The purposes of this article are to:
A. 
Recognize and protect the beneficial functions, values, and services performed by wetlands, which include, but are not limited to, providing food, breeding, nesting and/or rearing habitat for fish and wildlife; recharging and discharging groundwater; contributing to stream flow during low flow periods; stabilizing stream banks and shorelines; storing storm and flood waters to reduce flooding and erosion; and improving water quality through biofiltration, adsorption, retention and transformation of sediments, nutrients, and toxicants.
B. 
Regulate land use to avoid adverse effects on wetlands and maintain the functions, services, and values of freshwater and estuarine wetlands throughout Whatcom County.
C. 
Establish review procedures for development proposals in and adjacent to wetlands.
D. 
Establish minimum standards for identifying and delineating wetlands.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
A. 
Wetlands shall be delineated in accordance with the requirements of RCW 36.70A.175. Unless otherwise provided for in this chapter, all areas within the county determined to be wetlands in accordance with the U.S. Army Corps of Engineers Wetlands Delineation Manual, 1987 Edition, and the Western Mountains, Valleys, and Coast Region Supplement (Version 2.0), 2010, or as revised, are hereby designated critical areas and are subject to the provisions of this article.
B. 
The approximate location and extent of wetlands are shown on the county's critical area maps. A property-specific assessment is necessary to determine the wetland boundary.
C. 
Wetlands shall be rated based on categories that reflect the functions and values of each wetland. Wetland categories shall be based on the criteria provided in the Washington State Wetland Rating System for Western Washington, revised 2014, and as amended thereafter, as determined using the appropriate rating forms and associated figures contained in that publication. These categories are generally defined as follows:
1. 
Category I. Category I wetlands are: (a) relatively undisturbed estuarine wetlands larger than one acre; (b) wetlands of high conservation value that are identified by scientists of the Washington Natural Heritage Program/DNR; (c) bogs; (d) mature and old-growth forested wetlands larger than one acre; (e) wetlands in coastal lagoons; (f) interdunal wetlands that score eight or nine habitat points and are larger than one acre; and (g) wetlands that perform many functions well (scoring 23 points or more). These wetlands: (a) represent unique or rare wetland types; (b) are more sensitive to disturbance than most wetlands; (c) are relatively undisturbed and contain ecological attributes that are impossible to replace within a human lifetime; or (d) provide a high level of functions.
2. 
Category II. Category II wetlands are: (a) estuarine wetlands smaller than one acre, or disturbed estuarine wetlands larger than one acre; (b) interdunal wetlands larger than one acre or those found in a mosaic of wetlands; or (c) wetlands with a moderately high level of functions (scoring between 20 and 22 points).
3. 
Category III. Category III wetlands are: (a) wetlands with a moderate level of functions (scoring between 16 and 19 points); (b) can often be adequately replaced with a well-planned mitigation project; and (c) interdunal wetlands between 0.1 and one acre. Wetlands scoring between 16 and 19 points generally have been disturbed in some ways and are often less diverse or more isolated from other natural resources in the landscape than Category II wetlands.
4. 
Category IV. Category IV wetlands have the lowest levels of functions (scoring fewer than 16 points) and are often heavily disturbed. These are wetlands that we should be able to replace, or in some cases to improve. 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.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
A. 
All wetlands shall be regulated regardless of size; provided, that the following wetlands may be exempt from the requirement to avoid impacts (WCC § 16.16.225, General regulations), and they may be filled if the impacts are fully mitigated based on the remaining actions in WCC § 16.16.260 (General mitigation requirements). In order to verify the following conditions, a critical area report for wetlands meeting the requirements in WCC § 16.16.255 (Critical areas assessment reports) must be submitted:
1. 
All isolated Category IV wetlands less than 4,000 square feet that:
a. 
Are not associated with riparian areas or their buffers;
b. 
Are not associated with shorelines of the state or their associated buffers;
c. 
Are not part of a wetland mosaic;
d. 
Do not score six or more points for habitat function based on the 2014 update to the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by Ecology);
e. 
Do not contain a priority habitat or a priority area for a priority species identified by the Washington Department of Fish and Wildlife, do not contain federally listed species or their critical habitat, or species of local importance identified in WCC § 16.16.710 (Habitat conservation areas – Designation, mapping, and classification).
