16.10.090 Buffer areas and setbacks

16.10.090 Buffer areas and setbacks.

A. General Provisions. The establishment of on-site buffers, buffer areas or setbacks shall be required for all development proposals and activities in or adjacent to wetlands, streams, wildlife habitat, and geologically hazardous areas. The purpose of the buffer shall be to protect the integrity, function, value, and resources of the subject critical area (in the case of wetlands, streams, and/or wildlife habitat areas), and/or to protect life, property and resources from risks associated with development on unstable or critical lands (in the case of geologically hazardous areas). Buffers shall typically consist of an undisturbed area of native vegetation retained or established to achieve the purpose of the buffer. No buildings or structures shall be allowed within the buffer unless as otherwise permitted by this section. If the site has previously been disturbed, the buffer area shall be revegetated pursuant to an approved enhancement plan. Buffers shall be protected during construction by placement of a temporary barricade, notice of the presence of the critical area and implementation of appropriate erosion and sedimentation controls. Restrictive covenants or conservation easements may be required to provide long-term preservation and protection of buffer areas.

B. Required buffer widths shall reflect the sensitivity of the particular critical area and resource or the risks associated with development and, in those circumstances permitted by these regulations, the type and intensity of human activity proposed to be conducted on or near the critical area.

C. Buffers shall be measured as follows:

1. Wetland buffers – the buffer shall be measured perpendicular from the wetland edge as delineated and marked in the field using the approved federal wetland delineation manual and the Western Mountains, Valleys, and Coast Regional supplement. Wetland delineations are valid for five years; after such date the city shall determine whether a revision or additional assessment is necessary;

2. Stream buffers – the buffer shall be measured perpendicular from the ordinary high water mark;

3. Geologically hazardous area buffers shall be required for critical landslide hazard areas and shall be measured from the top and toe and along the sides of the slope.

D. Buffer Width Variances. A variance from buffer width requirements may be granted by the city subject to the variance criteria set forth in ACC 16.10.160. Minor variances, defined as up to and including 10 percent of the requirement, shall be considered by the director. Variance requests which exceed 10 percent shall be considered by the hearing examiner.

E. Buffer widths shall be established for specific critical areas according to the following standards and criteria:

1. Wetland buffers shall be established per the following table. Different buffer width requirements may apply to various portions of a site, without requiring averaging or variances, based on the site plan, the intensity of land uses in various locations, and differences in the category of wetland.

Wetland Category	Minimum Buffer Width (in feet) with Minimization Measures Listed in ACC 16.10.090(E)(1)(a)(ii)			Minimum Buffer Width (in feet) without Minimization Measures Listed in ACC 16.10.090(E)(1)(a)(ii)
	Habitat Score*			Habitat Score*
	Low (3-5)	Medium (6-7)	High (8-9)	Low (3-5)	Medium (6-7)	High (8-9)
Category I	75	110	225	100	150	300
Category II	75	110	225	100	150	300
Category III	60	110	225	80	150	300
Category IV	40	40	40	50	50	50

*As determined per ACC 16.10.080(C).

a. Standard buffer widths as noted in subsection (E)(1) of this section in the table heading “without Minimization Measures” may be reduced to the buffer width in the table heading “with Minimization Measures,” if all of the following minimization measures are implemented and as follows:

i. For wetlands that score six points or more for habitat function, a relatively undisturbed, vegetated corridor at least 100 feet wide is protected between the wetland and any other Priority Habitats as defined by the Washington State Department of Fish and Wildlife. The corridor must be protected for the entire distance between the wetland and the Priority Habitat consistent with ACC 16.10.110(D). Presence or absence of a nearby habitat must be confirmed by a qualified biologist.

ii. For wetlands that score three to five habitat points, only the minimization measures are required.

