18E.30.020 Wetland Areas | Pierce County Code

18E.30.020 Wetland Areas.

1. Wetlands are those areas that are inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.

2. The County will require the use of the following documents to determine the presence or absence of potential wetlands:

a. The most recent edition of the federal wetland delineation manual and applicable regional supplements approved by the Washington State Department of Ecology.

B. Wetland Indicators. Indicators of wetlands normally include, but are not limited to: saturated soils or standing water; water-tolerant plant species such as salmonberry, Oregon ash, Western red cedar, rushes and sedges; and dark-brown or black soil colors. Refer to the documents listed in PCC 18E.30.020 A.2. for detailed wetland indicator criteria.

C. Potential Wetland Areas. Potential wetland areas, as depicted on the Critical Areas Atlas – County Wetland Inventory Maps, are those areas where wetland indicators have been mapped or identified. Potential wetlands include:

1. Areas within 315 feet of: hydric soils identified on the Soil Survey of Pierce County and Soil Survey of Snoqualmie Pass area; wetlands identified on the National Wetland Inventory Maps or Pierce County Wetland Inventory Maps; areas of known flooding identified on the FEMA FIRM and Flood Insurance Study Maps; or any other indicators of hydrology such as Department of Natural Resource stream data.

2. Areas that possess one or a number of wetland indicators as set forth in PCC 18E.30.020 B. and any adjacent areas within 315 feet.

3. Areas within the buffer of any wetland previously identified through the wetland review process.

D. Wetland Categories. Wetlands shall be classified into categories which are reflective of each wetland's function and value and unique characteristics. Wetland categories shall be based on the generalized criteria provided in PCC 18E.30.070 – Appendix A and the specific criteria provided in the Washington State Wetland Rating System for Western Washington (Ecology Publication #04-06-025). Wetlands shall be generally designated as follows:

1. Category I Wetlands. Category I wetlands are those regulated wetlands of exceptional resource value based on their functional value and diversity, wetland communities of infrequent occurrence, association with documented habitat for sensitive, threatened or endangered animal species, and other attributes which may not be adequately replicated through creation or restoration.

2. Category II Wetlands. Category II wetlands are those regulated wetlands of significant resource value based on their functional value and diversity, wetland communities of infrequent occurrence, and other attributes which may not be adequately replicated through creation or restoration.

3. Category III Wetlands. Category III wetlands are those regulated wetlands that have important resource value, principally due to vegetative diversity.

4. Category IV Wetlands. Category IV wetlands are those regulated wetlands of ordinary resource value based on monotypic vegetation of similar age and class, lack of special habitat features, and isolation from other aquatic systems.

1. Categorizing Wetlands Divided by a Manmade Feature. When a wetland is divided by a manmade feature (e.g., a road embankment), the wetland shall be rated as if it is not divided if there is a perennial or intermittent surface water connection between the two wetlands and any of the following criteria are met:

a. It can be demonstrated that the separate wetlands were one discrete wetland prior to construction of the manmade feature. This may be accomplished through an analysis of secondary information such as aerial photographs and soils maps; or

b. The two separated wetlands can be shown to function as one wetland. This shall be determined based on normal conditions (i.e., in the absence of unauthorized activity, the wetlands possess similar vegetative or wildlife assemblages or hydrologic regime).

c. Separated wetland areas may be rated jointly in the absence of a perfectly level culvert where it can be demonstrated that a level surface water connection is present within the culvert that permits flow of water, fish, or other organisms in both directions. Separated wetland areas may be rated jointly in the absence of a perfectly level culvert with two-way water flow if the bottom of the culvert is below the high water marks in the receiving wetland or if the high water marks on either side differ by six inches or less in elevation.

2. Connecting Mosaic Pattern Wetlands. In cases where the wetlands to be categorized are smaller than one acre in size and separated from each other by less than 100 feet (on average), the DOE mosaic methodology shall be used to determine the wetland category. The area of the wetlands must be greater than 50 percent of the total combined area of wetland and upland for the patchwork to be categorized as one wetland. The boundary of the mosaic wetlands must reflect the ecological interconnectedness of the wetlands within the mosaic. The County will not accept mosaic boundaries drawn to minimize the area of wetland within the mosaic. (See Figure 18E.30-1 in Chapter 18E.120 PCC.)