Chapter 14.06
WETLAND CRITICAL AREAS1
Sections:
14.06.030 Permitted alterations.
14.06.010 Designation.
Identification of wetlands and delineation of their boundaries pursuant to this chapter shall be done in accordance with the approved federal wetland delineation manual and applicable regional supplement pursuant to RCW 36.70A.175. All areas within the city meeting the wetland designation criteria in that procedure are hereby designated critical areas and are subject to the provisions of this chapter.
Wetlands identified by the city and King County are shown on the map series associated with these amendments on file with the city. The map may be periodically revised by the city to add or remove areas based on additional information. The map is not a comprehensive map of all wetlands in North Bend and is to be used as a guide for the city, project applicants, and/or property owners. It is a reference and does not provide a final critical area designation.
For the purpose of categorization, wetlands shall be rated according to the Washington Department of Ecology wetland rating system, as set forth in the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029), or as revised and approved by Ecology, which contains the definitions and methods for determining whether the criteria set forth in this section are met.
A. Category I. (1) Relatively undisturbed estuarine wetlands larger than one acre; (2) wetlands of high conservation value that are identified by scientists of the Washington Natural Heritage Program/DNR; (3) bogs; (4) mature and old-growth forested wetlands larger than one acre; (5) wetlands in coastal lagoons; (6) interdunal wetlands that score eight or nine habitat points and are larger than one acre; and (7) wetlands that perform many functions well (scoring 23 points or more). These wetlands: (1) represent unique or rare wetland types; (2) are more sensitive to disturbance than most wetlands; (3) are relatively undisturbed and contain ecological attributes that are impossible to replace within a human lifetime; or (4) provide a high level of function.
B. Category II. Category II wetlands are: (1) estuarine wetlands smaller than one acre, or disturbed estuarine wetlands larger than one acre; (2) interdunal wetlands larger than one acre or those found in a mosaic of wetlands; or (3) wetlands with a moderately high level of functions (scoring between 20 and 22 points).
C. Category III. Category III wetlands are: (1) wetlands with a moderate level of functions (scoring between 16 and 19 points); (2) can often be adequately replaced with a well-planned mitigation project; and (3) interdunal wetlands between 0.1 and one acre. Wetlands scoring between 16 and 19 points generally have been disturbed in some ways and are often less diverse or more isolated from other natural resources in the landscape than Category II wetlands.
D. Category IV. Category IV wetlands have the lowest levels of functions (scoring fewer than 16 points) and are often heavily disturbed. These are wetlands that potentially could be replaced, or in some cases improved, although not guaranteed. These wetlands may provide some important functions and should be protected to the extent possible. (Ord. 1688 § 2 (Exh. B (part)), 2019).
14.06.020 Buffers.
Standard buffer widths presume the existence of a relatively intact native vegetation community in the buffer zone adequate to protect the wetland functions and values at the time of the proposed activity. If the vegetation is inadequate, then the buffer width shall be increased, or the buffer should be enhanced by planting or other means to maintain the standard functions and values for the required width. The following buffer widths 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: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by Ecology). The adjacent land use intensity is assumed to be high.
A. For all wetlands, the buffers in Table 14.06.020.1 can be used only when all of the measures in Table 14.06.020.2 are implemented, where applicable and feasible, to minimize the impacts of the adjacent land uses.
B. If an applicant chooses not to apply the mitigation measures in Table 14.06.020.2 to the extent determined reasonable and necessary by the city, then a 25 percent increase in the standard buffers provided in Table 14.06.020.1 may be required.
C. The buffer widths in Table 14.06.020.1 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.
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Buffer Width (in Feet) Based on Habitat Score |
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Wetland Category |
3 – 5 |
6 – 7 |
8 – 9 |
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Category I: Based on total score |
75 |
110 |
225 |
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Category I: Bogs and wetlands of high conservation value |
190 |
225 |
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Category I: Forested |
75 |
110 |
225 |
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Category II: Based on score |
75 |
110 |
225 |
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Category III (all) |
60 |
110 |
225 |
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Category IV (all) |
50 |
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Disturbance |
Required Measures to Minimize Impacts |
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Lights |
• Direct lights away from wetland |
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Noise |
• Locate activity that generates noise away from wetland • If warranted, enhance existing buffer with native vegetation plantings adjacent to noise source immediately adjacent to the wetland buffer |
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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 wetlands • Apply integrated pest management |
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Stormwater runoff |
• Retrofit stormwater detention and treatment for roads and existing adjacent development • Prevent channelized flow from lawns that directly enters the buffer • Use low impact development techniques (per PSAT publication on LID techniques) |
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Change in water regime |
• Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surfaces and new lawns |
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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 |
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Dust |
• Use best management practices to control dust |
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Disruption of corridors or connections |
The following measures are only required for wetlands with score for habitat functions greater than 5: • Maintain connections to off-site areas that are undisturbed • Restore corridors or connections to off-site habitats by replanting • Where other priority habitats as defined by the Washington State Department of Fish and Wildlife are located on the site or immediately off site, a relatively undisturbed, vegetated corridor at least 100 feet wide must be protected between the wetland and the other priority habitat (required for wetlands with 6 or more points for habitat functions; encourage for all other wetlands) |
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D. Measurement of Buffers. All buffers shall be measured from the critical area boundary as surveyed in the field. The width of the buffer shall be determined according to the category of the wetland rating and habitat score.
E. Any wetland created as compensation for an 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 an adjacent property, unless the same property owner owns the adjacent property or secures a native growth protection easement (NGPE) for the buffer on the adjoining property.