Disturbance	Required Measures to Minimize Impacts
Lights	– Direct lights away from wetland
Noise	– Locate activity that generates noise away from wetland – If warranted, enhance existing buffer with native vegetation plantings adjacent to noise source – For activities that generate relatively continuous, potentially disruptive noise, such as certain heavy industry or mining, establish an additional 10-foot heavily vegetated buffer strip immediately adjacent to the activity
Toxic runoff	– Route all new, untreated runoff away from wetland while ensuring wetland is not dewatered – Establish covenants limiting use of pesticides within 150 feet of wetland – Apply integrated pest management
Storm water runoff	– Retrofit storm water detention and treatment for roads and existing adjacent development – Prevent channelized flow from lawns that directly enters the buffer – Use Low Intensity Development techniques
Change in water regime	– Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surfaces and new lawns
Pets and human disturbance	– Use privacy fencing or plant dense vegetation to delineate buffer edge and to discourage disturbance using vegetation appropriate for the ecoregion – Place wetland and its buffer in a separate tract or protect with a long-term conservation easement
Dust	– Use best management practices to control dust

b. Buffer averaging to improve wetland protection may be permitted when all of the following conditions are met:

i. The wetland has significant differences in characteristics that affect its habitat functions, such as a wetland with a forested component adjacent to a degraded emergent component or a “dual-rated” wetland with a Category I area adjacent to a lower-rated area.

ii. The buffer is increased adjacent to the higher-functioning area of habitat or more sensitive portion of the wetland and decreased adjacent to the lower-functioning or less sensitive portion as demonstrated by a critical areas report from a qualified wetland professional.

iii. The total area of the buffer after averaging is equal to the area required without averaging.

iv. The buffer at its narrowest point is never less than either 75 percent of the required width or 75 feet for Category I and II, 50 feet for Category III, and 25 feet for Category IV, whichever buffer is greater.

c. Certain uses and activities which are consistent with the purpose and function of the wetland buffer and do not detract from its integrity may be permitted by the director within the buffer depending on the sensitivity of the wetland. Examples of uses and activities with minimal impacts which may be permitted in appropriate cases include permeable pedestrian trails, viewing platforms, and utility easements. Trails and easements should be limited to minor crossings having no adverse impact on water quality. They should be generally parallel to the perimeter of the wetland, located only in the outer 25 percent of the wetland buffer area, and located to avoid removal of significant trees. Trails should be limited to pervious surfaces no more than eight feet in width for pedestrian use only. Raised boardwalks utilizing nontreated pilings may be acceptable.

d. Where existing buffers are degraded, the director may allow limited filling within the buffer when the applicant demonstrates that the buffer will be enhanced according to standards of this chapter, including appropriate soil preparation, will not result in slopes exceeding 25 percent, and there will be no net loss of wetland or buffer functions and values.

2. Stream buffers shall be established as follows:

Stream Type	Minimum Buffer Width (in feet)
Type S	Per SMP
Type F	100
Type Np	50
Type Ns	50

a. The applicable minimum buffer for Type S streams is listed in the city’s shoreline master program (SMP).

b. The buffer widths required in this section may be increased by the director up to a maximum of 50 percent for Type F and Ns streams and up to 100 percent for Type Np streams in response to site-specific conditions and based on the report information submitted to characterize the functions and values of the stream. This includes, but is not limited to, situations where the critical area serves as habitat for threatened, endangered or sensitive species. The applicant may propose to implement one or more enhancement measures, listed in order of preference below, which will be considered in establishing buffer requirements:

i. Removal of fish barriers to restore accessibility to anadromous fish.

ii. Enhancement of fish habitat using log structures incorporated as part of a fish habitat enhancement plan.

iii. Enhancement of wildlife habitat by adding structures that are likely to be used by wildlife, including wood duck houses, bat boxes, nesting platforms, snags, root wads/stumps, birdhouses, and heron nesting areas.

iv. Additional mitigating measures may include but are not limited to:

(A) Landscaping outside the buffer area with native vegetation or a reduction in the amount of clearing outside the buffer area;

