015-007, Amended, 02/02/2016)

18.38.340 Other activities.

All other activities not listed in TMC 18.38.320 and 18.38.330 that are allowed by the underlying zoning are allowed, provided they meet all the other requirements of this chapter, including the analysis required in TMC 18.38.360 and the habitat impact assessment required under TMC 18.38.380, and a floodplain development permit is issued.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.350 Native vegetation.

The site plan required in TMC 18.38.140 shall show existing native vegetation.

A. In the riparian habitat zone, native vegetation shall be left undisturbed, except as provided in TMC 18.38.320 and 18.38.330(C).

B. Outside the riparian habitat zone, removal of native vegetation shall not exceed thirty-five percent of the surface area of the portion of the site in the special flood hazard area. Native vegetation in the riparian habitat zone portion of the property can be counted toward this requirement.

C. If the proposed project does not meet the criteria of subsections A and B of this section, a habitat impact assessment shall be conducted pursuant to TMC 18.38.380 and, if necessary, a habitat mitigation plan shall be prepared and implemented pursuant to TMC 18.38.390.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.360 Floodway standards.

A. In addition to the other requirements of this chapter, a project to develop in the floodway as delineated pursuant to TMC 18.38.100(E) and (F) or 18.38.120(D) shall meet the following criteria:

1. Encroachments, including fill, new construction, substantial improvements, and other development, are prohibited unless the applicant provides a certification by a registered professional engineer demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed development 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 repairs, reconstruction, or improvements to a residential structure which do not increase the ground floor area. The following exceptions must still meet all other requirements in the chapter, including subsection (A)(1) of this section:

a. Repairs, reconstruction, or improvements to a residential structure that do not increase the ground floor area, providing the cost of which does not exceed fifty percent of the market value of the structure either:

i. Before the repair or reconstruction is started; or

ii. If the structure has been damaged, and is being restored, before the damage occurred. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications that have been identified by a local code enforcement official, and which are the minimum necessary to assure safe living conditions, or to an historic structure, may be excluded from the fifty percent calculations;

b. Repairs, replacement, reconstruction, or improvements to existing farmhouses located in designated floodways and located on designated agricultural lands that do not increase the building’s total square footage of encroachment and are consistent with all requirements of WAC 173-158-075;

c. Repairs, replacement, reconstruction, or improvements to substantially damaged residential dwellings other than farmhouses that do not increase the building’s total square footage of encroachment and are consistent with all requirements of WAC 173-158-076; or

d. Repairs, reconstruction, or improvements to residential structures identified as historic structures that do not increase the building’s dimensions.

B. In riverine special flood hazard areas where a floodway has not been delineated pursuant to TMC 18.38.100(E) and (F) or 18.38.120(D), the applicant for a project to develop in the SFHA shall provide a certification by a registered professional engineer demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed development and all other past or future similar developments would not cumulatively result in an increase of flood levels during the occurrence of the base flood discharge by more than one foot.

C. If subsection (A)(1) of this section is satisfied or construction is allowed pursuant to subsection (A)(2) of this section, all new construction and substantial improvements in the floodway shall comply with all applicable flood hazard reduction provisions of this chapter.

(Ord. O2023-017, Amended, 03/19/2024; Ord. O2015-007, Amended, 02/02/2016)

18.38.370 Compensatory storage.

New development shall not reduce the effective flood storage volume of the special flood hazard area. A development proposal shall provide compensatory storage if grading or other activity eliminates any effective flood storage volume. Compensatory storage shall:

A. Provide equivalent volume at equivalent elevations to that being displaced. For this purpose, “equivalent elevation” means having similar relationship to ordinary high water and to the best available ten-year, fifty-year and one-hundred-year water surface profiles;

B. Be hydraulically connected to the source of flooding; and

C. Provide compensatory storage in the same construction season as when the displacement of flood storage volume occurs and before the flood season begins.

