30.62A.340 Standards and requirements for activities conducted in wetlands

30.62A.340 Standards and requirements for activities conducted in wetlands.

Protection of wetlands is inextricably linked to protection of the adjacent buffer areas. Standards and requirements for the buffers adjacent to wetlands are found in SCC 30.62A.320. Additional standards and requirements for development activities, actions requiring project permits and clearing within wetlands are in this section.

(1) Standards for wetlands - prohibitions. The following actions are prohibited:

(a) Filling of estuarine wetlands, wetlands listed by the Washington Natural Heritage Program as having High Conservation Value, mature forested wetlands and Category I bogs;

(b) Point discharges of stormwater into Category I bogs; and

(2) Standards for wetlands - no mitigation required. All development activities, actions requiring project permits and clearing that do not encroach into wetlands and provide buffers consistent with the requirements of SCC 30.62A.320(1)(a) through (f) and the prohibitions in subsection (1) of this section satisfy the avoidance criteria of SCC 30.62A.310(3) and do not require mitigation.

(3) Standards for wetlands - mitigation required. The actions, structures and facilities listed in this section are allowed only when they are determined to be unavoidable pursuant to SCC 30.62A.310, are consistent with the prohibitions in subsection (1) of this section, and are conducted according to the standards and requirements identified in this section. When a permit is required, an applicant must also provide a critical area study meeting the requirements of SCC 30.62A.140 and a mitigation plan meeting the requirements of SCC 30.62A.150.

(a) New utilities and transportation structures are allowed within wetlands provided no other feasible alternative exists.

(b) Stormwater detention/retention facilities are prohibited in Category I bogs pursuant to subsection (1)(b) of this section but are otherwise allowed pursuant to the requirements of SCC 30.63A.570.

(4) Standards for wetlands - mitigation requirements.

(a) Mitigation ratios – Except as provided in subsection (4)(b) of this section, to mitigate the loss of wetland functions, the ratios in Table 4 shall be required. The ratios are expressed in terms of the units of area needed to replace the lost functions and values of the wetland.

(b) For temporary impacts, the ratios shall be to be 1:1. Temporary impacts are those that can be restored to pre-disturbance conditions in one growing season.

Table 4 Wetland Mitigation Ratios
Category/Type of Wetland	Creation	Enhancement ¹
All Category IV	1.5:1	3:1

All Category III	2:1	4:1

Category II Estuarine	innovative development only	4:1
All other Category II	3:1	6:1

Category I based on score for functions	4:1	8:1
Category I listed by the Washington Natural Heritage Program as having High Conservation Value	Innovative development only	Innovative development only
Category I Coastal Lagoon	Innovative development only	Innovative development only
Category I Bog	Not allowed	Innovative design only
Category I Estuarine	Innovative development only	Innovative development only

1Enhancement is allowed in lieu of creation for up to one acre of wetland fill

(c) To reduce wetland buffer widths from the width required for high intensity land uses, optional mitigation measures and process requirements may be applied to reduce wetland buffer widths as shown in SCC 30.62A.320(1)(a) Table 2b.

(i) Optional mitigation measures.

(A) Mitigation measure 1. All applicable mitigation measures from Table 5 may be used to mitigate impacts to wetlands from high intensity land uses. When fencing and/or separate tracts are used pursuant to this section additional buffer width reductions for fencing or separate tracts otherwise allowed in SCC 30.62A.320(1) shall not be applied;

Table 5 Mitigation Measures for High Intensity Land Uses
Examples of disturbance	Activities and uses that cause disturbances	Examples of measures to minimize impacts
Lights	• Parking lots • Warehouses • Manufacturing • Residential	• Direct lights away from wetland
Noise	• Manufacturing • Residential	• Locate activity that generates noise away from the wetland
Toxic runoff *	• Parking lots • Roads • Manufacturing • Residential areas • Landscaping	• Route all new untreated runoff away from wetland while ensuring that wetland is not dewatered • Establish covenants governing use of pesticides within 150 feet of wetland • Apply integrated pest management
Stormwater runoff	• Parking lots • Roads • Manufacturing • Residential areas • Commercial • Landscaping	• Retrofit stormwater detention and treatment for roads and existing adjacent development • Prevent channelized flow from lawns that directly enters buffer
Change in water regime	• Impermeable surfaces • Lawns • Tilling	• Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surface and new lawns
Pets and human disturbance	• Residential areas	• Use privacy fencing; plant dense vegetation to delineate buffer edge and to discourage disturbance using vegetation appropriate for the ecoregion; place wetland and its buffer in a separate tract

*These examples are not necessarily adequate for minimizing toxic runoff if threatened or endangered species are present at the site.

