19.37.120 Wetland alteration thresholds and compensation

19.37.120 Wetland alteration thresholds and compensation.

1. Category I Wetlands. All category I wetlands shall be preserved except as provided in this chapter. The planning director, using the review process as described in EMC Title 15, Local Project Review Procedures, may allow alteration of category I wetlands:

a. Where alteration is allowed pursuant to EMC 19.37.050; or

b. The alteration is to allow a public park or public recreational use; provided, that there is no feasible and reasonable alternative to making the alteration and the alteration does not act to degrade the functions of the wetland, or the alteration proposed has a reasonable likelihood of being fully mitigated;

2. Category II, III, and IV Wetlands. All category II, III, and IV wetlands shall be preserved except as provided in this chapter. The planning director, using the review process described in EMC Title 15, Local Project Review Procedures, may allow alteration of category II wetlands:

a. Where alteration is allowed pursuant to EMC 19.37.050; or

b. Where impacts cannot be avoided, and the applicant demonstrates through a mitigation sequencing analysis that reduction in the size, scope, configuration, or density of the project as proposed and all alternative designs of the project as proposed that would avoid or result in less adverse impact on a regulated wetland or its buffer are not feasible and will not accomplish the basic purpose of the project;

3. Category I, II, III, and IV Wetlands in the Silver Lake Watershed. When alteration of wetlands in the Silver Lake Watershed is allowed in subsections A.1 and A.2 of this section, the applicant must also demonstrate to the satisfaction of the planning director and public works director that such activities will result in an enhancement of wetlands which improves the water quality functions of the wetland, or will improve the other functions of the wetland if the water quality functions of the wetland will not be degraded. Any such proposed activities shall be reviewed using the review process described in EMC Title 15, Local Project Review Procedures;

4. The director may approve alteration of wetlands and buffers when proposed to restore or enhance wetland functions.

B. Compensating for Wetland Impacts. Wetland and buffer alteration allowed by this section shall be subject to the following requirements:

1. Each activity/use shall be designed so as to minimize overall wetland or buffer alteration to the greatest extent possible.

2. Construction techniques and field marking of areas to be disturbed shall be approved by the city prior to site disturbance to ensure minimal encroachment.

3. A mitigation plan shall be prepared in accordance with subsection C of this section.

4. The city may require the applicant to rehabilitate a wetland or its buffer by removing debris, sediment, nonnative vegetation, or other material detrimental to the area by replanting disturbed vegetation, or by other means deemed appropriate by the city. Rehabilitation or restoration may be required at any time that a condition detrimental to water quality or habitat exists.

5. Wetland Compensation Ratios. In approving alteration or relocation of a wetland, the city shall require that an area larger than the altered portion of the wetland be provided as compensation for destruction of the functions of the altered wetland and to ensure that such functions are replaced. The ratios in this section apply to creation, restoration, and enhancement which is in-kind (within the same hydrogeomorphic (HGM) class), on or adjacent to the site, timed prior to or concurrent with alteration, and has a high probability of success. The city may accept or recommend compensation which is off site and/or out-of-kind, if the applicant can demonstrate that on-site compensation is infeasible due to constraints such as parcel size or wetland type or that a wetland of a different type or location is justified based on regional needs or functions. When mitigating allowed impacts to wetlands, the standard ratios in Table 37.4 shall be used, except as otherwise provided below in this subsection.

Table 37.4: Standard Wetland Compensation Ratios
Category and Type of Wetland Impacts	Reestablishment or Creation	Rehabilitation Only¹	Reestablishment or Creation (R/C) and Rehabilitation (RH)¹	Reestablishment or Creation (R/C) and Enhancement (E)¹	Enhancement Only¹
All category IV	1.5:1	3:1	1:1 R/C and 1:1 RH	1:1 R/C and 2:1 E	6:1
All category III	2:1	4:1	1:1 R/C and 2:1 RH	1:1 R/C and 4:1 E	8:1
Category II Estuarine	Case-by-case	4:1 Rehabilitation of an estuarine	Case-by-case	Case-by-case	Case-by-case
All other category II	3:1	6:1	1:1 R/C and 4:1 RH	1:1 R/C and 8:1 E	12:1
Category I Forested	6:1	12:1	1:1 R/C and 10:1 RH	1:1 R/C and 20:1 E	24:1
Category I Based on score for functions	4:1	8:1	1:1 R/C and 6:1 RH	1:1 R/C and 12:1 E	16:1
Category I Bog	Not considered possible²	6:1 Rehabilitation of a bog	R/C Not considered possible²	R/C Not considered possible²	Case-by-case
Category I Estuarine	Case-by-case	6:1 Rehabilitation of an estuarine	Case-by-case	Case-by-case	Case-by-case
NOTE: Preservation is discussed in the following section.
Creation = The manipulation of the physical, chemical, or biological characteristics present to develop a wetland on an upland or deepwater site, where a wetland did not previously exist. Activities typically involve excavation of upland soils to elevation that will produce a wetland hydroperiod, create hydric soils, and support the growth of hydrophytic plant species. Establishment results in a gain in wetland acres.
Reestablishment = The manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural or historic functions to a former wetland. Activities could include removing fill material, plugging ditches, or breaking drain tiles. Activities could also involve breaching a dike to reconnect wetlands to a floodplain or return tidal influence to a wetland. Reestablishment results in a gain in wetland acres.
Rehabilitation = The manipulation of the physical, chemical, or biological characteristics of a site with the goal of repairing natural or historic function of a degraded wetland. Activities could involve breaching a dike or reconnecting wetland to a floodplain or returning tidal influence to a wetland. Rehabilitation results in a gain in wetland function but does not result in a gain in wetland acres.
Enhancement = The manipulation of the physical, chemical or biological characteristics of a wetland site to heighten, intensify or improve functions or to change the growth stage or composition of the vegetation present. Enhancement is undertaken for specified purposes such as water quality improvement, flood water retention or habitat. Activities typically consist of planting vegetation, controlling nonnative or invasive species, modifying the site elevation or the proportion of open water to influence hydroperiods, or some combination of these. Enhancement results in a change in some wetland functions and can lead to a decline in other wetland functions, but does not result in a gain in wetland acres.

