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(1) Restoration is required when a wetland or its buffer has been altered in violation of this title. The following minimum performance standards shall be met for the restoration of a wetland, provided that if it can be demonstrated by the applicant that greater functional and habitat values can be obtained, these standards may be modified:

(a) The original wetland configuration should be replicated, including depth, width, and length at the original location.

(b) The original soil types and configuration shall be replicated.

(c) The wetland, including buffer areas, shall be replanted with native vegetation, which replicates the original species, sizes, and densities.

(d) The original functional values shall be restored, including water quality and wildlife habitat functions.

(e) Required replacement ratios are shown in the Reestablishment or Creation column of Table 28.16.120(3), Wetland Mitigation Ratios (for Eastern Washington).

(2) A restoration plan shall be prepared and approved prior to commencement of restoration work. Such a plan shall be prepared by a qualified wetland biologist and describe how the proposed actions meet the minimum requirements described above. The Department of Community and Economic Development shall, at the applicant’s expense, seek expert advice in determining the adequacy of the restoration plan. Inadequate plans shall be returned to the applicant for revision and resubmittal.

(3) Wetland mitigation ratios are provided in Table 28.16.120(3).

Table 28.16.120(3). Wetland Mitigation Ratios (for Eastern Washington)

Category and Type of Wetland Impacts

Reestablishment or Creation

Rehabilitation Only1

Reestablishment or Creation and Rehabilitation1

Reestablishment or Creation and Enhancement1

Enhancement Only1

All Category IV



1:1 R/C and 1:1 RH

1:1 R/C and 2:1 E


All Category III



1:1 R/C and 2:1 RH

1:1 R/C and 4:1 E


All other Category II



1:1 R/C and 4:1 RH

1:1 R/C and 8:1 E


Category I based on score for functions



1:1 R/C and 6:1 RH

1:1 R/C and 12:1 E


Category I Natural Heritage site

Not considered possible2

6:1 Rehabilitation of a Natural Heritage site

R/C not considered possible2

R/C not considered possible2



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.

2Natural heritage sites, alkali wetland, and bogs are considered irreplaceable wetlands because they perform some 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.

Reference: Washington State Department of Ecology, U.S. Army Corps of Engineers Seattle District, and U.S. Environmental Protection Agency Region 10, March 2006. Wetland Mitigation in Washington State – Part 1: Agency Policies and Guidance (Version 1). Washington State Department of Ecology Publication #06-06-011a. Olympia, Washington.

E = Enhancement

R/C = Re-establishment or Creation

RH = Rehabilitation

[Ord. 4525 § 1, 2021; Ord. 3911 § 2, 2009; Code 1970 § 28.16.120.]