19.70.245 Compensatory mitigation performance standards and requirements

19.70.245 Compensatory mitigation performance standards and requirements.

A. Compensatory Mitigation Plan. When a project involves wetland and/or buffer impacts, a compensatory mitigation plan must be included as part of the required critical area report. Compensatory wetland mitigation plans must meet the minimum requirements of AMC 19.70.125, Mitigation requirements, and demonstrate compliance with AMC 19.70.130, Mitigation plan requirements. Full guidance can be found in Wetland Mitigation in Washington State: Part 2 – Developing Mitigation Plans (Version 1) (Ecology Publication No. 06-06-011b, March 2006, or as revised). The mitigation plan must meet the following additional standards:

1. Description of the existing wetland and buffer areas proposed to be impacted. Include acreage (or square footage), water regime, vegetation, soils, landscape position, surrounding land uses, and functions. Also describe impacts in terms of acreage by Cowardin classification, hydrogeomorphic classification, and wetland rating, based on wetland ratings (AMC 19.70.215(B));

2. Description of the compensatory mitigation site, including location and rationale for selection. Include an assessment of existing conditions: acreage (or square footage) of wetlands and uplands, water regime, sources of water, vegetation, soils, landscape position, surrounding land uses, and functions. Estimate future conditions in this location if the compensation actions are not undertaken (i.e., how would this site progress through natural succession);

3. A description of the proposed actions for compensation of wetland and upland areas affected by the project. Include overall goals of the proposed mitigation, including a description of the targeted functions, hydrogeomorphic classification, categories of wetlands, and mitigation ratios applied (if ratio approach used);

4. A description of the proposed mitigation construction activities, construction/installation notes, and timing of activities;

5. A discussion of ongoing management practices that will protect wetlands after the project site has been developed, including proposed monitoring and maintenance programs (for remaining wetlands and compensatory mitigation wetlands);

6. Proof of establishment of notice on title for the wetlands and buffers on the project site, including the compensatory mitigation areas; and

7. The scaled plan sheets for the compensatory mitigation must contain, at a minimum:

a. An accurate depiction of the existing wetland and buffers, proposed areas of wetland and/or buffer impacts, location of proposed wetland and/or buffer compensation actions;

b. Existing topography, ground-proofed, at two-foot contour intervals in the zone of the proposed compensation actions if any grading activity is proposed to create the compensation area(s). Also existing cross-sections of on-site wetland areas that are proposed to be impacted and cross-section(s) (estimated one-foot intervals) for the proposed areas of wetland or buffer compensation;

c. Surface and subsurface hydrologic conditions, including an analysis of existing and proposed hydrologic regimes for enhanced, created, or restored compensatory mitigation areas. Also, illustrations of how data for existing hydrologic conditions were used to determine the estimates of future hydrologic conditions;

d. Conditions expected from the proposed actions on site, including future hydrogeomorphic types, vegetation community types by dominant species (wetland and upland), and future water regimes;

e. Required wetland buffers for existing wetlands and proposed compensation areas. Also, identify any zones where buffers are proposed to be reduced or enlarged outside of the standards identified in this chapter;

f. A plant schedule for the compensation area, including all species by proposed community type and water regime, size and type of plant material to be installed, spacing of plants, typical clustering patterns, typical plant installation details and notes, total number of each species by community type, timing of installation; and

g. Performance standards (measurable standards reflective of years post-installation) for upland and wetland communities, monitoring plan, contingency plan, and maintenance schedule, and actions. Standards for success must be established based on the performance standards identified and the functions and values being mitigated based on the guidance in Wetland Mitigation in Washington State: Part 2 – Developing Mitigation Plans (Version 1) (Ecology Publication No. 06-06-011b, March 2006, or as revised).

1. Compensatory mitigation for alterations to wetlands may be used only for impacts that cannot be avoided or minimized, except as otherwise exempted in AMC 19.70.230, Specific wetland category development standards, and must achieve equivalent or greater biologic functions. Compensatory mitigation plans must be consistent with Wetland Mitigation in Washington State: Part 2 – Developing Mitigation Plans (Version 1) (Ecology Publication No. 06-06-011b, March 2006, or as revised).

2. Mitigation ratios must be consistent with subsection (J) of this section.

3. Mitigation requirements may also be determined using the credit/debit tool described in “Calculating Credits and Debits for Compensatory Mitigation in Wetlands of Western Washington: Final Report, March 2012” (Ecology Publication No. 10-06-011, March 2012, or as revised) consistent with subsection (H) of this section.