2. 
Wetlands less than 1,000 square feet that meet the above criteria and do not contain federally listed species or their critical habitat are exempt from the buffer provisions contained in this chapter.
(Ord. 2024-047 § 2 (Exh. F))
The following uses and modifications may be permitted in wetlands and/or wetland buffers as specified when, pursuant to WCC § 16.16.255, § 16.16.260, and § 16.16.630, all reasonable measures have been taken to avoid adverse effects on wetland functions and values as documented through an alternatives analysis, the amount and degree of alteration are limited to the minimum needed to accomplish the project purpose, and mitigation is provided for all adverse impacts to wetlands and their buffers that cannot be avoided:
A. 
Reasonable Use. Developments that meet the reasonable use exception standards as set forth in WCC § 16.16.270.
B. 
Utilities.
1. 
Utility lines in Category II, III, and IV wetlands and their buffers and/or Category I wetland buffers when no feasible conveyance alternative is available shall be designed and constructed to minimize physical, hydrologic, and ecological impacts to the wetland, and meet all of the following:
a. 
The utility line is located as far from the wetland edge and/or buffer as possible and in a manner that minimizes disturbance of soils and vegetation.
b. 
Clearing, grading, and excavation activities are limited to the minimum necessary to install the utility line and the area is restored following utility installation.
c. 
Buried utility lines shall be constructed in a manner that prevents adverse impacts to surface and subsurface drainage. This may include regrading to the approximate original contour or the use of trench plugs or other devices as needed to maintain hydrology.
d. 
Best management practices are used in maintaining said utility corridors such that maintenance activities do not expand the corridor further into the critical area.
e. 
The least impactful construction or installation method is used as demonstrated through an alternatives analysis.
2. 
On-site sewage disposal systems (OSS) may be permitted in wetland buffers when accessory to an approved single-family residence when:
a. 
It is not feasible to connect to a public sanitary sewer system; and
b. 
It is located as far as possible from the wetland; and
c. 
It is operated and maintained in accordance with WCC § 24.05.280; provided, that adverse effects on water quality are avoided.
C. 
Public Roads or Bridges. New or expanded public roads or bridges in Category II, III, and IV wetlands and their buffers and/or Category I wetland buffers when no feasible alternative alignment is available and the road or bridge is designed and constructed to minimize physical, hydrologic, and ecological impacts to the wetland, including placement on elevated structures as an alternative to fill, where feasible.
D. 
Private Access. Access to private development sites may be permitted to cross Category II, III, or IV wetlands or their buffers, provided the access meets the following:
1. 
For direct wetland fill, there are no feasible alternative alignments. Alternative access shall be pursued to the maximum extent feasible, including through the provisions of Chapter 8.24 RCW.
2. 
Design and construction methods maintain preconstruction hydrologic connectivity across the access road or driveway.
3. 
The access is designed to cause the least impact to the wetland and/or its buffer (which may require the applicant to apply for an exception or deviation from the development standards).
4. 
Access is not achievable through the administrative provisions of WCC § 16.16.640 (Wetland buffer modification).
E. 
Agricultural Uses.
1. 
Construction of an appurtenant structure that is associated with an agricultural use; or the reconstruction, remodeling, or maintenance of such structures in wetland buffers, subject to all of the following specific criteria:
a. 
The structure is located within an existing lot of record and is an ongoing agricultural use.
b. 
There is no other feasible location with less impact to critical areas.
c. 
Clearing and grading activity and impervious surfaces are limited to the minimum necessary to accommodate the proposed structure and, where possible, surfaces shall be made of pervious materials.
2. 
Ongoing agricultural activities, subject to the following:
a. 
The activities are conducted in accordance with all applicable provisions of this chapter and WCC Title 17; or
b. 
The agricultural activity is in compliance with the Conservation Program on Agricultural Lands (CPAL) as described in Article 8 of this chapter.
F. 
Domestic wells serving single-family developments (including plats, short plats, and individual single-family residences) and necessary appurtenances, including a pump and appropriately sized pump house, but not including a storage tank, in wetland buffers when all of the following conditions are met:
1. 