(B) Mitigation measure 2. For Category I or II wetlands that score moderate or high for habitat (5 points or more for the habitat functions), a habitat corridor shall be preserved that meets the following criteria:

(I) Except as allowed in number (II) below, the habitat corridor shall connect the Category I or II wetland with a habitat score of 5 or more to any other wetland, fish and wildlife habitat conservation area or buffer which is:

(aa) on the same property or within the same development, including all phases proposed;

(bb) on adjacent properties and already protected as Native Growth Protection Areas or Critical Area Protection Areas or other permanently protected open space suitable for wildlife habitat use and which either extends to the property boundary or connected by easement; or

(cc) on county, state or federal land used for forestry, conservation or passive recreation parks.

(II) The habitat corridor may connect to a stormwater detention facility, either on-site or on an adjacent site, if it is designed to replicate a natural pond or wetland.

(III) The habitat corridor shall meet the following minimum physical characteristics:

(aa) The corridor shall consist of a relatively undisturbed, vegetated corridor.

(bb) The corridor shall maintain an average width equal to the difference between the high intensity buffer and the standard buffer for the relevant Category I or II wetland as shown in Table 6, except when the corridor is connecting two Category I or II wetlands each with a habitat score of 5 or more and the corridor maintains an average width of 100 feet, it will fulfill the connection requirement for both wetlands.

Table 6 Average Width for Habitat Corridor (Feet)
Wetland Category	Description	Standard Buffer Width	High Intensity Buffer Width	Average Habitat Corridor Width
Category I	Listed by the Washington Natural Heritage Program as having High Conservation Value	190	250	60
	Bogs	190	250	60
	Estuarine (at least 1 acre) & Coastal Lagoons	150	200	50
	High Level Habitat Function (habitat function score is 8 or greater)	225	300	75
	Moderate Level Habitat Function (habitat function score is 5-7)	110	150	40
Category II	Estuarine (less than 1 acre)	110	150	40
	High Level Habitat Function (habitat function score is 5-7)	225	300	75
	Moderate Level Habitat Function (habitat function score is 5-8)	110	150	40

(cc) The corridor shall maintain a width at each connection not less than the required average width as described in subsection (4)(c)(i)(B)(III)(bb) of this section.

(dd) The director may approve alternative configurations which meet the intent of no net loss of habitat functions and values pursuant to SCC 30.62A.350.

(IV) The following activities are allowed within the habitat corridor:

(aa) If the corridor maintains an average width of 100 feet or more, an unpaved trail - narrow single file walking path no bicycles or motorized vehicles allowed - may be allowed.

(bb) Vegetation management is allowed as follows:

(A) hazardous tree management - creation of snags and down logs is favored over tree removal whenever possible

(B) hand removal of invasive plant species

(C) when trails are allowed as per subsection (4)(c)(i)(B)(IV)(aa) of this section, minimal trail maintenance is also allowed

(D) restorative/enhancement plantings with native species to increase species diversity or replace plants lost to disease or damage; and

(E) planting with native species along outer edge of corridor to increase plant density and discourage disturbance or intrusion.

(ii) Process requirements in Part 100 shall be supplemented with the necessary information to document the mitigation locations and protection requirements, provide an assessment of functions and values and evaluation of the level of protection achieved by the mitigation measures and establish provisions for permanent protection. (Added by Amended Ord. 06-061, Aug. 1, 2007, Eff date Oct. 1, 2007; Amended by Amended Ord. 10-026, June 9, 2010, Eff date Sept. 30, 2010; Amended by Amended Ord. 15-034, Sept. 2, 2015, Eff date Nov. 1, 2015).