D. The newly created storage area shall be graded and vegetated to allow fish access during flood events without creating fish stranding sites.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.380 Habitat impact assessment.

Unless allowed under TMC 18.38.320 and 18.38.330, a permit application to develop in the special flood hazard area 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:

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

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

C. 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

D. An assessment prepared in accordance with Regional Guidance for Floodplain Habitat Assessment and Mitigation, FEMA Region X, 2013. The assessment shall determine if the project would adversely affect:

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

2. The primary constituent elements for critical habitat, when designated, including but not limited to water quality, water quantity, flood volumes, flood velocities, spawning substrate, and/or floodplain refugia for listed salmonids;

3. Essential fish habitat designated by the National Marine Fisheries Service;

4. Fish and wildlife habitat conservation areas;

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

(Ord. O2015-007, Amended, 02/02/2016)

18.38.390 Habitat mitigation plan.

A. If the assessment conducted under TMC 18.38.380 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 Regional Guidance for Floodplain Habitat Assessment and Mitigation, FEMA Region X, 2013.

1. If the USFWS or NMFS issues an incidental take permit under Section 10 of the ESA or a biological opinion under Section 7 of the ESA, then it can be considered to qualify as a plan to mitigate those impacts.

2. 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.

3. 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 are mitigated such that equivalent or better habitat protection is provided for the following functions:

a. Stormwater. Reduce flood volumes and stormwater runoff from new development by ensuring that increased volumes of stormwater reach the river at the same frequency, timing and duration as historical runoff. LID is required to be incorporated as described in TMC 18.38.220(B).

b. Riparian Vegetation. Maintain or replace riparian function by providing equivalent area, diversity, and function of riparian vegetation as currently exists on the site. Riparian retention requirements as outlined in TMC 18.38.350.

c. Hyporheic Zones. No activity is allowed that interferes with the natural exchange of flow between surface water, groundwater, and hyporheic zone; however, natural hyporheic exchange may be enhanced or restored.

d. Wetlands. Wetland function must be maintained or replaced by providing equivalent function.

e. Large Woody Debris. Any large woody debris (LWD) removed from the floodplain must be replaced in kind, replicating or improving the quantity, size, and species of the existing LWD.

4. No new stream crossings are allowed outside the protected area unless approval has been obtained as stated in subsection (A)(1) of this section.

B. 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.

C. As required in TMC 18.38.190, the floodplain administrator 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, in accordance with TMC 18.38.190(B).

(Ord. O2019-007, Amended, 09/03/2019; Ord. O2015-007, Amended, 02/02/2016)

18.38.400 Alteration of watercourses.

A. In addition to the other requirements in TMC 18.38.320 through 18.38.400, an applicant for a project that will alter or relocate a watercourse shall also submit a request for a conditional letter of map revision (CLOMR), where required by FEMA. The project will not be approved unless FEMA issues the CLOMR (which requires ESA consultation) and the provisions of the letter are made part of the permit requirements.

B. The floodplain administrator shall notify adjacent communities and the Washington Department of Ecology prior to any alteration or relocation of a watercourse, and submit evidence of such notification to FEMA.

C. Maintenance shall be provided within the altered or relocated portion of said watercourse so that the flood carrying capacity is not diminished. If the maintenance program does not call for cutting of native vegetation, the system shall be oversized at the time of construction to compensate for said vegetation growth or any other natural factor that may need future maintenance.

(Ord. O2015-007, Amended, 02/02/2016)

18.38.450 Penalties for noncompliance.

A. 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 constitute a misdemeanor. Nothing herein contained shall prevent the city of Tumwater from taking such other lawful action as is necessary to prevent or remedy any violation.

B. Enforcement under this section is in addition to and does not preclude or limit any other forms of enforcement available to the city including, but not limited to, enforcement under any provision of TMC Chapter 1.10, nuisance actions, actions for injunctions, or any other civil or equitable actions to abate, discontinue, or correct, acts in violation of this code.

(Ord. O2023-017, Added, 03/19/2024)