Chapter 23.20
WETLANDS
Sections:
23.20.030 Contents of critical areas reports.
23.20.040 Substantive requirements.
23.20.045 Buffers in shoreline jurisdiction.
23.20.060 Provisions for small wetlands within shoreline jurisdiction.
23.20.065 Provisions for small wetlands outside of shoreline jurisdiction.
23.20.070 Wetland buffer averaging.
23.20.010 Designation.
Wetlands are those areas, designated in accordance with the approved federal wetland delineation manual and applicable regional supplements, per WAC 173-22-035, that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation adapted for life in saturated soil conditions. The city has maps showing the approximate location and extent of wetlands. However, these maps are only a guide, and will be updated as critical areas become better known. The exact location of a wetland’s boundary shall be determined in accordance with the above-stated manual as required by RCW 36.70A.175 (Ecology Publication No. 96-94, 1997). (Ord. 2002 § 5 (Exh. C § 4), 2019; Ord. 1592 § 1, 2004).
23.20.020 Rating.
Wetlands shall be rated Category I, II, III, or IV according to the Department of Ecology’s 2004 Washington State Wetland Rating System for Western Washington (Publication No. 04-06-014). (See WAC 365-190-080(1)(a).) Wetland categories shall apply to the wetland as it exists on the date the city adopts the rating system, as the wetland naturally changes thereafter, or as the wetland changes in accordance with permitted activities. Wetland rating categories shall not change due to illegal modifications. (Ord. 1592 § 1, 2004).
23.20.030 Contents of critical areas reports.
In addition to the requirements of PMC 23.10.090, critical areas reports for wetlands shall include:
A. Wetland delineation map as surveyed in the field. Buffer boundaries shall be clearly and permanently marked in the field by a licensed surveyor using posts and signs approved by the city;
B. Assessment of wetlands, including acreage, category, required buffers, evidence of past illegal alterations, soil, topography, hydrology, ecology, and functional evaluation using a recognized method;
C. Discussion of measures to preserve wetland functions and values, including the sequencing set forth in PMC 23.10.130(E);
D. If mitigation is proposed, a mitigation plan including the existing and proposed status of:
1. Wetland acreage;
2. Vegetation and fauna;
3. Surface and subsurface hydrology;
5. Soils, substrate, and topography;
6. Required wetland buffers;
7. Property ownership; and
E. Proposed wetland management and monitoring. (Ord. 1592 § 1, 2004).
23.20.040 Substantive requirements.
In addition to the substantive requirements of PMC 23.10.130, the following requirements shall apply to wetlands; provided, that they shall not apply to existing and ongoing agricultural activities where the land has not lain idle so long that modifications to the hydrological regime are necessary to resume operations, nor to forest practice activities which are exempt from city jurisdiction.
A. The higher the wetland category (Category I is highest), the greater shall be the emphasis on higher-priority sequencing methods per PMC 23.10.130(E).
B. Standard buffer widths:
1. Outside of Shoreline Management Act jurisdiction shall be as specified below
a. Category I: 100 feet;
b. Category II: 50 feet;
c. Category III: 25 feet (exempt if smaller than 250 square feet; see PMC 23.10.070);
d. Category IV: 25 feet (exempt if smaller than 1,000 square feet; see PMC 23.10.070).
2. Within Shoreline Management Act jurisdiction: see PMC 23.20.045.
C. Buffers shall be measured from the wetland boundary as surveyed in the field. If wetland enhancement is proposed, the category of the wetland after enhancement shall pertain.
D. The above standard buffer widths presume that the adjoining upland land use is of urban density (at least four residential units per net acre or any commercial or industrial land use). The director may reduce the buffer widths if the adjoining upland land use is and will continue to be of low density, such as rural residential or passive parks.
E. Buffer Widths.
1. The above standard buffer widths presume that the buffer is moderately endowed with healthy native vegetation and other factors affecting its ability to protect the wetland, such as favorable topography.
2. The director 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.
3. The director 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.
4. Within Shoreline Management Act jurisdiction, the director’s decision must be processed according to the procedures and criteria in PMC Title 21 for a conditional use permit.
F. The director may increase or reduce the standard buffer width if the function(s) served by the particular wetland need more or less buffer width, as indicated by a wetland functional analysis. If a buffer reduction is granted by the director, the buffer at its narrowest point is never less than three-fourths of the required width except where an existing road or other existing barrier interrupts ecological functions; buffer conditions shall meet subsection (E)(2) or (E)(3) of this section. Within Shoreline Management Act jurisdiction, the director’s decision must be processed according to the procedures and criteria in PMC Title 21 for a conditional use permit.
