18E.30.060 Buffer Requirements.
A. Determining Buffer Widths. Buffer widths shall be measured horizontally from a perpendicular line established at the wetland edge based on the Base Buffer Width identified in Table 1 and adjustments in Appendix F:
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Table 1 |
|
|---|---|
|
Generalized Category of Wetland |
Base Buffer Width |
|
Category I |
150 feet |
|
Category II |
100 feet |
|
Category III |
50 feet |
|
Category IV |
25 feet |
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Table 2. Land Use Impact "Intensity" Based on Development Types |
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|---|---|
|
Rating of impact from proposed changes in land use |
Types of land uses that cause the impact based on common zoning categories |
|
High |
Commercial, Urban, Industrial, Institutional, Retail Sales, Residential with more than 1 unit/acre, New agriculture (high- intensity processing such as dairies, nurseries and green houses, raising and harvesting crops requiring annual tilling, raising and maintaining animals), High intensity recreation (golf courses, ball fields), hobby farms |
|
Moderate |
Residential with 1unit/acre or less, Moderate-Intensity Open Space (parks), New agriculture (moderate-intensity such as orchards and hay fields) |
|
Low |
Forestry, Open space (low-intensity such as passive recreation and natural resources preservation) |
B. Modification of Buffer Widths. The standard buffer widths of PCC 18E.30.060 A. may be decreased through the averaging or reduction mechanisms of this Section. The standard buffer width may also be increased.
1. Standard Conditions. The buffer widths recommended for land uses with "high intensity" impacts to wetlands can be reduced to those recommended for "moderate intensity" impacts under the conditions identified below.
a. For wetlands that score moderate or high for habitat (20 points or more), the width of the buffer around the wetland can be reduced if both the following conditions are met:
(1) A relatively undisturbed native, 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 via some type of legal protection such as a conservation easement; and
(2) Measures to minimize the impacts of different land uses on wetlands, as summarized in the following table, are applied.
|
Examples of Disturbance |
Examples of Measures to Minimize Impacts |
Activities that Cause the Disturbance |
|---|---|---|
|
Lights |
Direct lights away from wetland |
Parking Lots, Warehouses, Manufacturing, High Density Residential |
|
Noise |
Place activity that generates noise away from the wetland. |
Manufacturing, High Density Residential |
|
Toxic runoff |
Route all new untreated runoff away from wetland, Covenants limiting use of pesticides within 150 feet of wetland Integrated pest management programs |
Parking Lots, Roads, Manufacturing, Residential Areas, Application of Agricultural Pesticides, Landscaping |
|
Change in water regime |
Infiltrate or treat, detain and disperse into buffer new runoff from surfaces |
Any impermeable surface, Lawns, Tilling |
|
Pets and Human disturbance |
Fence around buffer Plant buffer with "impenetrable" natural vegetation appropriate for region |
Residential areas |
|
Dust |
BMPs for dust |
Tilled fields |
b. For wetlands that score less than 20 points for habitat, the buffer width can be reduced to those required for moderate land use impacts if measures to minimize the impacts of different land uses on wetland as summarized in the table above in PCC 18E.30.060 B.1.
2. Buffer Averaging. Buffer width averaging may be allowed only where the applicant demonstrates all of the following:
a. The decrease in buffer width is minimized by limiting the degree or magnitude of the regulated activity.
b. A habitat assessment has been submitted which demonstrates that no documented habitat for endangered, threatened, or sensitive fish, or animal species is present; 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. Width averaging will not adversely impact the wetland.
e. The total buffer area after averaging is no less than the buffer area prior to averaging. (See Figure 18E.30-4.)
f. The minimum buffer width will not be less than 75 percent of the widths established after the categorization is done and any buffer adjustments applied.
g. The averaging is accomplished within the project boundaries or through an off-site conservation easement or tract (or other acceptable protective mechanism) approved by the Department.
3. Buffer Increases. The Department may require increased buffer width(s) when any of the following are identified:
a. A larger buffer is necessary to maintain viable populations of existing species;
b. The wetland is used by, or associated with, 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;
c. The adjacent land is susceptible to severe erosion and erosion control measures will not effectively prevent adverse wetland impacts;
d. The adjacent land has minimal vegetative cover or slopes greater than 20 percent.
C. If buffer width averaging is utilized and significant trees are identified on the outer edge of the reduced buffer such that their drip line extends beyond the buffer edge, the following tree protection requirements must be followed:
1. A tree protection area shall be designed to protect each tree or tree stand during site development and construction. Tree protection areas may vary widely in shape, but must extend a minimum of 5 feet beyond the existing tree canopy area along the outer edge of the dripline of the tree(s), unless otherwise approved by the Department.
2. Tree protection areas shall be added and clearly labeled on all applicable site development and construction drawings, submitted to the Department.
3. Temporary construction fencing at least 30 inches tall shall be erected around the perimeter of the tree protection areas prior to the initiation of any clearing or grading. The fencing shall be posted with signage clearly identifying the tree protection area. The fencing shall remain in place through site development and construction.
4. No clearing, grading, filling or other development activities shall occur within the tree protection area, except where approved in advance by the Department and shown on the approved plans for the proposal.
5. No vehicles, construction materials, fuel, or other materials shall be placed in tree protection areas. Movement of any vehicles within tree protection areas shall be prohibited.
6. No nails, rope, cable, signs, or fencing shall be attached to any tree proposed for retention.
7. The Department may approve the use of alternate tree protection techniques if an equal or greater level of protection will be provided.