There is no viable alternative to the well site outside of the buffer and the well is located as far back from the wetland edge as is feasible;
2. 
The well is more than 75 feet deep; and
3. 
Any impacts to the wetland and buffer from staging equipment and the well-drilling process are mitigated.
G. 
Stormwater Management Facilities.
1. 
Stormwater management facilities, limited to detention/retention/treatment ponds, media filtration facilities, and lagoons or infiltration basins, or bioretention cells (engineered or rain gardens) may be permitted within the outer 50 percent of a Category II, III or IV wetland buffer; provided, that:
a. 
Construction of the stormwater facility does not displace or impact a forested buffer;
b. 
The width of the buffer between the stormwater facility and the wetland edge is not less than the low intensity land use buffer standards in WCC § 16.16.630;
c. 
There is no other feasible location for the stormwater facility and the facility is located, constructed, and maintained in a manner that minimizes adverse effects on the buffer and adjacent critical areas;
d. 
The stormwater facility is designed to mimic and resemble natural wetlands and meets applicable county or state stormwater management standards and the discharge water meets state water quality standards; and
e. 
Low impact development approaches have been implemented to the maximum extent feasible per the Department of Ecology stormwater manual.
2. 
Surface water or stormwater conveyance or discharge facilities such as dispersion trenches, level spreaders, and outfalls may be permitted within a Category III or IV wetland buffer on a case-by-case basis when the director determines that all of the following are met:
a. 
Due to topographic or other physical constraints, there are no feasible alternative locations for these facilities in the outer buffer area or outside the buffer.
b. 
The discharge is located as far from the wetland edge and/or buffer as possible and in a manner that minimizes disturbance of soils and vegetation.
c. 
The discharge outlet is designed to prevent erosion and promote infiltration.
d. 
The dispersion outfall is within the outer 25 percent of the buffer, unless a closer location is demonstrated to be the only feasible location. Alternative locations shall be the maximum distance from the wetland to alleviate the site constraint.
3. 
Phosphorus-reducing BMP structures approved and installed through the homeowners' improvement program (or as may be renamed) within the Lake Whatcom watershed to treat runoff from existing development may be permitted within the outer 50 percent of a Category II, III or IV wetland buffer.
H. 
Recreation. Passive recreation facilities that are part of a nonmotorized trail system or environmental education program, including walkways, wildlife viewing structures, or public education trails; provided, that all of the following criteria are met:
1. 
There is no other feasible alternative route with less impact on the critical area.
2. 
The trail minimizes erosion and sedimentation, hydrologic alteration, and disruption of natural processes such as wood recruitment and natural wildlife movement patterns.
3. 
Private trails shall not exceed four feet in width and public trails shall not exceed 10 feet in width, though some portions may be wider to meet the requirements of the Americans with Disabilities Act.
4. 
They shall be made of pervious material or elevated where feasible.
5. 
They shall be designed to avoid removal of significant trees.
6. 
Trails may include limited viewing platforms that shall not exceed eight feet in width and shall be made of pervious materials where feasible.
7. 
When located in the buffer, they should be located in the outer 25 percent of the buffer; except, that public trails may be permitted closer to the wetland when necessary to provide wetland educational opportunities or for public health and safety; provided, that when closer than the outer 25 percent, the trail width is the minimum necessary for the trail class.
8. 
They shall be constructed and maintained in a manner that minimizes disturbance of the buffer and associated critical areas.
9. 
If they must cross a wetland, they shall be elevated, constructed to minimize supports, and be the minimum size necessary to accommodate the level of service.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
To protect the integrity, functions, and values of wetlands, the director shall have the authority to require buffers from the edges of all wetlands, including reestablished or created wetlands, (in addition to the building setback required by WCC § 16.16.265(A)(1)) in accordance with the following:
A. 
Wetland buffers shall be measured horizontally from a perpendicular line established by the wetland boundary based on the base buffer width identified in Table 1.
B. 
Wetland buffers shall not include areas that are functionally and effectively disconnected from the wetland by an existing, legally established road or other substantially developed surface.
C. 