F. Averaging Buffers. The director will consider the allowance of wetland buffer averaging only when the buffer area width after averaging will not adversely impact the critical area and/or buffer functions and values. At a minimum, any proposed buffer averaging shall meet the following criteria:
1. The buffer area after averaging is no less than that which would be contained within the standard buffer;
2. The buffer width shall not be reduced by more than 25 percent at any one point as a result of the buffer averaging;
3. The additional buffer area shall be enhanced if necessary, to achieve no net loss of the critical areas functions and values;
4. The additional buffer is contiguous with the standard buffer;
5. Encroachment into the buffer does not occur waterward of the top of an associated steep slope or into a channel migration zone;
6. Encroachment does not occur into the buffer of an associated wetland except as otherwise allowed.
G. Increased Buffers. The director may require increased buffer sizes when a critical area report shows that it is necessary to protect the function and value of the critical areas when either the critical area is particularly critical to disturbance or the development poses unusual impacts. Examples of circumstances that may require buffers beyond minimum requirements include, but are not limited to:
1. Unclassified uses;
2. The critical area is a fish and wildlife habitat area for spawning or rearing as determined by the Washington State Department of Fish and Wildlife;
3. Land located within the development proposal that is adjacent to the critical area and its associated buffer is classified as an erosion hazard area; or
4. A trail or utility corridor in excess of 10 percent of the buffer width is proposed for inclusion in the buffer. (Ord. 1688 § 2 (Exh. B (part)), 2019).
14.06.030 Permitted alterations.
A. The requirements provided in this section supplement those identified in Chapter 14.05 NBMC. Activities and uses shall be prohibited from wetlands and wetland buffers, except that the following activities may be permitted only if the applicant can demonstrate that the activity will not degrade the functions and values of the wetland and other critical areas:
1. Conservation or preservation projects that will not change the structure or functions of the existing wetland; and
2. Projects which propose modifications to existing structures where no further alteration or increase in footprint will occur.
B. The director may require the preparation of a critical area report to confirm compliance with the requirements of this chapter.
C. Trails. Public and private trails may be allowed within wetland buffers where it can be demonstrated in a critical area report that the wetland and wetland buffer functions and values will not be degraded by trail construction or use, and that the location of the trail provides educational benefit to multiple users. Trail planning, construction, and maintenance shall adhere to the following criteria:
1. Permeable surface trail alignment generally shall be parallel to the perimeter of the wetland, located only in the outer 25 percent of the wetland buffer area, except as needed to access viewing platforms which may be located in the outer 50 percent of the wetland buffer, or as needed to cross the wetland. Trails may be placed on existing levees, railroad grades, or road grades within these limits;
2. Trails and associated viewing platforms shall be constructed of pervious materials no more than five feet in width for pedestrian use only, unless impervious surfaces are necessary for conformance to the Americans with Disabilities Act. Raised boardwalks utilizing nontreated pilings and decking may be acceptable for wildlife viewing platforms of no more than eight feet in width and totaling no more than 60 square feet of footprint, and for wetland crossings. The trail surface shall be limited to minor crossings having no adverse impact on water quality, and meet all other requirements, including water quality standards set forth in the current edition of the King County Surface Water Design Manual; and
3. Trail alignment shall avoid removal of trees to the greatest extent feasible, and shall provide mitigation for all unavoidable impacts.
D. Stormwater Management Facilities. A wetland or its buffer can be physically or hydrologically altered to meet the requirements of a LID for runoff treatment or flow control utilizing best management practices if all of the following criteria are met:
1. The wetland is classified as a Category IV or a Category III wetland with a habitat score of three to four points;
2. There will be “no net loss” of functions and values to the wetland;
3. The wetland does not contain a breeding population of any native amphibian species;
4. The hydrologic functions of the wetland can be improved as outlined in questions 3, 4, and 5 of Chart 4, and questions 2, 3, and 4 of Chart 5 in the “Guide for Selecting Mitigation Sites Using a Watershed Approach” (available at http://www.ecy.wa.gov/biblio/0906032.html); or the wetland is part of a priority restoration plan that achieves restoration goals identified in a shoreline master program or other local or regional watershed plan;
5. The wetland lies in the natural routing of the runoff, and the discharge follows the natural routing;
6. All regulations regarding stormwater and wetland management are followed, including but not limited to local and state wetland and stormwater codes, manuals, and permits; and
7. Modifications that alter the structure of a wetland or its soils will require permits. Existing functions and values that are lost shall be compensated/replaced.
E. Public Roads and Utilities. Normal and routine maintenance and repair of any existing public or private facility is allowed within an existing right-of-way; provided, that the maintenance or repair does not expand the footprint of the facility or right-of-way.
F. All isolated Category IV wetlands less than 4,000 square feet meeting criteria included in this subsection may be exempt from the mitigation sequencing requirement to avoid impacts, and may be filled when all impacts are fully mitigated as verified by the director. In order to verify the following conditions, a critical area report shall be required consistent with requirements in NMBC 14.05.240. An isolated Category IV wetland less than 4,000 square feet shall:
1. Not be associated with riparian areas or their buffers;
2. Not be associated with shorelines of the state or their associated buffers;
3. Not be part of a wetland mosaic;
4. Not score five or more points for habitat function based on the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by the Washington State Department of Ecology); and
5. Not contain (a) a priority habitat or a priority area for a priority species identified by the Washington Department of Fish and Wildlife, (b) federally listed species or their critical habitat, or (c) species of local importance as defined in Chapter 14.05 NBMC. (Ord. 1809 § 2, 2024; Ord. 1688 § 2 (Exh. B (part)), 2019).
Prior legislation: Ord. 1243.