C. Compensating for Lost or Impacted Wetland Functions. Compensatory mitigation must address the functions and values affected by the proposed project, with an intention to achieve functional equivalency or improvement of functions and values. The goal for the compensatory mitigation must be to provide similar wetland functions and values as those lost, except when either:

1. The lost wetland provides minimal functions and values, and the proposed compensatory mitigation action(s) will provide equal or greater functions and values or will provide functions and values shown to be limited within a watershed through a formal Washington State watershed assessment plan or protocol; or

2. Out-of-kind replacement of wetland type or functions and values will best meet watershed goals formally identified by the city, such as replacement of historically diminished wetland types.

D. Preference of Mitigation Actions. Methods to achieve compensation for wetland functions and values must be approached in the following order of preference:

1. Restoration. The manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural or historic functions to a former or degraded wetland. Restoration of wetlands includes reestablishment and rehabilitation.

a. Reestablishment. Returning natural or historic functions to a former wetland. Reestablishment results in a gain in wetland acres (and functions). Activities could include removing fill material, plugging ditches, or breaking drain tiles.

b. Rehabilitation. Repairing natural or historic functions of a degraded wetland. Rehabilitation results in a gain in wetland function but does not result in a gain in wetland acres. Activities could involve breaching a dike to reconnect wetlands to a floodplain or return tidal influence to a wetland.

2. Creation. Creation (establishment) of wetlands on disturbed upland sites, such as those with vegetative cover consisting primarily of nonnative species. This should be attempted only when there is an adequate source of water and it can be shown that the surface and subsurface hydrologic regime is conducive to the wetland community that is anticipated in the design.

3. Enhancement. Enhancement of significantly degraded wetlands in combination with restoration or creation. Enhancement alone will result in a loss of wetland acreage and is less effective at replacing the functions and values lost. Enhancement should be part of a mitigation package that includes replacing the impacted area and meeting appropriate ratio requirements.

4. Preservation. Preservation of high-quality, at-risk wetlands as compensation is generally acceptable when done in combination with restoration, creation, or enhancement; provided, that a minimum of one-to-one acreage replacement is provided by reestablishment or creation. Preservation of high-quality, at-risk wetlands and habitat may be considered as the sole means of compensation for wetland impacts when the following criteria are met:

a. Proposed wetland impacts will not have a significant adverse impact on habitat for listed fish, or other ESA-listed species;

b. There is no net loss of habitat functions within the watershed or basin;

c. Mitigation ratios for preservation as the sole means of mitigation must generally start at 20-to-one. Specific ratios should depend upon the significance of the preservation project and the quality of the wetland resources lost;

d. The impact area is small (generally less than one-half acre) and/or impacts are occurring to a low-functioning system (Category III or IV wetland); and

e. All preservation sites must include buffer areas adequate to protect the habitat and its functions from encroachment and degradation.

5. Wetland Bank or Advanced Wetland Mitigation. For future use since no current banks have a service area in Anacortes.

E. Type and Location of Compensatory Mitigation. Unless it is demonstrated that a higher level of ecological functioning would result from an alternative mitigation approach, compensatory mitigation for ecological functions should be either in-kind and on site, or in-kind and within the same stream reach, sub-basin, or drift cell (if estuarine wetlands are impacted). Compensatory mitigation actions must be conducted within the same sub-basin or on the site of the alteration, except when the following apply:

1. The conditions in subsection (B) of this section are met.

2. There are no reasonable opportunities on site or within the sub-basin (e.g., on-site options would require elimination of high-functioning upland habitat), or opportunities on site or within the sub-basin do not have a high likelihood of success based on a determination of the capacity of the site to compensate for the impacts. Considerations should include:

a. Anticipated replacement ratios for wetland mitigation;

b. Buffer conditions and proposed widths;

c. Available water to maintain anticipated hydrogeomorphic classes of wetlands when restored;

d. Proposed flood storage capacity, and potential to mitigate riparian fish and wildlife impacts (such as connectivity);

e. Off-site mitigation has a greater likelihood of providing equal or improved wetland functions than the impacted wetland;

f. Off-site locations must be in the same sub-basin, unless watershed goals for water quality, flood storage or conveyance, habitat, or other wetland functions have been established by the city and strongly justify location of mitigation at another site; and

g. The design for the compensatory mitigation project needs to be appropriate for its location (i.e., position in the landscape). Therefore, compensatory mitigation should not result in the creation, restoration, or enhancement of an atypical wetland. An atypical wetland refers to a compensation wetland (e.g., created or enhanced) that does not match the type of existing wetland that would be found in the geomorphic setting of the site (i.e., the water source(s) and hydroperiod proposed for the mitigation site are not typical for the geomorphic setting). Likewise, it should not provide exaggerated morphology or require a berm or other engineered structures to hold back water. For example, excavating a permanently inundated pond in an existing, seasonally saturated or inundated wetland is one example of an enhancement project that could result in an atypical wetland. Another example would be excavating depressions in an existing wetland on a slope, which would require the construction of berms to hold the water.

