Chapter 17.125 CRITICAL AREAS – WETLANDS

Chapter 17.125
CRITICAL AREAS – WETLANDS – SPECIFIC STANDARDS

Sections:

17.125.010 Purpose.

17.125.020 Objectives.

17.125.030 Relationship to general standards for critical areas.

17.125.040 Wetland designation.

17.125.050 Classification of wetlands.

17.125.060 Standard buffer width requirements.

17.125.070 Building setbacks.

17.125.080 Critical area report – Specific requirements for wetlands.

17.125.090 Mitigation plan requirements.

17.125.100 Allowed permitted activities in streams, wetlands, and buffers.

17.125.110 Wetland mitigation bank credit.

17.125.010 Purpose.

It is the purpose of this chapter to promote the public health and general welfare by designating wetlands by definition and regulating development activity in these areas. Additionally, it is the intent of this chapter to adopt development regulations, required in RCW 36.70A.060, precluding land uses or development that is incompatible with critical areas designated under RCW 36.70A.170. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(1), 1995).

17.125.020 Objectives.

The objectives of this chapter are to:

(1) Protect human safety and health by minimizing adverse impacts of development;

(2) Enhance, preserve and protect unique, fragile and valuable wetlands through the application of best available science;

(3) Direct activities not dependent on wetland resources to less ecologically sensitive sites and mitigate unavoidable impacts to these critical areas by regulating alternations in and adjacent to them; and

(4) Implement the goals and policies of the Growth Management Act and the Stanwood Comprehensive Plan, as well as the requirements of the State Environmental Policy Act. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(2), 1995).

17.125.030 Relationship to general standards for critical areas.

This chapter contains standards specific to wetlands, and should be considered in conjunction with the standards in Chapter 17.114 SMC. Please refer to that chapter for general standards and administration. In the event of a conflict, the standards of this chapter shall prevail. (Ord. 1164 § 4, 2004).

17.125.040 Wetland designation.

Wetlands are those areas, designated in accordance with the Washington State Wetland Identification and Delineation Manual (Department of Ecology Publication #96-94), that are inundated or saturated by surface or groundwater 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. All areas within the city of Stanwood that meet the wetland designation criteria in the Identification and Delineation Manual, regardless of any formal identification, are hereby designated critical areas and are subject to the provisions of this chapter. (Ord. 1164 § 4, 2004).

17.125.050 Classification of wetlands.

All determinations of wetlands ratings and a wetlands delineation must be made based on the entire extent of the wetlands, unrelated to property lines or ownership patterns. Wetlands are classified based on the Washington State Wetland Rating System for Western Washington, as amended:

(1) Category I wetlands are wetlands that (1) represent a unique or rare wetland type; or (2) are more sensitive to disturbance than most wetlands; or (3) are relatively undisturbed and contain ecological attributes that are impossible to replace within a human lifetime; or (4) provide a high level of functions. Category I wetlands include the following:

(a) Estuarine wetlands greater than one acre;

(b) Natural heritage wetlands that are identified by the Natural Heritage Program as supporting state-listed threatened or endangered plants;

(d) Mature and old-growth forested wetlands;

(e) Wetlands in coastal lagoons; and

(f) Wetlands scoring 70 or higher based on functions in the Wetland Rating System.

(2) Category II wetlands are those that are difficult, though not impossible, to replace and provide high levels of some functions, including:

(a) Estuarine wetlands smaller than an acre or disturbed estuarine wetlands larger than an acre;

(b) Interdunal wetlands larger than one acre; and

(3) Category III wetlands include:

(a) Interdunal wetlands between one-tenth acre and one acre in size; and

(b) Wetlands scoring between 30 and 50 points based on functions in the Wetland Rating System.

(4) Category IV wetlands are those that have the lowest level of functions in the Wetland Rating System, scoring less than 30. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(3), 1995. Formerly 17.125.030).

17.125.060 Standard buffer width requirements.

Buffers shall be required for all wetlands regulated by this chapter. Required wetland buffer widths are as stated in this section.