The wetland buffer standards required by this article presume the existence of a dense, multi-storied native vegetation community in the buffer adequate to protect the wetland functions and values. When a buffer lacks adequate vegetation, the director may increase the standard buffer, require buffer planting or enhancement, and/or deny a proposal for buffer reduction or buffer averaging.
D. 
The standard wetland buffer shall be based on a combination wetland category, habitat function score (from the wetland rating form), and land use intensity. The intensity of the land use shall be determined in accordance with the definitions found in Article 9 of this chapter unless the director determines that a lesser level of impact is appropriate based on information provided by the applicant demonstrating that the proposed land use will have a lesser impact on the wetland than that contemplated under the buffer standard otherwise appropriate for the land use, as specified in WCC § 16.16.640.
E. 
Standard buffer widths are shown in Table 1. However, for Category I or II wetlands with "special characteristics" as determined and defined through the Washington State Department of Ecology (2014) Wetland Rating System (including estuarine, coastal lagoons, wetlands of high conservation value, bogs, forested, and interdunal wetlands), only buffers in the highest habitat score (8 to 9) group are applied.
Table 1. Standard Wetland Buffer Widths
Wetland Category
Habitat Function Score
Land Use Intensity*
High Buffer Width (feet)
Moderate Buffer Width (feet)
Low Buffer Width (feet)
Category I
8 – 9
6 – 7
3 – 5
300
150
100
225
110
75
150
75
50
Category II
8 – 9
6 – 7
3 – 5
300
150
100
225
110
75
100
75
50
Category III
8 – 9
6 – 7
3 – 5
300
150
100
225
110
60
150
75
40
Category IV
3 – 9
50
40
25
Notes:
* Definitions for high, moderate, and low intensity land use are provided in Article 9 of this chapter.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
Buffer widths may be increased, decreased, or averaged in accordance with the following provisions, which provide flexible approaches to maximize both ecological functions and allowed uses. All mitigation proposed shall be consistent with state regulations and this chapter.
A. 
Buffer Width Increasing. The director may require the standard buffer width to be increased by the distance necessary to protect wetland functions and provide connectivity to other wetland and habitat areas for one of the following:
1. 
To protect the function and value of that wetland including, but not limited to, compensating for a poorly vegetated buffer or a buffer that has a steep slope (greater than 30 percent); or
2. 
To prevent windthrow damage; or
3. 
To protect wetlands or other critical areas from landslides, erosion or other hazards; or
4. 
To maintain viable populations of existing species listed by the federal or state government as endangered, threatened or sensitive; or
5. 
When a Category I or II wetland is located within 300 feet of:
a. 
Another Category I, II or III wetland; or
b. 
A Fish and Wildlife HCA; or
c. 
A Type S or F stream; or
d. 
A high impact land use that is likely to have additional impacts.
The increased buffer distance may be limited to those areas that provide connectivity or are necessary to protect wetland and habitat functions. If the wetland contains variations in sensitivity, increasing the buffer widths will only be done where necessary to preserve the structure, function and value of the wetland.
B. 
Buffer Width Averaging. Buffer width averaging allows limited reductions of buffer width in specified locations while requiring increases in others. The widths of buffers may be averaged if this will improve the protection of wetland functions.
1. 
Averaging of required buffer widths will be allowed only if the applicant demonstrates that all of the following criteria are met:
a. 
The area of the buffer proposed for averaging has not been reduced pursuant to subsection C of this section. Buffer averaging is not allowed if the buffer has been reduced; and
b. 
Averaging is necessary to accomplish the purpose of the proposal and no reasonable alternative is available; and
c. 
Averaging width will not adversely impact the wetland functions and values; and
d. 
The wetland has significant differences in characteristics that affect its habitat functions; and
e. 
The total area contained within the wetland buffer after averaging is no less than that contained within the standard buffer prior to averaging; and
f. 
The buffer is increased adjacent to the higher-functioning area of habitat or more sensitive portion of the wetland and decreased adjacent to the lower functioning or less sensitive portion; and
g. 
The buffer width of a Category I, II, or III wetland shall not be reduced below 75 percent of the standard buffer width.
2. 
Averaging of required buffer widths will be allowed for the following when the dimensional standards of subsection (B)(1) of this section are met:
a. 
