Skip to main content

In addition to the substantive requirements of SMC 14.255.120, the requirements of this section shall apply to developments 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 SMC 14.255.120(E).

B. The following buffer width requirements are established as the minimum wetland buffer widths:

1. The standard buffer widths in this section are based on the fact that most impacts adjacent to wetlands in the City of Snohomish will be high intensity impacts characteristic of an urban area. Accordingly, one baseline buffer will generally apply to each category of wetland, as provided in subsection (B)(2) of this section, unless the habitat function score requires increasing the buffer width, as provided in subsection (B)(3) of this section, or unless the buffer width is increased, decreased, and/or averaged, as provided in subsections (D), (E), (F), and (G) of this section.

2. Standard/baseline buffer widths shall be:

Category I

150 feet

Category II

100 feet

Category III

50 feet

(exempt if smaller than 1,000 square feet: see SMC 14.255.060(S); between 1,000 square feet and 3,000 square feet in area shall be exempt from the normal sequencing process but shall be fully mitigated: see SMC 14.255.060(T))

Category IV

50 feet

(exempt if smaller than 1,000 square feet: see SMC 14.255.060(S); between 1,000 square feet and 3,000 square feet in area shall be exempt from the normal sequencing process but shall be fully mitigated: see SMC 14.255.060(T)

3. The standard/baseline buffer widths shall be increased for each category of wetland to the following wetland buffer widths, if the habitat function scores (derived from the 2004 Wetland Rating System for Western Washington) meet the following thresholds:

Category I

200 feet, if

habitat function score is at least 28

Category II

150 feet, if

habitat function score is at least 28

Category III

100 feet, if

habitat function score is at least 20

Category IV

50 feet, i.e.,

no increase regardless of habitat function score.

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

D. The above standard buffer widths presume the following:

1. The buffer is at least moderately endowed with healthy native vegetation (i.e., 75 percent ground cover) and other factors affecting its ability to protect the wetland, such as favorable topography.

2. The City Planner may increase the required buffer width or require buffer enhancement if the buffer is poorly endowed with healthy native vegetation or is otherwise handicapped in its ability to protect the wetland as specified in subsection (E) of this section.

3. The City Planner may reduce the required buffer width if the buffer is, or after enhancement will be, well-endowed with healthy native vegetation or otherwise unusually able to protect the wetland as specified in subsection (E) of this section.

E. The City Planner may increase or reduce the standard buffer width if the function(s) served by the particular wetland need(s) more or less buffer width, as indicated by a wetland functional analysis. Buffer widths may be reduced not more than 25 percent of the standard/baseline buffer width and only if restoration or enhancement occurs within the remaining buffer such that no net loss of function is realized.

F. The City Planner shall have the authority to average buffer widths on a case-by-case basis, where a qualified professional demonstrates to the City Planner’s satisfaction that all the following criteria are met:

1. The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer.

2. The buffer averaging does not reduce the functions or values of the wetland.

3. The wetland contains variations in sensitivity due to existing physical characteristics or the character of the buffer varies in slope, soils, or vegetation.

4. The director shall have the authority to increase the minimum width of the standard buffer on a case-by-case basis when such increase is necessary.

5. Buffer width averaging does not reduce the original buffer width by more 50 percent at any one point.

G. The City Planner may combine the use of buffer restoration or enhancement to reduce buffer width, as provided in subsection (E) of this section, with the use of buffer width averaging, as provided in subsection (F) of this section; provided, that there is no net loss of function and the original buffer width is not reduced by more than 50 percent at any one point.

H. Except as provided elsewhere in the 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 the monitoring period. Stormwater management facilities, bioswales, low impact development facilities, and treated-water outfalls are permitted in the outer 50 percent of the buffer of Category II, III or IV wetlands; provided, that wetland functions and values are not significantly lost through fluctuations in wetland hydrology and construction integrates best management practices. (Ord. 2315, 2016)

Loading…