40.450.020    Rating Systems

A.    General.

1.    The wetland rating system is used in part to determine buffer widths pursuant to Section 40.450.030(E). The wetland rating and buffer systems are also used for mitigation and enhancement options under Section 40.450.040.

2.    The determination of the specific category of wetland and buffer for each wetland shall be the responsibility of the department.

B.    Wetland Rating System.

    Wetlands shall be rated according to the Washington State Department of Ecology wetland rating system found in the Washington State Wetland Rating System for Western Washington (Ecology Publication #04-06-025, August 2004). The rating system document contains the definitions and methods for determining if the criteria below are met:

1.    Wetland Rating Categories.

a.    Category I. Category I wetlands are:

(1)    Wetlands that are identified by scientists of the Washington Natural Heritage Program/DNR as high quality wetlands;

(2)    Bogs larger than one-half (1/2) acre;

(3)    Mature and old growth forested wetlands, as defined by WDFW priority habitat and species provisions, larger than one (1) acre; or

(4)    Wetlands that perform many functions well, as characterized by a wetland score of seventy (70) or greater on the rating form.

    Category I wetlands represent a unique or rare wetland type, are more sensitive to disturbance than most wetlands, are relatively undisturbed and contain some ecological attributes that are impossible to replace within a human lifetime, or provide a very high level of functions.

b.    Category II. Category II wetlands are:

(1)    A wetland identified by the Washington State Department of Natural Resources as containing “sensitive” plant species;

(2)    A bog between one-quarter (1/4) and one-half (1/2) acre in size; or

(3)    Wetlands with a moderately high level of functions, as characterized by a wetland score of fifty-one (51) through sixty-nine (69) on the rating form.

    Category II wetlands are difficult, though not impossible, to replace, and provide high levels of some functions. These wetlands occur more commonly than Category I wetlands, but they still need a relatively high level of protection.

c.    Category III. Category III wetlands are wetlands with a moderate level of functions, as characterized by a score of thirty (30) through fifty (50) on the rating form. Generally, wetlands in this category have been disturbed in some way and are often less diverse or more isolated from other natural resources in the landscape than Category II wetlands.

d.    Category IV. Category IV wetlands have the lowest levels of functions and are often heavily disturbed. They are characterized by a score of less than thirty (30) on the rating form. These are wetlands that should be replaceable, and in some cases may be improved. However, experience has shown that replacement cannot be guaranteed in any specific case. These wetlands may provide some important functions, and should be protected to some degree.

2.    Date of Wetland Rating. Wetland rating categories shall be applied as the wetland exists on the date of adoption of the rating system by the local government, as the wetland naturally changes thereafter, or as the wetland changes in accordance with permitted activities. Wetland rating categories shall not change due to illegal modifications.

(Amended: Ord. 2006-05-27)