To protect a natural feature (e.g., a stand of trees or snags) that otherwise would fall outside of the standard buffer.
b. 
To provide connections with adjacent habitats or to address those situations where preexisting development has reduced a buffer area to a width less than the required standard.
C. 
Buffer Width Reduction. The director shall have the authority to reduce the standard buffer widths identified in WCC § 16.16.630 (Wetland buffers) as follows:
1. 
The buffers of moderate and low impact land use projects may be reduced when all of the following apply:
a. 
The area of the buffer proposed for reduction has not been averaged pursuant to subsection B of this section. Buffer reduction is not allowed if the buffer has been averaged.
b. 
The applicant demonstrates buffer averaging is not feasible.
c. 
The buffer shall not be reduced to less than 75 percent of the required buffer.
d. 
Prior to considering buffer reductions, the applicant shall demonstrate application of mitigation sequencing as required in WCC § 16.16.260 (General mitigation requirements).
e. 
To minimize impacts and provide equivalent functions and values as required by this section, the director may require any or all of the following:
i. 
The use of alternative on-site wastewater systems in order to minimize site clearing, where appropriate;
ii. 
Using low impact development (LID) and LID best management practices where appropriate;
f. 
The buffer reduction shall not adversely affect the functions and values of the adjacent wetlands;
g. 
All buffer reduction impacts are mitigated and result in equal or greater protection of the wetland functions and values. This includes enhancement of existing degraded buffer area and providing mitigation for the disturbed buffer area.
2. 
High impact land use projects may apply moderate land use intensity buffers when:
a. 
For wetlands that score three to five habitat points, all applicable impact reduction measures from the following list are implemented (from Department of Ecology Publication No. 05-06-008, Wetlands in Washington State, Volume 2, Appendix 8C (as updated in 2018)):
i. 
Directing lights away from the wetland and buffer.
ii. 
Locating activities that generate noise away from the wetland and buffer.
iii. 
Routing all new, untreated runoff away from wetland while ensuring wetland is not dewatered.
iv. 
Establishing covenants limiting use of pesticides within 150 feet of wetland.
v. 
Applying integrated pest management.
vi. 
Retrofitting stormwater detention and treatment for roads and existing adjacent development.
vii. 
Preventing channelized flow from lawns that directly enters the buffer.
viii. 
Infiltrating or treating, detaining, and dispersing into the buffer new runoff from impervious surfaces and new lawns.
ix. 
Posting signs at the outer edge of the critical area or buffer to clearly indicate the location of the critical area according to the direction of the county.
x. 
Using privacy fencing.
xi. 
Planting with dense native vegetation appropriate for the county to delineate buffer edge and to discourage disturbance.
xii. 
Using low impact development (LID) and LID best management practices where appropriate.
xiii. 
Establishing a permanent conservation easement or tract to protect the wetland and the associated buffer.
xiv. 
Using best management practices to control dust.
b. 
For wetlands that score six points or more for habitat function:
i. 
All applicable impact reduction measures of subsection (C)(2)(a) of this section are implemented; and
ii. 
A relatively undisturbed, vegetated corridor at least 100 feet wide between the wetland and any other priority habitats is protected pursuant to WCC § 16.16.260(J) (General Mitigation Requirements – Permanent Protection). If no option for providing such a corridor is available, then only subsection (C)(2)(b)(i) of this section applies.
3. 
In all circumstances when the buffer between the area of reduction and the wetland is degraded, this degraded portion of the buffer shall include replanting with native vegetation in order to achieve a dense vegetative community.
4. 
Any person who alters or proposes to alter regulated wetlands shall reestablish, create, rehabilitate, or enhance (or a combination thereof) areas of wetland in order to compensate for wetland losses at the ratios described in mitigation ratios for projects in Western Washington in Table 8C-11 (as updated in 2014) in Department of Ecology Publication No. 05-06-008, Wetlands in Washington State, Volume 2, Section 8C.2.3.
D. 
Buffer Width Variance. Standard buffer widths may be reduced by more than 25 percent through a variance pursuant to WCC § 16.16.273 (Variances); provided, that buffer averaging beyond that allowed in subsection B of this section is prohibited.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
A. 
