A. Required wetland buffer widths shall reflect the natural functions and values of the wetland, the sensitivity of the area and resource, and the risks associated with development. In addition, 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 wetland shall be reflected in the required buffer width. Standard buffer widths presume the existence of a relatively intact native vegetation community in the buffer zone adequate to protect wetland functions and values at the time of the proposed activity. If vegetation is inadequate, the buffer width shall be increased or the buffer planted with appropriate vegetation to maintain the standard width to meet needed buffer functions.
B. Small Wetlands Exempt from Buffer Requirements.
1. Wetlands are exempt from buffer requirements if they are less than 1,000 square feet in area, and it has been shown by the applicant that they:
a. are not associated with a riparian corridor;
b. are not part of a wetland mosaic; and
c. do not contain habitat identified as essential for local populations of priority species identified by Washington Department of Fish and Wildlife.
2. The requirement to avoid impacts pursuant to mitigation sequencing, may be dropped for Category 3 and 4 wetlands between 1,000 and 4,000 square feet that meet all of the following criteria:
a. Wetland is not associated with a riparian corridor;
b. Wetland is not part of a wetland mosaic;
c. Wetland does not score 5 points or greater for habitat in the 2014 Western Washington Rating System; and
d. Wetland does not contain habitat identified as essential for local populations of priority species identified by Washington Department of Fish and Wildlife.
3. Impacts allowed under this provision to these wetlands will be fully mitigated as required in mitigation Section 13-4-7.
C. The standard wetland buffer width shall apply for wetlands not found exempt under Section 13-4-4(B), except in cases where, pursuant to the buffer width reduction provisions in Section 13-3-12-(C)(4) of this title, the Director determines the standard wetland buffer width may be reduced up to a maximum of twenty five percent (25%) for high intensity land uses only, provided the applicant meets all other provisions of this chapter and can demonstrate through a wetlands report based on best available science that a smaller area is adequate to protect wetland functions, and the proposal includes all applicable following measures to minimize impacts:
1. Lights are directed away from the wetland;
2. Noise-generating activities are directed away from the wetland;
3. Infiltrate or treat, detain, and disperse runoff into the wetland from impervious surfaces;
4. Route all new untreated runoff away from the wetland while ensuring wetland is not dewatered;
5. Covenants limiting the use of pesticides within 150 feet of the wetland;
6. Utilize integrated pest management
7. Utilize privacy fencing or landscaping to delineate buffer edge and to discourage disturbance of wildlife by humans and pets;
8. Prevent flow from lawns from directly entering buffer;
9. Use low intensity development (LID)techniques;
10. Use privacy or native vegetative fencing to delineate buffer edge;
11. Protect wetland and its buffer with a conservation easement;
12. Use best management practices to control dust;
13. Maintain connections to offsite areas that are undisturbed;
14. Restore corridors or connections to offsite habitats by replanting;
15. Other measures further defined by DOE guidance documents.
D. Standard buffer widths shall be based upon wetland category, wetland functions or special characteristics, and/or the intensity of proposed adjacent land use and the level of wetland impact likely to result from that land use intensity. Required standard wetland buffers shall be as shown below.
