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In addition to the substantive requirements in SPMC 15.18.030, the following requirements shall apply to developments (see definition) in wetlands except as exempted above:

A. The higher the wetland category (Category I is highest), the greater shall be the emphasis on higher-priority “sequencing” methods per SPMC 15.18.130.

B. The following table establishes the standard buffer width that shall apply to each wetland category, depending on the intensity of the potential land use on the upland side of the buffer as determined by the director. Buffers shall be measured from the wetland boundary as surveyed in the field. These buffer widths presume that healthy native plant communities dominate the buffer. If wetland enhancement is proposed, the category of the wetland after enhancement shall pertain.

Wetlands Buffer Widths

Intensity of the potential land use on the inland side of the buffer

High (including commercial areas, industrial areas, residential areas at more than four units per net acre, and areas of high-intensity agriculture or recreation)

Moderate (including residential areas at less than four units per net acre, parks, and trails)

Low (including passive recreation and open space)

Category I

300 feet

250 feet

200 feet

Category II

200 feet

150 feet

100 feet

Category III*

100 feet

75 feet

50 feet

Category IV*

50 feet

35 feet

35 feet

*For exemption of wetlands less than 1,000 square feet see SPMC 15.18.070(S).

C. Buffers shall be measured from the wetland boundary as surveyed in the field. If wetland enhancement is proposed, the category of the wetland after enhancement shall pertain.

D. The director may increase the required buffer width and/or require buffer enhancement if a wetland professional determines that the wetland provides habitat for wildlife species that require greater protection than the standard buffer, or the buffer lacks healthy native vegetation or is otherwise handicapped in its ability to protect the wetland. Said determination shall take into account the score derived from the wetland rating system and such factors as topography, land use, and past disturbance.

E. The director may reduce the standard buffer width if the function(s) served by the particular wetland need less buffer width, as indicated by a wetland functional analysis.

F. Except as provided elsewhere in this critical areas code, all existing native vegetation in wetland buffers shall be retained without disturbance, mowing, or hard surfacing, nor shall any action be taken to inhibit volunteer regrowth of native vegetation. Invasive weeds shall be removed for the duration of any mitigation bond. Storm water management facilities and bioswales are permitted in the outer 50 percent of the buffer of Category III or IV wetlands provided wetland functions and values are not significantly lost through fluctuations in wetland hydrology and construction integrates best management practices. [Ord. 492 § 3 (Exh. B § 124), 2007.]