When county critical area maps or other sources of credible information indicate that a site proposed for development or alteration may contain wetland indicators, contain or abut wetlands or wetland buffers, the director may require a site evaluation (reconnaissance) or critical area assessment report by a qualified professional to determine whether or not a regulated wetland is present and, if so, its relative location in relation to the proposed project area or site. If no regulated wetlands are present, then wetland review will be considered complete.
B. 
If the director determines that a wetland indicator is more likely than not present, s/he shall require a wetland assessment report pursuant to WCC § 16.16.255 and subsections C and D of this section.
C. 
A wetland assessment is an element of a critical area assessment report that describes the characteristics of the subject property and adjacent areas. The wetland assessment shall include the occurrence, distribution, delineation, and determination of the wetland category and standard wet-land buffers as set forth in WCC § 16.16.630, and may include analysis of historical aerial photos, and review of public records.
D. 
A wetland assessment shall include the following site- and proposal-related information unless the director determines that any portion of these requirements is already required by Article 2, or unnecessary given the scope and/or scale of the proposed development:
1. 
Location information (legal description, parcel number, and address);
2. 
A vicinity map;
3. 
A site plan that includes scale and wetlands and associated buffers and proposed development if appropriate;
4. 
A qualitative written assessment and accompanying maps of wetlands and buffers within 300 feet of the site and an estimate of the existing acreage for each. For on-site wetlands, the assessment shall include the dominant and subdominant plant species; soil type, color and texture; sources of hydrology (patterns of surface and subsurface water movement, precipitation, etc.); topography; and other pertinent information. The assessment of off-site wetlands shall be based on available information and shall not require accessing off-site properties;
5. 
Wetland Analysis. An analysis of all wetlands and buffers (to the extent they can be legally accessed) including, at a minimum, the following information:
a. 
Wetland delineation conducted by a qualified professional and completed in accordance with WCC § 16.16.610(A).
b. 
The wetland boundary shall be marked in the field (with flagging left in the field for Whatcom County verification and placed high enough to allow line of sight with vegetation growth) and surveyed using a methodology appropriate to scale of development. The surveyed wetlands areas shall be mapped showing location and size of all wetlands. Methodology used shall be in the report with description of equipment (specs), accuracy, and pertinent description of how the coordinates were gathered.
c. 
Determination of each wetland size.
d. 
Description of each wetland class and category.
e. 
Description of overall water sources and drainage patterns on site. Include all streams and drainages (Type S, F, Np, or Ns streams), shorelines, floodplains, flood-prone areas.
f. 
Description of vegetation, hydrologic conditions, and soil and substrate conditions.
g. 
Description of wildlife and habitat. Include all critical habitat for threatened and endangered species within 300 feet of the development footprint.
h. 
Topographic elevation, at two-foot contours provided by Whatcom County PDS, for single-family proposals.
i. 
Functional assessment of the wetland and adjacent buffer using a local or state agency-recognized method and including the reference of the method and all data sheets.
j. 
Standard buffer requirements for each wetland. Copies of the wetland rating forms and associated figures from the Ecology Wetland Rating System for Western Washington, as amended.
E. 
For single-family building permits, the applicant may hire a qualified professional to prepare the assessment report or may request that the county assess the regulated wetland(s) and buffers and determine the impacts associated with the project, subject to the following:
1. 
Availability of county staff shall be at the discretion of the director and subject to workload and scheduling constraints.
2. 
Fees for county staff services shall be in accordance with the Unified Fee Schedule.
F. 
If a regulated wetland buffer from a neighboring property extends onto a proposed development site for which review under this chapter is required, the director shall have the authority to require that deterrent devices be placed at the edge of the buffer in accordance with WCC § 16.16.265. The applicant shall provide documentation that no buffer encroachment will occur. The documentation shall be on a form provided by the department.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
In addition to the applicable general protective measures found in WCC § 16.16.265, activities that adversely affect wetlands and/or wetland buffers shall include mitigation sufficient to achieve no net loss of wetland function and values in accordance with WCC § 16.16.260 and this section.
A. 