F. Wetland Mitigation Banks. Credits from a wetland mitigation bank certified under Chapter 173-700 WAC may be used to compensate for impacts located within the service area specified in the mitigation bank instrument, if:

1. The proposal would provide appropriate compensation for the proposed impacts;

2. The impact site is located in the service area of the bank;

3. The proposed use of credits is consistent with the terms and conditions of the certified mitigation bank instrument; and

4. Replacement ratios using bank credits are consistent with replacement ratios specified in the certified mitigation bank instrument.

G. In-Lieu Fee Mitigation. Credits from an approved in-lieu fee (ILF) program may be used when all of the following apply:

1. The decision-maker determines that it would provide environmentally appropriate compensation for the proposed impacts.

2. The proposed use of credits is consistent with the terms and conditions of the approved ILF program instrument.

3. Projects using ILF credits must have debits associated with the proposed impacts calculated by the applicant’s qualified wetland professional using the credit assessment method specified in the approved instrument for the ILF program.

4. The impacts are located within the service area specified in the approved ILF instrument.

H. Permittee-Responsible Mitigation. This type of mitigation is defined in 33 CFR 332 as “an aquatic resource restoration, establishment, enhancement and/or preservation activity undertaken by the permittee (or an authorized agent or contractor) to provide compensatory mitigation for which the permittee retains full responsibility.” The permittee performs the mitigation either before the project impact occurs and before any project impact permit is issued (advance permittee-responsible mitigation) or at the same time as the project impact is occurring after the project impact permit is issued (concurrent permittee-responsible mitigation). The permittee is ultimately responsible for implementation and success of the mitigation. For advance mitigation, the permittee generates mitigation credits that may be used to compensate for future wetland or buffer impacts. Only the permittee may use the advance mitigation credits. Permittee-responsible mitigation may occur at the site of the permitted impacts or at an off-site location within the same watershed. Permittee-responsible mitigation must be used only if the applicant’s qualified wetland professional demonstrates to the decision-maker’s satisfaction that the proposed approach is ecologically preferable to use of a bank or ILF program, consistent with the criteria in this section.

I. Alternative Mitigation Plan. The decision-maker may approve an alternative wetland mitigation plan that is based on best available science. Proposed alternative mitigation plans must provide an equivalent or better level of protection of wetland functions and values than would be provided by the strict application of this chapter.

1. The following will be considered in the approval of an alternative mitigation plan:

a. The plan uses a watershed approach consistent with “Selecting Wetland Mitigation Sites Using a Watershed Approach (Western Washington)” (Ecology Publication No. 09-06-032, Olympia, WA, December 2009).

b. Creation or enhancement of a larger system of natural areas and open space is preferable to the preservation of many individual small habitat areas.

c. Mitigation according to subsection (D) of this section is not feasible due to site constraints including but not limited to parcel size, stream type, wetland category, or geologically hazardous areas.

d. There is a clear potential for success of the proposed compensation at the identified site.

e. The plan must contain clear and measurable standards for achieving compliance with the specific provisions of the plan, consistent with AMC 19.70.130, Mitigation plan requirements.

f. The plan must be reviewed and approved as part of the overall approval of the proposed use.

g. A wetland of a different type may be justified based on regional needs or functions and values; the replacement ratios may not be reduced or eliminated unless the reduction results in a preferred environmental alternative.

h. Mitigation guarantees must meet the minimum requirements as outlined in AMC 19.70.150, Financial guarantee requirements.

i. Qualified professionals in each of the critical areas addressed must prepare the plan.

j. The city may consult with agencies with expertise and jurisdiction over the critical areas during the review to assist with analysis and identification of appropriate performance measures that adequately safeguard critical areas.