(1) Required widths for wetland buffers are as follows:

(a) For Category I wetlands:


Category I Type	Buffer Width
Natural Heritage Wetlands	215 feet
Bog	215 feet
Estuarine	175 feet
Coastal Lagoon	175 feet
Habitat score from 29 to 36 points	225 feet
Habitat score from 20 to 28 points	150 feet
Category I not meeting any of the descriptions above	125 feet

(b) For Category II wetlands:


Category II Type	Buffer Width
Estuarine	135 feet
Habitat score from 29 to 36 points	200 feet
Habitat score from 20 to 28 points	125 feet
Category II not meeting any of the descriptions above	100 feet


Category III Type	Buffer Width
Habitat score from 20 to 28 points	125 feet
Category III not meeting any of the descriptions above	75 feet

(d) For Category IV wetlands: 50 feet.

(2) Measurement. The buffer shall be measured horizontally in a landward direction from the wetland edge. Where lands adjacent to a stream or wetland display a continuous slope of 25 percent or greater, the buffer shall include all such sloping areas. Where the horizontal distance of the sloping area is greater than the required standard buffer, the buffer shall be extended to a point 25 feet beyond the top of the bank of the sloping area.

(3) Increased Buffers.

(a) Priority Habitat Areas. If a Category I or II wetland with habitat score greater than 20 points is located within 300 feet of a priority habitat area as defined by the Washington State Department of Fish and Wildlife, the buffer established by subsection (1) of this section shall be increased by 50 feet unless:

(i) The applicant provides a relatively undisturbed vegetated corridor at least 100 feet wide between the wetland and all priority habitat areas located within 300 feet of the wetland. The corridor shall be protected for the entire distance between the wetland and the priority habitat through a conservation easement, native growth protection easement or the equivalent; and

(ii) The applicable mitigation measures in subsection (4) of this section are provided.

(b) Habitat for Endangered or Threatened Species, or Species of Local Importance. If the wetland contains documented habitat for endangered or threatened species, or species of local importance, the community development department shall establish the appropriate buffer based on a habitat assessment to ensure that the buffer provides adequate protection for the species.

(4) Reduced Buffer Widths.

(a) Averaging Buffer Widths. The width of a buffer may be averaged, thereby reducing the width of a portion of the buffer and increasing the width of another portion, if the community development director determines that all of the following requirements are met:

(i) The ecological structure and function of the buffer after averaging is equivalent to or greater than the structure and function before averaging;

(ii) The total area of the buffer after averaging is equivalent to or greater than the area of the buffer before averaging;

(iii) The additional buffer is contiguous with the standard buffer;

(iv) If the buffer averaging allows a structure or landscaped area to intrude into the original buffer, the resulting intrusion shall extend no more than 15 feet into the original buffer area; and

(v) No part of the width of the resulting buffer is less than 65 percent of the required buffer.

(b) Buffer Width Reduction. Buffer widths for all categories of wetlands may be reduced by 25 feet if the following mitigation measures are applied:


Disturbance	Activities That May Cause Disturbance	Measures to Minimize Impacts
Lights	Parking lots, warehouses, manufacturing, high density residential	Direct lights away from wetland
Noise	Manufacturing, high density residential	Place activity that generates noise away from wetland
Toxic Runoff	Parking lots, roads, manufacturing, residential areas, application of agricultural pesticides, landscaping	Route all new untreated runoff away from wetland; or covenants limiting use of pesticides within 150 feet of wetland; or integrated pest management program
Change in Water Regime	Any impermeable surface, lawns, tilling	Infiltrate or treat, detain and disperse runoff from impervious surfaces
Pets and Humans	Residential areas	Privacy fencing or landscaping to delineate buffer edge and to discourage disturbance of wildlife by humans and pets; and educational signage.
Dust	Tilled fields	Best management practices for dust control
Degraded Buffer	Existing degraded buffer condition	Non-native plants to be removed and replaced with native vegetation per an approved planting plan; and restoration to be bonded and monitored per SMC 17.114.250
Other as further defined by DOE wetlands guidance documents	Other as further defined by DOE wetlands guidance documents	Other as further defined by DOE wetlands guidance documents

(Ord. 1164 § 4, 2004; Ord. 1055, 1998; Ord. 929 Ch. 10(G)(4), 1995. Formerly 17.125.040).