1These ratios are based on the assumption that the rehabilitation or enhancement actions implemented represent the average degree of improvement possible for the site. Proposals to implement more effective rehabilitation or enhancement actions may result in a lower ratio, while less effective actions may result in a higher ratio. The distinction between rehabilitation and enhancement is not clear-cut. Instead, rehabilitation and enhancement actions span a continuum. Proposals that fall within the gray area between rehabilitation and enhancement will result in a ratio that lies between the ratios for rehabilitation and the ratios for enhancement.

2Bogs are considered irreplaceable wetlands because they perform some special functions that cannot be replaced through compensatory mitigation. Impacts to such wetlands would therefore result in a net loss of some functions no matter what kind of compensation is proposed.

a. Increased Mitigation Ratios. The city may increase the ratios under any one of the following circumstances:

(1) Uncertainty as to the probable success of the proposed restoration or creation;

(2) Significant period of time between destruction and replication of wetland functions;

(3) The proposed mitigation will result in a lower category wetland or projected losses in functions relative to the wetland being impacted;

(4) The relocation is off site or the replacement is with out-of-kind compensation;

(5) The wetland has been illegally filled or altered.

b. Decreased Mitigation Ratios. The city may decrease these ratios under the following circumstances:

(1) Documentation by a qualified wetland specialist demonstrates that the proposed mitigation actions have a very high likelihood of success.

(2) Documentation by a qualified wetland specialist demonstrates that the proposed mitigation actions will provide significantly greater functions than the wetland being impacted.

(3) The mitigation actions are conducted in advance of the impact and have been shown to be successful.

c. In lieu of the ratios described above, mitigation ratios may be calculated in one of the following ways:

(1) Using the method in Calculating Credits and Debits for Compensatory Mitigation in Wetlands of Western Washington: Final Report, March 2012, Washington State Department of Ecology Publication No. 10-06-011, or as amended.

(2) For properties designated “urban mixed-use industrial” in the city’s shoreline master program, the applicant shall use the Snohomish Estuary Wetland Integration Plan (SEWIP, 1997) and Salmon Overlay (2001) for projects that include wetland compensation. Per Table 37.4, mitigation ratios for estuarine wetlands shall be determined on a case-by-case basis.

d. In no case shall the mitigation acreage be less than that which is altered.

6. When wetland compensation is allowed, the city may require that the wetland compensation be completed and functioning prior to allowing the existing wetland to be filled or altered. For category I wetlands, the city shall require the relocated wetland area to be completed and functioning prior to allowing the existing wetland to be altered.

7. The city may limit certain development activities near a wetland to specific months in order to minimize impacts on wetland functions.

8. The city may apply additional conditions or restrictions or require specific construction techniques in order to minimize impacts on wetland functions.

9. Wetland compensation shall not occur in areas having high-quality terrestrial habitat.

10. When wetland compensation is allowed, mitigation areas shall be located to preserve or achieve contiguous wildlife habitat corridors to minimize the isolation and fragmenting effects of development on habitat areas.

11. When wetland creation is proposed, all required buffers for the creation site shall be located on the proposed creation site, except where mitigation banking is used to purchase buffer credits. Properties adjacent to or abutting wetland creation projects shall not be responsible for providing any additional buffer requirements.

12. In-Lieu Fee Mitigation. In-lieu fee (ILF) mitigation is a program involving the restoration, establishment, enhancement, and/or preservation of aquatic resources through funds paid to a program sponsor to satisfy compensatory mitigation requirements for unavoidable impacts to wetlands and other aquatic resources. Per federal rule, sponsorship of ILF programs is limited to governmental, tribal, or nonprofit natural resource management entities. Similar to a wetland mitigation bank, an ILF program sells credits to permittees whose unavoidable impacts occur within a specified geographic area (service area). When credits are purchased from the ILF program, the permittee’s obligation to provide compensatory mitigation is then transferred to the ILF program sponsor. The sponsor is then required to implement mitigation within a specified time frame, working with regulatory agencies to make sure impacts are fully mitigated. ILF programs are approved by the U.S. Army Corps of Engineers and the Washington State Department of Ecology. The city may allow compensation for unavoidable impacts to wetlands through contribution to an approved ILF program.

C. Wetland and Buffer Mitigation Plans. When wetland or buffer alteration or buffer reduction is permitted by this chapter, a mitigation plan shall be required to describe the methods the applicant will use to minimize impacts to wetland functions. A detailed mitigation plan shall be approved by the city prior to any development activity occurring on a lot upon which wetland or wetland buffer alteration, restoration, creation or enhancement is proposed. See EMC 19.37.075 for required wetland mitigation plan content. (Ord. 3676-19 § 15, 2019; Ord. 3457-15 § 5, 2015; Ord. 2909-06 § 12, 2006.)