(B) Planting native vegetation within the buffer area, especially vegetation that would increase value for fish and wildlife, increase stream bank or slope stability, improve water quality, or provide aesthetic/recreational value;

(D) Removing or modifying existing stream culverts (such as at road crossings) to improve fish passage and flow capabilities which are not detrimental to fish;

(E) Upgrading retention/detention facilities or other drainage facilities beyond required levels; or

(F) Similar measures determined applicable by the director.

c. No structures or improvements shall be permitted within the stream buffer area, including buildings, decks, docks, except as otherwise permitted or required under the city’s adopted shoreline master program, or under one of the following circumstances:

i. When the improvements are part of an approved enhancement, restoration or mitigation plan; or

ii. For construction of new public roads and utilities, and accessory structures, when no feasible alternative location exists; or

iii. Construction of foot trails, according to the following criteria:

(A) Designed to minimize impact of permeable materials;

(B) Designed to minimize impact on the stream system;

(D) Located within the outer half of the buffer, i.e., the portion of the buffer that is farther away from the stream; or

iv. Construction of footbridges; or

v. Construction of educational facilities, such as viewing platforms and informational signs.

d. Buffer width averaging may be allowed for Type F and Type Np streams only; provided, that all of the following are demonstrated by the applicant:

i. One or more of the enhancement measures identified in subsections (E)(2)(b)(i) through (E)(2)(b)(iv) of this section are implemented;

ii. The total area contained within the buffer after averaging is no less in area than contained within the standard buffer prior to averaging;

iii. The buffer width averaging will result in stream functions and values equal or greater than before averaging; and

iv. The buffer width is not reduced by more than 25 percent in any location than the buffer widths established by this chapter.

e. Stream buffer widths may be reduced by the director on a case-by-case basis by up to 25 percent if an applicant demonstrates that a reduction will not result in any adverse impact to the stream. Further, if an existing buffer is vegetated, a buffer enhancement plan may be required to demonstrate how the function and values of the buffer and stream will be improved. If the existing buffer has been disturbed and/or is not vegetated, an enhancement plan shall be required that identifies measures to enhance the buffer functions and values and provide additional protection for the stream function and values. Enhancement plans are subject to approval by the director.

a. Buffer widths for critical habitat areas shall be determined by the director based on consideration of the following factors: species recommendations of the Department of Fish and Wildlife; recommendations contained in the wildlife report and the nature and intensity of land uses and activities occurring on the site and on adjacent sites. Buffers shall not be required for secondary or tertiary habitat.

b. Buffer widths for critical habitat areas may be modified by averaging buffer widths or by enhancing or restoring buffer quality.

c. Certain uses and activities which are consistent with the purpose and function of the buffer for critical habitat areas and do not detract from its integrity may be permitted by the director within the buffer depending on the sensitivity of the habitat area. Examples of uses and activities with minimal impact which may be permitted in appropriate cases include permeable pedestrian trails and viewing platforms and utility easements; provided, that any impacts to the buffer resulting from permitted facilities shall be mitigated. When permitted, such facilities shall generally be located as far from the critical habitat area as possible.

a. Required buffer widths for geologically hazardous areas shall reflect the sensitivity of the geologically hazardous area in question and the types and the risks associated with development and, in those circumstances permitted by these regulations, the type and intensity of human activity and site design proposed to be conducted on or near the area.

b. Required buffers may vary in width. The widths of the buffer shall reflect the sensitivity of the geologically hazardous area in question and the types and density of uses proposed on or adjacent to the geologic hazard. In determining the appropriate buffer width, the director shall consider the recommendations contained in any geotechnical report required by these regulations and prepared by a qualified consultant.

c. Buffers may be reduced to a minimum width of 15 feet when the applicant demonstrates through the geotechnical report that the reduction will adequately protect the geologic hazard and the proposed development through use of proposed engineering techniques. (Ord. 6733 § 3 (Exh. B), 2019; Ord. 5894 § 1, 2005.)