17.125.070 Building setbacks.

Unless otherwise provided, buildings and other structures shall be set back a distance of 15 feet from the edges of all wetland buffer boundaries. The following may be allowed in the building setback area:

(1) Landscaping;

(2) Uncovered decks;

(3) Building overhangs if such overhangs do not extend more than 18 inches into the setback area; and

(4) Impervious ground surfaces, such as driveways and patios; provided, that such improvements may be subject to water quality regulations as adopted in Chapter 17.140 SMC. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(5), 1995. Formerly 17.125.050).

17.125.080 Critical area report – Specific requirements for wetlands.

A critical area report is required for any development activity allowed under this section and SMC 17.125.100. In addition to the general requirements of SMC 17.114.160, the following as part of the critical area study:

(1) A map drawn to scale or survey showing the following information:

(a) The edge of the wetland based on the Washington State Wetlands Identification and Delineation Manual as required by RCW 36.70A.175 (Ecology Publication #96-94);

(b) The wetlands characteristics and plant communities based on the U.S. Fish and Wildlife Service Classification of Wetlands and Deep Water Habitats in the U.S.;

(c) Stream corridors, name (if named), and stream type based on the State Department of Natural Resources’ Official Water Type Maps; and

(d) Observed or reported wildlife that make use of the area including, but not limited to, nesting, breeding, and feeding areas;

(2) A description of the streams and wetlands within 150 feet of the subject property, including buffers, drainage systems entering and leaving the site, a list of observed and documented plant and wildlife species, a description of the relative abundance of documented plant and wildlife species, and a description of the method used for flagging the wetlands edge, stream corridor, and buffers;

(3) A description and illustration of proposed development activities allowed under this section and SMC 17.125.100 within the wetlands or buffers;

(4) A description of any previous disturbances to the wetlands or buffers;

(5) A summary of the methodology used to conduct the study;

(6) A proposed classification of the wetlands based on SMC 17.125.050 and an explanation or rationale for the proposed rating;

(7) A mitigation plan which meets the requirements of SMC 17.125.090;

(8) A discussion of existing functional values of the wetland(s) and buffers;

(9) A discussion of the changes to wetland and buffer functional values resulting from the proposed development activity. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(6), 1995. Formerly 17.125.060).

17.125.090 Mitigation plan requirements.

(1) If alteration to a wetland or buffer is unavoidable, all adverse impacts to the wetland or buffer shall be mitigated in accordance with an approved critical area report. When mitigation is required by this chapter, it shall address restoration, rehabilitation, and compensation in accordance with SMC 17.114.180 and 17.114.190 and the following requirements:

(a) Wetland acreage shall be replaced at the following ratios when proposed on-site or off-site within the same subdrainage basin (“Stillaguamish floodplain”):

(i) Six to one (6:1) for category I wetlands;

(ii) Three to one (3:1) for category II wetlands;

(iii) Two to one (2:1) for category III wetlands; and

(iv) One and one-half to one (1.5:1) for category IV wetlands.

(b) The ratios in subsection (1)(a) of this section shall be doubled for off-site mitigation located outside the sub-basin (“Stillaguamish floodplain”), but within the larger mainstem Stillaguamish Basin. The ratios in subsection (1)(a) of this section shall also be doubled when mitigation proposes enhancement of an existing wetland. At a minimum a 1:1 replacement ratio shall be met first and enhancement may be utilized to meet ratio requirements beyond that.

(c) Inkind, on-site mitigation that is sufficient to achieve equivalent or greater critical area and/or buffer biologic functions and values is preferred so as to assure, to the greatest extent feasible, that the plan results in mitigation for direct impacts resulting from the alteration.

(d) Off-site mitigation will be used only in those situations where appropriate, adequate on-site mitigation is not feasible to achieve.

