Chapter 18.13
WETLANDS
Sections:
18.13.030 Contents of critical area reports.
18.13.040 Substantive requirements.
18.13.010 Designation.
Wetlands are those areas, designated in accordance with the Washington State Wetland Identification and Delineation Manual (1997), 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 Town of Wilkeson has a map, Figure 1, showing the approximate location and extent of wetlands. However, the map is only a guide, and will be updated, as wetlands 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. 2006.07 § 3, 2006; Ord. 2005.13 § 1 (Exh. 1), 2005].
18.13.020 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 #04-06-014). (See WAC 365-190-080(1)(a).) Wetland categories shall apply to the wetland, as it exists on the date the Town 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. 2006.07 § 3, 2006; Ord. 2005.13 § 1 (Exh. 1), 2005].
18.13.030 Contents of critical area reports.
In addition to the requirements of WMC 18.12.090, critical area reports for wetlands shall include:
A. Wetland delineation map as surveyed in the field. Buffer boundaries shall be marked in the field by a licensed surveyor using wood or steel posts, four (4) to five (5) feet tall above the ground surface, permanently affixed, carrying identification signs approved by the Town, to be obtained from the Town Hall. The charge for these signs shall be as set forth by resolution;
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 such as the Western Washington Wetland Rating System;
C. Discussion of measures to preserve wetland functions and values, including the “sequencing” set forth in WMC 18.12.130;
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;
4. Soils, substrate, and topography;
5. Required wetland buffers; and
6. Property ownership; and
E. Proposed wetland management and monitoring. [Amended during 2014 codification; Ord. 2006.07 § 3, 2006; Ord. 2005.13 § 1 (Exh. 1), 2005].
18.13.040 Substantive requirements.
In addition to the substantive requirements in WMC 18.12.130, the following requirements shall apply to developments (see definitions) in wetlands except as exempted above.
A. The higher the wetland category (Category I is highest), the greater shall be the emphasis on higher-priority “sequencing” methods per WMC 18.12.130.
B. The following table establishes the standard buffer width that shall apply to each wetland category, depending on the intensity of the potential land use on the upland side of the buffer as determined by the Director. Buffers shall be measured from the wetland boundary as surveyed in the field. These buffer widths presume that healthy native plant communities dominate the buffer. If wetland enhancement is proposed, the category of the wetland after enhancement shall pertain.
Wetlands Buffer Widths
|
|
Intensity of the potential land use on the upland side of the buffer |
||
|---|---|---|---|
|
|
High (including commercial areas, industrial areas, residential areas at more than four (4) units per net acre, and areas of high-intensity agriculture or recreation) |
Moderate (including residential areas at less than four (4) units per net acre, parks, and trails) |
Low (including passive recreation and open space) |
|
Category I |
300 feet |
250 feet |
200 feet |
|
Category II |
200 feet |
150 feet |
100 feet |
|
Category III* |
100 feet |
75 feet |
50 feet |
|
Category IV* |
50 feet |
35 feet |
35 feet |
*For exemption of wetlands less than 1,000 square feet see Wilkeson critical areas code.
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 Director may increase the required buffer width and/or require buffer enhancement if a wetland professional determines that the wetland provides habitat for wildlife species that require greater protection than the standard buffer, or the buffer lacks healthy native vegetation or is otherwise handicapped in its ability to protect the wetland. Said determination shall take into account the score derived from the wetland rating system and such factors as topography, land use, and past disturbance.
E. The Director may reduce the standard buffer width if the function(s) served by the particular wetland need less buffer width, as indicated by a wetland functional analysis.
F. 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 and bioswales are permitted in the outer fifty (50) percent of the buffer of Category III or IV wetlands provided wetland functions and values are not significantly lost through fluctuations in wetland hydrology and construction integrates best management practices. [Ord. 2006.07 § 3, 2006; Ord. 2005.13 § 1 (Exh. 1), 2005].
18.13.050 Mitigation.
A. Mitigation for alterations to wetlands may be by restoring former wetlands, creating wetlands, or enhancing degraded wetlands, consistent with the Department of Ecology Guidelines for Developing Freshwater Wetlands Mitigation Plans and Proposals, 2004, as revised.
B. Mitigation shall generally replace wetland functions lost from the altered wetland except that the Town 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 sub-basin 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. Mitigation projects shall be designed with reference to Wetland Replacement Ratios: Defining Equivalency, Washington Department of Ecology, 1992, Publication #92-08; Freshwater Wetlands in Washington State, Volume 2, Appendix 8-C; and similar science. Mitigation projects shall score the impact site and the mitigation site using the wetland rating data form of the Revised Washington State Wetlands Rating System for Western Washington. The aggregate total of wetland functions and values after mitigation, altered and mitigation sites combined, shall be at least fifty (50) percent greater than the aggregate total before mitigation; provided, that this replacement ratio (1.5-to-1, nonacreage-based) shall be increased as necessary to compensate for mitigation that:
1. Has a greater than usual risk of failure;
2. Is out-of-kind;
3. Is outside the sub-basin;
4. Is unlikely to produce the intended functions and values within ten (10) years after the alteration; or
5. Remedies unauthorized alterations.
F. Because the above replacement ratio is based on a before-and-after count of functions and values, not acreage, it accounts, without need for further adjustment, for mitigation that would result in a lower category wetland than the wetland being impacted, and mitigation that would enhance as opposed to create or restore a wetland. In the case of enhancement, wetland acreage may decline though wetland functions and values would increase. Enhancement proposals shall be based on a sound understanding of the mitigation site’s pre- and post-mitigation functions and values.
G. Credits granted from a certified wetland mitigation bank shall be consistent with the bank’s certification and service area.
H. The applicant shall provide an as-built plan of the mitigation site and monitor the site in accordance with WMC 18.12.110. [Ord. 2006.07 § 3, 2006; Ord. 2005.13 § 1 (Exh. 1), 2005].