In determining the extent and type of mitigation required, the director may consider all of the following when applicable:
1. 
The ecological processes that affect and influence critical area structure and function within the watershed or sub-basin;
2. 
The individual and cumulative effects of the action upon the functions of the critical area and associated watershed;
3. 
Observed or predicted trends regarding the gains or losses of specific wetland types in the watershed, in light of natural and human processes;
4. 
The likely success of the proposed mitigation measures;
5. 
Effects of the mitigation actions on neighboring properties; and
6. 
Opportunities to implement restoration actions formally identified by an adopted shoreline restoration plan, watershed planning document prepared and adopted pursuant to Chapter 90.82 RCW, a watershed plan prepared pursuant to Chapter 400-12 WAC, a salmonid recovery plan or project that has been identified on the Watershed Management Board habitat project list or by the Washington State Department of Fish and Wildlife as essential for fish and wildlife habitat enhancement, a fully authorized mitigation bank (WCC § 16.16.263), or an in-lieu-fee program.
B. 
Type of Mitigation.
1. 
Wetland Alterations. Compensatory mitigation projects shall restore, create, rehabilitate, enhance, and/or preserve equivalent wetland functions and values pursuant to no net loss of function and area. Compensation for wetland alterations shall occur in the following order of preference:
a. 
Reestablishing (also referred to as restoring) wetlands on upland sites that were formerly wetlands.
b. 
Creating wetlands on disturbed upland sites such as those consisting primarily of nonnative, invasive plant species.
c. 
Rehabilitation of existing wetlands for the purposes of repairing or restoring natural and/or historic hydrologic functions.
d. 
Enhancing existing significantly degraded wetlands.
e. 
Preserving Category I or II wetlands that are under imminent threat; provided, that preservation shall only be allowed in combination with other forms of mitigation when the director determines that the overall mitigation package fully replaces the functions and values lost due to development.
2. 
Buffer Alterations. Compensatory mitigation for buffer impacts:
a. 
Shall be consistent with WCC § 16.16.630 and § 16.16.640; and
b. 
May include enhancement of degraded buffers by planting native species, removing structures and impervious surfaces within buffers, and other measures to achieve equivalent or greater buffer functions.
C. 
Mitigation Ratios.
1. 
Compensatory mitigation for wetland alterations shall be based on the wetland category and the type of mitigation activity proposed. The replacement ratio shall be determined according to the ratios provided in Table 2; provided, that the replacement ratio for preservation shall be 10 times the ratio for reestablishment or creation. The created, reestablished, rehabilitated, or enhanced wetland area shall, at a minimum, provide a level of function equivalent to the wetland being altered and shall be located in an appropriate landscape setting.
2. 
The mitigation ratios noted in Table 2 shall not apply to mitigation banks as defined by this chapter. Credit and debit procedures for mitigation banks shall be determined in accordance with the mitigation banking provisions outlined in WCC § 16.16.263.
3. 
The director shall have the authority to adjust the mitigation ratios in Table 2 when one or more of the following apply:
a. 
When a combination of mitigation approaches is proposed. In such cases, the area of altered wetland shall be replaced at a 1:1 ratio through reestablishment or creation, and the remainder of the area needed to meet the ratio can be replaced by enhancement or rehabilitation using Table 2.
b. 
When the project proponent has a demonstrated ability, based on past performance, to successfully design, construct, monitor and maintain wetland mitigation projects/sites.
c. 
When use of the guidance for Calculating Credits and Debits for Compensatory Mitigation in Wetlands of Western Washington (Department of Ecology Publication No. 10-06-011, as amended) results in a lower mitigation ratio than the standard ratios.
4. 
For permanent impacts to wetland buffers, unless the director approves a habitat management plan with different ratios, mitigation shall be provided at the following ratios:
a. 
Where the mitigation is in place and functional before the impact occurs (i.e., advanced mitigation), at a ratio determined by the functions, values, and goals of an advanced mitigation plan.
b. 
Where the mitigation is in place within one year of the impact occurring, at a 1:1 ratio (area or function).
c. 
Where the mitigation is placed after one year of the impact occurring, at a 1.25:1 ratio (area or function).
d. 