(2) The mitigation plan shall:

(a) Include a baseline study that analyzes the existing functional values of the wetlands and buffer, functional values that will be lost, and the system’s functional values after mitigation;

(b) Specify how lost functional values will be replaced;

(c) Specify when mitigation will occur relative to project construction and to the requirements of permits required by other jurisdictions;

(d) Address the need for and, when appropriate, determine the width of the buffer adjacent to any altered wetland edge; and

(e) In commercial or other public projects, provide interpretative signage at the rate of one per every five acres or portion thereof. The contents and design of the signage shall be approved by the planning director prior to installation. (Ord. 1164 § 4, 2004; Ord. 1110 § 3, 2002; Ord. 929 Ch. 10(G)(7), 1995. Formerly 17.125.070).

17.125.100 Allowed permitted activities in streams, wetlands, and buffers.

The following development activities may occur in wetlands and buffers:

(1) See SMC 17.114.140 for allowed activities. In addition to the provisions of that section, the following apply:

(a) Public and private pedestrian trails (in buffers only). In addition to the provisions of SMC 17.114.140(4)(e), trails proposed in wetland buffers shall be located in the outer 25 percent of the buffer area, the farthest distance from the wetland, and shall be constructed of pervious materials.

(2) Conservation, Preservation, Restoration and/or Enhancement. Restoration and/or enhancement of wetlands or their buffers; provided, that actions do not alter the location, dimensions or size of the wetland and/or buffer; that actions do not alter or disturb existing native vegetation or wildlife habitat attributes; that actions improve and do not reduce the existing functions of the wetland or buffer; and that actions are implemented according to a restoration and/or enhancement plan that has been approved by the city of Stanwood.

(3) Disturbance of Soils. When disturbance of soils is allowed in streams, wetlands or their buffers as part of an authorized, permitted activity or as otherwise allowed in these standards, the following shall apply:

(a) Disturbance of soils is allowed only during the dry season, which is typically regarded as beginning on May 1st and ending on October 1st of each year; provided, that the city of Stanwood may extend or shorten the dry season on a case-by-case basis, based on actual weather conditions.

(b) The soil duff layer in ungraded areas shall remain undisturbed to the maximum extent possible. Where feasible, any soil disturbed shall be redistributed to other nonwetland and stream areas of the project site.

(c) The moisture-holding capacity of the topsoil layer shall be maintained by minimizing soil compaction or reestablishing natural soil structure and infiltrative capacity on all areas of the project area not covered by impervious surfaces.

(d) Erosion and sediment control that meets or exceeds the standards set forth in the city of Stanwood’s stormwater regulations (Chapter 17.140 SMC) shall be provided.

(4) Public and Private Roadway Crossings, Bridges, and Culverts. Construction of public and private roadway crossings and bridges less than or equal to 30 feet wide and culverts less than or equal to 30 feet long, subject to the following standards:

(a) There is no other feasible alternative route with less impact on the wetland or buffer;

(b) Wetland crossings do not result in fill of greater than one-tenth of an acre of wetland; and

(5) Utility Lines. New utility lines may be permitted to cross wetlands and their buffers if they comply with the following standards:

(a) Critical areas and their buffers shall be avoided to the maximum extent feasible;

(b) Installation under a wetland shall be accomplished when feasible by boring beneath the wetland at a depth sufficient to prevent adverse hydrology impacts;

(d) Wetland crossings do not result in fill of greater than one-tenth of an acre of wetland; and

(e) Crossings shall be contained within the footprint of an existing street, driveway, or utility crossing where possible.

(6) Modification of Existing Structures. No existing structure may be modified to increase impervious surface in a wetland or buffer.

(7) In the event of a conflict between this section and SMC 17.114.140, this section shall apply. (Ord. 1164 § 4, 2004; Ord. 1110 § 3, 2002; Ord. 929 Ch. 10(G)(8), 1995. Formerly 17.125.080).

17.125.110 Wetland mitigation bank credit.

(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 Chapter 173-700 WAC;

(b) The community development director determines that the wetland mitigation bank provides appropriate compensation for the authorized impacts; and

(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, bank service areas may include portions of more than one adjacent drainage basin for specific wetland functions. (Ord. 1164 § 4, 2004; Ord. 929 Ch. 10(G)(9), 1995. Formerly 17.125.090).