G. Except as provided elsewhere in this 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 any mitigation bond. Stormwater management facilities, bioswales, and treated-water outfalls are permitted within the buffer, provided wetland functions and values are not significantly lost through fluctuations in wetland hydrology and construction integrates best management practices, and provided such facilities are within the outer 25 percent of the required buffer. Within Shoreline Management Act jurisdiction, additional regulations, criteria and procedures in PMC Title 21 apply. (Ord. 2002 § 5 (Exh. C § 5), 2019; Ord. 1592 § 1, 2004).
23.20.045 Buffers in shoreline jurisdiction.
A. Buffer Requirements. 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.
1. For wetlands that score six or more points for habitat function, the buffers in Table 23.20.045.1 can be used if both of the following criteria are met:
a. A relatively undisturbed, 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 latest definitions of priority habitats and their locations are available on the WDFW web site. The corridor must be protected for the entire distance between the wetland and the priority habitat by some type of legal protection such as a conservation easement.
Presence or absence of a nearby habitat must be confirmed by a qualified biologist. If no option for providing a corridor is available, Table 23.20.045.1 may be used with the required measures in Table 23.20.045.2 alone.
b. The measures in Table 23.20.045.2 are implemented, where applicable, to minimize the impacts of the adjacent land uses.
2. For wetlands that score three to five habitat points, only the measures in Table 23.20.045.2 are required for the use of Table 23.20.045.1.
3. If an applicant chooses not to apply the mitigation measures in Table 23.20.045.2, or is unable to provide a protected corridor where available, then Table 23.20.045.3 must be used.
4. The buffer widths in Tables 23.20.045.1 and 23.20.045.3 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 |
|
Category I: Based on Total Score |
75 |
110 |
225 |
|
Category I: Bogs and Wetlands of High Conservation Value |
190 |
225 |
|
|
Category I: Interdunal |
225 (buffer width not based on habitat scores) |
||
|
Category I: Forested |
75 |
110 |
225 |
|
Category I: Estuarine and Coastal Lagoons |
150 (buffer width not based on habitat scores) |
||
|
Category II: Based on Score |
75 |
110 |
225 |
|
Category II: Interdunal Wetlands |
110 (buffer width not based on habitat scores) |
||
|
Category II: Estuarine and Coastal Lagoons |
110 (buffer width not based on habitat scores) |
||
|
Category III (all) |
60 |
110 |
225 |
|
Category IV (all) |
40 |
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|
Disturbance |
Required Measures to Minimize Impacts |
|---|---|
|
Lights |
• 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 |
|
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 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 |
|
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Buffer width (in feet) based on habitat score |
||
|---|---|---|---|
|
Wetland Category |
3 – 5 |
6 – 7 |
8 –9 |
|
Category I: Based on Total Score |
100 |
150 |
300 |
|
Category I: Bogs and Wetlands of High Conservation Value |
250 |
300 |
|
|
Category I: Interdunal |
300 (buffer width not based on habitat scores) |
||
|
Category I: Forested |
100 |
150 |
300 |
|
Category I: Estuarine and Coastal Lagoons |
200 (buffer width not based on habitat scores) |
||
|
Category II: Based on Score |
100 |
150 |
300 |
|
Category II: Interdunal Wetlands |
150 (buffer width not based on habitat scores) |
||
|
Category II: Estuarine and Coastal Lagoons |
150 (buffer width not based on habitat scores) |
||
|
Category III (all) |
80 |
150 |
300 |
|
Category IV (all) |
50 |
||
(Ord. 2002 § 6 (Exh. C § 7), 2019).
23.20.050 Mitigation.
A. All mitigation shall be in accordance with the Washington State Wetlands Rating System for Western Washington – 2014 Update (Ecology Publication No. 14-06-029, October 2014), and the mitigation ratios and credit-debit method of the Wetland Guidance for CAO Updates: Western Washington Version (Ecology Publication No. 16-06-001, June 2016), Subsection XX.070, and subsections B through E of this section.
B. Mitigation shall generally replace wetland functions lost from the altered wetland except that the city may permit out-of-kind replacement when the lost functions are minimal or less important to the drainage basin than the functions that the mitigation action seeks to augment.