J. Wetland Mitigation Ratios. The ratios below 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.

Table 19.70.245 Wetland Mitigation Ratios
Category and Type of Wetland	Creation or Reestablishment	Rehabilitation Only	Reestablishment or Creation (R/C) and Rehab (RH)	Reestablishment or Creation (R/C) and Enhancement (E)	Enhancement Only
Category I Mature Forested	6:1	12:1	1:1 R/C & 10:1 RH	1:1 R/C & 20:1 E	24:1
Category I – based on score for functions	4:1	8:1	1:1 R/C & 6:1 RH	1:1 R/C & 12:1 E	16:1
Category I Natural Heritage Site	Not allowed	6:1 Rehabilitation of a Natural Heritage Site	Not allowed	Not allowed	Case-by-case
Category I Bog	Not allowed	6:1 Rehabilitation of a bog	Not allowed	Not allowed	Case-by-case
Category I Estuarine	Case-by-case	6:1 Rehabilitation of an estuarine wetland	Case-by-case	Case-by-case	Case-by-case
Category II	3:1	6:1	1:1 R/C & 4:1 RH	1:1 R/C & 8:1 E	12:1
Category III	2:1	4:1	1:1 R/C & 2:1 RH	1:1 R/C & 4:1 E	8:1
Category IV	1.5:1	3:1	1:1 R/C & 1:1 RH	1:1 R/C & 2:1 E	6:1

K. Buffer Mitigation Ratios. Impacts to buffers must be mitigated at a one-to-one ratio. Compensatory buffer mitigation must replace those buffer functions lost from development.

L. Mitigation Performance Standards. Wetland mitigation plans must be consistent with AMC 19.70.125, Mitigation requirements, and AMC 19.70.130, Mitigation plan requirements, and “Wetland Mitigation in Washington State: Part 1 – Agency Policies and Guidance” (Version 1, Ecology Publication No. 06-06-011a), or as amended, and best available science.

M. Minimum Standards. The design standards in this section must be incorporated into mitigation plans submitted to the city for impacts to wetlands and/or wetland buffers. The following standards apply to any mitigation proposed within Category I, II, III and IV wetlands and their buffers. Modifications to these design standards consistent with the guidance in “Wetland Mitigation in Washington State: Part 2 – Developing Mitigation Plans (Version 1)” (Ecology Publication No. 06-06-011b, March 2006, or as revised) may be considered for approval by the decision-maker as alternatives to the following standards:

1. Plants native to the region (not introduced, nonnative or exotic species) must be used.

2. Plant species selection must be consistent with the existing or projected hydrologic regime, including base water levels and stormwater event fluctuations.

3. Plant species selection must be consistent with the site environmental conditions such as slope, aspect, soils and exposure to sun, wind and rain.

4. Plants should be commercially available or available from local sources.

5. Native plant species high in food and cover value for fish and wildlife should be prioritized, as appropriate for the site.

6. Plant selection must be approved by a qualified professional.

7. The following standards apply to wetland design and construction:

a. For wetland creation sites, preliminary investigations of existing hydrology at the site must be completed to confirm that the site has adequate source hydrology (e.g., high groundwater, precipitation or riverine flooding) to support wetland conditions.

b. Water depth in areas of seasonal or occasional inundation must not exceed three feet (0.914 meters), unless the proposed mitigation is compensating for impacts to unvegetated/open water areas.

c. If creating or rehabilitating a slope wetland, the grade or slope within the wetland must not exceed six percent, unless otherwise approved by the decision-maker.

d. Slopes within the wetland contributing basin and the buffer zone must not be steeper than three-to-one (horizontal to vertical).

e. The wetland (excluding the buffer area) should not contain more than 20 percent unvegetated/open water areas as measured at the seasonal high water mark, unless the mitigation is compensating for vegetated.

f. Site soils must be free of contamination and/or hazardous materials, and must have adequate organic content and porosity to support the proposed native plant community.

g. Planting densities and placement of plants should be determined by a qualified professional and shown on the design plans.

8. The planting plan must be approved by the city.

9. Stockpiling soil and construction materials should be confined to upland areas and contract specifications should limit stockpiling of earthen materials to durations in accordance with city clearing and grading standards, unless otherwise approved by the city.

10. Planting instructions must be submitted which describe placement, diversity, and spacing of seeds, tubers, bulbs, rhizomes, sprigs, plugs, and transplanted stock.

11. Controlled release fertilizer (if required) must be used in upland areas only (buffers and other nonwetland areas) and must be installed into the planting hole only at the time of planting. No fertilizer must be applied to the ground surface.

12. An irrigation system must be installed or watering afforded by trucks or hoses to provide water for installed plants and seeded areas to supplement rainfall to ensure that plants receive approximately one-half inch of water per week during the dry season of the first two years after plant installation.

13. All construction specifications and methods must be approved by a qualified professional and the city.

14. Construction management provided must be provided by a qualified professional. Ongoing work on site must be inspected by the city. (Ord. 4025 § 2 (Att. A), 2022; Ord. 3064 § 2 (Att. A), 2021)