14.162.080 Protection standards – Establishing buffers.
A. Requirements. The buffer widths in Table 14.1 have been established in accordance with the best available science. They are based on the category of wetland and the habitat score as determined by a qualified wetland professional using the Washington State Wetland Rating System for Western Washington.
1. The use of the buffer widths in Table 14.1 requires the implementation of the measures in Table 14.2, where applicable, to minimize the impacts of the adjacent land uses.
2. If an applicant chooses not to apply the mitigation measures in Table 14.2, then a 33 percent increase in the width of all buffers is required. For example, a 75-foot buffer with the mitigation measures would be a 100-foot buffer without them.
3. The buffer widths in Table 14.1 assume that the buffer is vegetated with a native plant community appropriate for the ecoregion. If the existing buffer is unvegetated, sparsely vegetated, or vegetated with invasive species that do not perform needed functions, the buffer should either be planted to create the appropriate plant community, or the buffer should be widened to ensure that adequate functions of the buffer are provided.
4. The buffer at its narrowest point is never less than either three-quarters of the required width or 75 feet for Category I and II, 50 feet for Category III and 25 feet for Category IV, whichever is greater.
|
Buffer width (in feet) based on habitat score |
||||
|---|---|---|---|---|
|
Wetland Category |
3-4 |
5 |
6-7 |
8-9 |
|
Category I: Based on total score |
75 |
105 |
165 |
225 |
|
Category I: Bogs and wetlands of high conservation value |
190 |
225 |
||
|
Category I: Coastal lagoons |
150 |
165 |
225 |
|
|
Category I: Interdunal |
225 |
225 |
||
|
Category I: Forested |
75 |
105 |
165 |
225 |
|
Category I: Estuarine |
150 (buffer width not based on habitat scores) |
|||
|
Category II: Based on score |
75 |
105 |
165 |
225 |
|
Category II: Interdunal wetlands |
110 |
165 |
225 |
|
|
Category II: Estuarine |
110 (buffer width not based on habitat scores) |
|||
|
Category III (all) |
60 |
105 |
165 |
225 |
|
Category IV (all) |
40 |
|||
|
Disturbance |
Required Measures to Minimize Impacts |
|---|---|
|
Light |
• 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 outer wetland buffer |
|
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 (for more information refer to the drainage ordinance and manual) |
|
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 conservation easement |
|
Dust |
• Use best management practices to control dust |
|
Disruption of corridors or connections |
• Maintain connections to off-site areas that are undisturbed • Restore corridors or connections to off-site habitats by replanting |
B. Buffer widths may be modified by averaging, reducing, or increasing.
1. Buffer width averaging may be allowed only where the applicant demonstrates the following:
a. Buffer encroachment is unavoidable.
b. A habitat assessment has been submitted which demonstrates that the site does not provide habitat for any endangered, threatened, or sensitive fish or animal species; or
c. For wetlands and/or required buffers associated with documented habitat for endangered, threatened, or sensitive fish or wildlife species, a habitat assessment report has been submitted that demonstrates that the buffer modification will not result in an adverse impact to the species of study.
d. The wetland contains variations in sensitivity due to existing physical characteristics; and
e. Width averaging will not adversely impact the wetland or critical fish and wildlife habitat; and
f. The total buffer area after averaging is no less than the buffer area prior to averaging; and
g. The minimum buffer width will not be less than 75 percent of the widths established in subsection A of this section.
h. The averaging is accomplished within the project boundaries.
i. Buffer width averaging shall only be permitted where it is shown that there are no feasible alternatives to the site design that could be accomplished without buffer averaging.
2. Buffer width reduction may be allowed only where the applicant demonstrates the following circumstances. Such reduction shall not result in greater than a 25 percent reduction in the buffer width established in subsection A of this section and shall result in a buffer no less than 30 feet in any case.
a. The proposed buffer area is extensively vegetated and has less than 15 percent slopes, and the reduction will not result in adverse impacts to the wetland; or
b. The project includes a buffer enhancement plan, as part of the mitigation required by LMC 14.162.100. The buffer enhancement plan shall use plant species which are indigenous to the project area, and shall substantiate that an enhanced buffer will improve the functional attributes of the buffer to provide additional protection for wetland functional values; or
c. The acreage included in the buffer would substantially exceed the size of the wetland and the reduction will not result in adverse impacts to the wetland or the project includes a buffer enhancement plan which ensures that the reduction will not result in adverse impacts to the wetland.
3. The Department may require increased buffer width when a larger buffer is necessary to protect wetland functions and values based on local conditions. This determination shall be reasonably related to protection of the functions and values of the regulated wetland. Such determination shall demonstrate that:
a. A larger buffer is necessary to maintain viable populations of existing species; or
b. The wetland is used by species listed by the federal government or the state as endangered, threatened, sensitive or as documented priority species or habitats, or essential or outstanding potential sites such as heron rookeries or raptor nesting areas; or
c. The adjacent land is susceptible to severe erosion and erosion control measures will not effectively prevent adverse wetland impacts; or
d. The adjacent land has minimal vegetative cover or slopes greater than 15 percent.
C. Buffers shall be measured perpendicular from the wetland edge.
D. When buffer boundaries have been determined, they shall be marked in the field by a licensed surveyor. The markers shall be clearly visible, durable, and permanently affixed to the ground.
E. A building setback line of eight feet shall be required from the edge of a buffer.
F. Except as otherwise specified, buffers shall be retained in a natural condition.
G. A wetland buffer shall not be required to extend beyond an existing substantial improvement such as an improved road, dike, levee, or a permanent structure, where the existing improvement obviates the beneficial impact that the buffer would provide for the wetland. [Ord. 630 § 8, 2015; Ord. 362 § 3, 2004.]