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In addition to the requirements in CMC 18.65.130 and 18.65.135, the following applies to mitigation to compensate for the adverse impacts associated with an alteration to a wetland:

(1) Mitigation measures must achieve equivalent or greater wetland functions, including, but not limited to:

(a) Habitat complexity, connectivity and other biological functions; and

(b) Seasonal hydrological dynamics, water storage capacity and water quality;

(2) The following ratios of area of mitigation to area of alteration apply to determine mitigation area required for permanent alterations:

Category

Creation or Re-establishment

Rehabilitation

Creation (C) and Rehabilitation (R) or Enhancement (E)

Enhancement Only

IV

1.5:1

3:1

1:1 C and 1:1 R or 2:1 E

6:1

III

2:1

4:1

1:1 C and 2:1 R or 4:1 E

8:1

II

3:1

6:1

1:1 C and 4:1 R or 8:1 E

12:1

I – forested

6:1

12:1

1:1 C and 10:1 R or 20:1 E

24:1

I – based on score for functions

4:1

8:1

1:1 C and 6:1 R or 12:1 E

16:1

I – bog

Not allowed

Case-by-case

Not possible

Case-by-case

(3) As an alternative to mitigation ratios provided in the table in subsection (2) of this section, the City of Covington may approve mitigation using the WDOE Calculating Credits and Debits for Compensatory Mitigation in Wetlands of Western Washington (Publication No. 10-06-011) (Hruby 2012) or as revised. This tool can be used to determine mitigation needs by estimating the functions and values lost when a wetland is altered, and estimating the gain in functions and values that result from the mitigation. This method must be applied by individuals trained and approved by Ecology in the use of this method;

(4) The City may consider two or more contiguous sites under common ownership as one site for the purpose of mitigation ratios when:

(a) All applicable sites are in the same drainage sub-basin;

(b) Equivalent or greater wetland functions will be achieved; and

(c) A notice on title, identifying the location, interconnectivity, and requirement for mitigation are recorded against each site pursuant to CMC 18.65.170;

(5) For temporary alterations to a wetland or its buffer that are predominantly woody vegetation, the City may require mitigation in addition to restoration of the altered wetland or buffer;

(6) For rectifying an illegal alteration to any category wetland or its buffer, the ratio of area of mitigation to area of alteration for repair, rehabilitation or restoration is one and one-half to one and the mitigation measures shall replicate the natural pre-alteration wetland configuration at its natural pre-alteration location to the maximum extent practical, including:

(a) The wetland edge and buffer configuration;

(b) The depth, width, length and gradient;

(c) The soil type, conditions and physical features;

(d) Similar species diversity and density; and

(e) The hydrologic, water quality, and biologic functions;

(7) Mitigation for an alteration to a buffer of a wetland that occurs along an aquatic area lake shoreline in accordance with an alteration identified in CMC 18.65.050 shall include, but not be limited to, on-site revegetation, maintenance and other restoration of the buffer or setback area to the maximum extent practical and shall be evaluated against the requirements of the City’s SMP (Chapter 16.05 CMC) if applicable; and

(8) The City may allow off-site mitigation for adverse impacts to buffers on the development proposal site at a ratio higher than that required for mitigation on site if the applicant demonstrates that it is not feasible to mitigate on the development proposal site, in the same wetland or wetland complex, pursuant to off-site mitigation requirements in CMC 18.65.135. (Ord. 09-19 § 9 (Exh. D); Ord. 06-17 § 4 (Exh. B))