TABLE 13-4.1
STANDARD WETLAND BUFFERS
DOE Manual Wetland Characteristics(1) | Standard Buffer Widths (based on Likely Level of Impact from Proposed Adjacent Land Use) | Other Measures Recommended for Protection |
DOE Manual Wetland Characteristics(1) | Standard Buffer Widths (based on Likely Level of Impact from Proposed Adjacent Land Use) | Other Measures Recommended for Protection |
Category I Wetlands | ||
Wetlands of High Conservation Value | Low-125' Moderate-190' High-250' | No additional surface water discharges to wetland or its tributaries No septic systems within 300 feet Restore degraded parts of buffer |
Bogs | Low-125' Moderate-190' High-250' | No additional surface water discharges to wetland or its tributaries Restore degraded parts of buffer |
Forested | Buffer size to be based on score for habitat functions or water quality functions | If forested wetland score high for habitat, need to maintain connectivity to other natural areas; restore degraded parts of the buffer |
Estuarine | Low-100' Moderate-150' High-200' | Reserved |
Habitat function level high | Low-150' Moderate-225' High-300' | Maintain connections to other habitat areas Restore degraded parts of buffer |
Habitat function level moderate | Low-75' Moderate-110' High-150' | Reserved |
Water quality improvement level high and habitat function level low | Low-50' Moderate-75' High-100' | No additional surface discharges of untreated runoff |
Not meeting any of the above characteristics | Low-50' Moderate-75' High-100' | Reserved |
Category II Wetlands | ||
Habitat function level high | Low-150' Moderate-225' High-300' | Maintain connections to other habitat areas |
Habitat function level moderate | Low-75' Moderate-110' High-150' | Reserved |
Water quality improvement level high and habitat function level low | Low-50' Moderate-75' High-100' | No additional surface discharges of untreated runoff |
Estuarine | Low-75' Moderate-110' High-150' | Reserved |
Interdunal wetlands > 1 acre and that score 6 or 7 habitat points | Low-50' Moderate-75' High-100' | Enhancement of interdunal wetlands as compensatory mitigation not allowed |
Interdunal wetlands > 1 acre and that score 5 or less | Low-40' Moderate-60' High-80' | Enhancement of interdunal wetlands as compensatory mitigation not allowed |
Not meeting any of the above characteristics | Low-50' Moderate-75' High-100' | Reserved |
Category III Wetlands | ||
Habitat function level moderate | Low-75' Moderate-110' High-150' | Reserved |
Interdunal wetlands (0.1 acre- 1 acre) | Low-40' Moderate-60' High-80' | Enhancement of interdunal wetlands as compensatory mitigation not allowed |
Not meeting any of the above characteristics | Low-40' Moderate-60' High-80' | Reserved |
Category IV Wetlands | ||
Score for all three basic wetland functions is less than 16 points Any interdunal wetland <0.1 acre | Low-25' Moderate-40' High-50' | Reserved |
Notes:
(1) Habitat and water quality function levels are based on scores from the Washington State Wetland Rating System for Western Washington.
Sources: Wetlands in Washington State, Volume 2, Protecting and Managing Wetlands, Modified Appendix 8-C for use with the 2014 Wetland Rating System (Guidance on Buffers and Ratios-Western Washington, April 2005 (Washington state Department of Ecology); City of Long Beach Dune Management Report, March 2000.
See also provisions of this code relating to increased and decreased buffer widths and buffer averaging.
Land use intensity (i.e., low, moderate, high) shall be determined using the table set forth below.
TABLE 13-4.2
LAND USE AND LIKELY LEVEL OF IMPACTS
Likely Level of Impact from Proposed Adjacent Land Use | Proposed Adjacent Land Use Types |
Likely Level of Impact from Proposed Adjacent Land Use | Proposed Adjacent Land Use Types |
High | • Commercial, including retail sales |
• Industrial | |
• Institutional | |
• Residential (more than one (1) d.u. per acre) | |
• High intensity recreation (e.g., golf courses) | |
• Hobby Farms | |
Moderate | • Residential (one (1) d.u. per acre or less) |
• Moderate intensity open space (parks) | |
• Paved trails | |
• Paved driveways and gravel driveways serving three (3) or more residences | |
Low | • Timber management |
• Low intensity open space (e.g., passive recreation, natural resources preservation) | |
• Unpaved trails | |
• Gravel driveways serving two (2) or fewer residences | |
• Utility corridor without a maintenance road and little or no vegetation management | |
D. Any wetland created as compensation for approved wetland alteration shall have the standard buffer required for the new classification of the created wetland. Wetlands to be created shall be located such that the new associated wetland buffer does not cross onto adjacent property, unless the same property owner owns the adjacent property or has obtained written permission from the adjacent property owner to do so.
E. Land-ward Residential Addition. For proposed development consisting of an expansion of an existing single family residential structure within a wetland buffer, for which the proposed expansion is on the land-ward side of the structure furthest from the wetland, no mitigation shall be required for such expansion, so long as the width of the expanded structure parallel to the wetland boundary is not increased. (Ord. 985, 10-5-2020)