C. Mitigation shall be in the same drainage basin as the altered wetland. Wetland mitigation shall be in the same subbasin unless a higher level of ecological functioning would result from an alternate approach.
D. Mitigation projects shall be completed as quickly as possible consistent with such factors as rainfall and seasonal sensitivity of fish, wildlife, and flora.
E. Credits granted from a certified wetland mitigation bank shall be consistent with the bank’s certification and service area.
1. Credits from a wetland mitigation bank may be approved for use as compensation for unavoidable impacts to wetlands when:
a. The bank is certified under state rules;
b. The administrator determines that the wetland mitigation bank provides appropriate compensation for the authorized impacts; and
c. The proposed use of credits is consistent with the terms and conditions of the bank’s certification.
2. Replacement ratios for projects using bank credits shall be consistent with replacement ratios specified in the bank’s certification.
3. Credits from a certified wetland mitigation bank may be used to compensate for impacts located within the service area specified in the bank’s certification. In some cases, the service area of the bank may include portions of more than one adjacent drainage basin for specific wetland functions. (Ord. 2002 § 5 (Exh. C § 6), 2019; Ord. 1592 § 1, 2004).
23.20.060 Provisions for small wetlands within shoreline jurisdiction.
Within shoreline jurisdiction Category 4 wetlands of less than 4,000 square feet may be displaced; provided, that:
A. The wetlands are not associated with riparian areas or their buffers.
B. Are not part of a wetland mosaic.
C. Do not score six or more points for habitat function based on the 2014 update to the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by Ecology).
D. Do not contain a priority habitat or a priority area for a priority species identified by the Washington Department of Fish and Wildlife and do not contain federally listed species or their critical habitat.
E. Impacts are fully mitigated pursuant to PMC 23.20.050. (Ord. 2002 § 6 (Exh. C § 8), 2019).
23.20.065 Provisions for small wetlands outside of shoreline jurisdiction.
For wetlands not in shoreline jurisdiction, the following may be exempt from the requirement to avoid impacts, and they may be filled if the impacts are fully mitigated:
A. All isolated Category 4 wetlands less than 4,000 square feet that:
1. Are not associated with riparian areas or their buffers;
2. Are not associated with shorelines of the state or their associated buffers;
3. Are not part of a wetland mosaic;
4. Do not score six or more points for habitat function based on the 2014 update to the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by Ecology);
5. Do not contain a priority habitat or a priority area for a priority species identified by the Washington Department of Fish and Wildlife, do not contain federally listed species or their critical habitat, or species of local importance.
B. Wetlands less than 1,000 square feet that meet the above criteria and do not contain federally listed species or their critical habitat are exempt from the buffer provisions contained in this chapter. (Ord. 2002 § 6 (Exh. C § 9), 2019).
23.20.070 Wetland buffer averaging.
Within Shoreline Management Act jurisdiction, the director may average wetland buffer widths on a case-by-case basis when the applicant demonstrates through a wetland study to the satisfaction of the director that all the following criteria are met:
A. The wetland has significant differences in characteristics that affect its habitat functions, such as a wetland with a forested component adjacent to a degraded emergent component or a “dual-rated” wetland with a Category 1 area adjacent to a lower-rated area.
B. The buffer is increased adjacent to the higher-functioning area of habitat or more sensitive portion of the wetland and decreased adjacent to the lower-functioning or less sensitive portion.
C. The total area of the buffer after averaging is equal to the area required without averaging and all increases in buffer dimension for averaging are generally parallel to the wetland edge.
D. The buffer at its narrowest point is never less than three-fourths of the required width except where an existing road or other existing barrier interrupts ecological functions.
E. Wetland buffer averaging to allow reasonable use of a parcel may be permitted when all of the following are met:
1. There are no feasible alternatives to the site design that could be accomplished without buffer averaging;
2. The averaged buffer will not result in degradation of the wetland’s functions and values as demonstrated by a wetland assessment study;
3. The total buffer area after averaging is equal to the area required without averaging and all increases in buffer dimension for averaging are generally parallel to the wetland edge; and
4. The buffer at its narrowest point is never less than three-fourths of the required width except where the director finds that there is an existing feature such as a roadway that limits buffer dimension, or an essential element of a proposed development such as access that must be accommodated for reasonable use and requires a smaller buffer. (Ord. 2002 § 6 (Exh. C § 10), 2019).