For retroactive permits the director may require the ratio to be up to double the ratio in subsection (C)(4)(c) of this section.
Table 2. Mitigation Ratios for Projects in Western Washington[1]
Category and Type of Wetland Impacts
Reestablishment or Creation
Rehabilitation Only
Reestablishment or Creation (R/C) and Rehabilitation (RH)
Reestablishment or Creation (R/C) and Enhancement (E)
Enhancement Only
All Category IV
1.5:1
3:1
1:1 R/C and
1:1 RH
1:1 R/C and
2:1 E
6:1
All Category III
2:1
4:1
1:1 R/C and
2:1 RH
1:1 R/C and
4:1 E
8:1
Category II Estuarine
Case-by-case
4:1 Rehabilitation of an estuarine wetland
Case-by-case
Case-by-case
Case-by-case
All other Category II
3:1
6:1
1:1 R/C and
4:1 RH
1:1 R/C and
8:1 E
12:1
Category I
No alteration allowed unless an essential public facility
(Ratios indicate mitigation area to area disturbed.)
[1]
From Wetlands in Washington, Volume 2, Appendix 8C, Guidance on Widths of Buffers and Ratios for Compensatory Mitigation for Use with the Western Washington Wetland Rating System, Table 8C-11.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))
A. 
In addition to meeting the requirements of WCC § 16.16.260(B), a mitigation plan for wetland and wetland buffer impacts shall meet the following:
1. 
Provide an analysis of existing wetland functions and values and a detailed description of the effects of the proposed development on wetland and buffer function and value, including the area of direct wetland disturbance, area of buffer disturbance, area of buffer reduction, and area of buffer averaging, including documentation that the functions and values will be increased through reduction or average; effects of stormwater management; proposed hydrologic alteration including changes to natural drainage or infiltration patterns; effects on fish and wildlife species and their habitats; clearing and grading impacts; temporary construction impacts; and effects of increased noise, light, and human intrusion.
2. 
The plan shall be based on applicable portions of the Washington State Department of Ecology's Guidelines for Developing Freshwater Wetland Mitigation Plans and Proposals, 2004, or other appropriate guidance document that is consistent with best available science.
3. 
The plan shall contain sufficient information to demonstrate that the proposed activities are logistically feasible, constructible, ecologically sustainable, and likely to succeed. Specific information to be provided in the plan shall include:
a. 
The rationale for site selection;
b. 
General goals of the plan, including wetland function, value, and acreage;
c. 
Description of baseline (existing) site conditions including topography, vegetation, soils, hydrology, habitat features (e.g., snags), surrounding land use, and other pertinent information;
d. 
Field data confirming the presence of adequate hydrology (surface and/or groundwater) to support existing and mitigated wetland area(s);
e. 
Nature of mitigation activities, including area of restored, created, enhanced, rehabilitated and preserved wetland, by wetland type;
f. 
Detailed grading and planting plans showing proposed post-construction topography; general hydrologic patterns; spacing and distribution of plant species; size and type of proposed planting stock; watering or irrigation plans; and other pertinent information;
g. 
To facilitate establishment of a stable community of native plants, a description of site treatment measures, including removal of noxious weeds and/or invasive species, use of mulch and fertilizer, placement of erosion and sediment control devices, and best management practices that will be used to protect existing wetlands and desirable vegetation;
h. 
A demonstration that the site will have adequate buffers sufficient to permanently protect the wetland functions.
B. 
All mitigation projects shall be monitored in accordance with WCC § 16.16.260(H) for a period necessary to establish that performance standards have been met. The director shall have the authority to extend the monitoring period for up to 10 years and require additional monitoring reports when any of the following conditions apply:
1. 
The project does not meet the performance standards identified in the mitigation plan.
2. 
The project does not provide adequate replacement for the functions and values of the impacted critical area.
3. 
The project involves establishment of forested plant communities, which require longer time for establishment.
C. 
Reports shall be submitted annually for the first three years following construction and at the completion of years five, seven and 10 if applicable to document milestones, successes, problems, and contingency actions of the mitigation.
(Ord. 2005-068 § 1; Ord. 2017-077 § 1 (Exh. A); Ord. 2024-047 § 2 (Exh. F))