A. Applicability.

1. This chapter applies to:

a. All wetlands designated pursuant to subsection B of this section.

b. All wetland buffers as shown in the tables in subsection I of this section.

B. Identification and Designation.

1. Identification of wetlands and delineation of their boundaries pursuant to this chapter shall be done in accordance with the federal wetland delineation manual and applicable regional supplements (as updated), as required by WAC 173-22-035. All areas within the city meeting the wetland designation criteria, regardless of any formal delineation, are hereby designated as wetlands and are subject to provisions of this chapter unless specified in BIMC 16.20.190.

2. Wetland delineations shall be conducted by a qualified professional, in accordance with BIMC 16.20.070.

3. The wetland boundary shall be marked in the field and surveyed by a licensed surveyor. The surveyed wetlands shall be sized and mapped on a scaled site plan. The director may require the wetland delineation to be verified in the field by the Army Corps of Engineers or the Washington State Department of Ecology when there is uncertainty in the wetland boundary or there was unauthorized wetland disturbance. The requirement for a licensed surveyor to survey the wetland boundaries may be waived in limited circumstances, such as when there is no access to the wetland property or there is no proposed impact to the wetland and wetland buffer, with authorization from the director.

4. Wetland delineations shall be valid for five years from the date of the delineation.

5. A wetland delineation shall be required for any proposed development within 300 feet of a designated wetland. If any portion of the designated wetland is on a different site than the proposed development, the location of the wetland boundary may be determined using best professional judgment.

C. Wetland Categories. Wetlands shall be rated according to the Washington State Wetland Rating System for Western Washington – 2014 Update (Ecology Publication No. 14-06-029, October 2014), as revised. The wetland categories determined by the rating are as follows:

1. Category I wetlands are:

a. Relatively undisturbed estuarine wetlands larger than one acre;

b. Wetlands that are, or may be in the future, identified by scientists of the Washington Natural Heritage Program/Department of Natural Resources as wetlands of high conservation value;

c. Bogs;

d. Mature forested wetlands larger than one acre;

e. Wetlands in coastal lagoons; and

f. Wetlands that perform many functions well and score 23 points or more in the wetland rating. These wetlands are those that represent a unique or rare wetland type, are more sensitive to disturbance than most wetlands, or are relatively undisturbed and contain ecological attributes that are impossible to replace within one human lifetime.

2. Category II wetlands are:

a. Wetlands with a moderately high level of functions and score 20 to 22 points in the wetland rating.

b. Estuarine wetlands smaller than one acre or disturbed estuarine wetlands larger than one acre.

3. Category III wetlands are:

a. Wetlands with a moderate level of functions and score between 16 to 19 points in the wetland rating.

4. Category IV wetlands are:

a. Wetlands with a low level of functions, scoring less than 16 points in the wetland rating.

5. Date of Wetland Rating. The wetland rating categories in this section shall be applied to wetland studies including but not limited to delineations, on or after the date of adoption of the ordinance codified in this chapter. The wetland rating shall be valid for five years unless the state rating system changes or the wetland and/or the wetland buffer have been altered since the rating.

6. A wetland rating pursuant to subsection C of this section shall be required for any proposed development within 300 feet of a designated wetland. If any portion of the designated wetland is on a different site than the proposed development, the rating may be determined using best professional judgment.

7. Illegal Modifications. Wetland rating categories shall not change due to illegal modifications.

D. Mapping. The location and extent of all mapped critical areas shown on the city of Bainbridge Island critical area maps are approximate and shall be used as a general guide only. The type, extent and boundaries shall be determined in the field by a qualified professional according to the requirements of this chapter. The critical area maps (http://www.bainbridgewa.gov/196/GIS-Mapping-Map-Gallery) are adopted as part of this chapter and are incorporated herein by this reference. In addition, the National Wetlands Inventory and Soil Maps produced by the U.S. Department of Agriculture, National Resources Conservation Service may be useful in helping to identify potential wetland areas. The inventory and cited resources are to be used as a guide for the city, project applicants, and property owners, and may be continuously updated as new or altered critical areas are identified.

E. Protection of Wetlands.

1. Any action taken pursuant to this chapter shall result in equivalent or greater functions and values of the wetlands and wetland buffers associated with the proposed action, as determined by the best available science. All actions and developments shall be designed and constructed in accordance with mitigation sequencing as described in BIMC 16.20.030 and WAC 197-11-768.

2. Applicants must first demonstrate an inability to avoid or reduce impacts, before compensation of impacts will be allowed. No activity or use shall be allowed that results in a net loss of the functions or values of critical areas.

3. Permanent protection of critical areas that are part of an approved mitigation plan or buffer enhancement plan shall be achieved through a notice to title recorded at the Kitsap County auditor’s office, or similar means of protection in perpetuity.

F. Permit and Review Procedures.

1. Any development, use or activity within any wetland and/or its required buffer shall require a critical area permit unless it qualifies as an exempt activity, as provided in BIMC 16.20.040.

2. Critical area permits shall be reviewed pursuant to the criteria in BIMC 16.20.070.

3. Applications for critical area permits for wetlands shall include:

a. City of Bainbridge Island master land use application (http://www.bainbridgewa.gov/161/Documents-Forms-Applications); and

b. Wetland critical areas report prepared in accordance with BIMC 16.20.180.F if wetland or buffers occur within or adjacent to the project site; and

c. Wetland mitigation report, prepared in accordance with BIMC 16.20.180.G, if wetland and buffer impacts are anticipated; or

d. Buffer enhancement plan, prepared in accordance with BIMC 16.20.180.D, if only buffer modification is requested.

G. Prohibited Activities.

1. The following development, uses and activities are prohibited in all wetlands:

a. Draining, excavation, placement of fill material and flooding not associated with an exempt or regulated use;

b. Forest Practices – Class IV general or conversion option harvest plan;

c. New or expanded agriculture; or

d. On-site sewage facility.

2. The following development, uses and activities are prohibited in Category I and II wetlands:

a. Fish hatchery;

b. Golf course;

c. Mineral extraction;

d. Public facility;

e. Public communications tower;

f. New public road/street;

g. New private access road or driveway;

h. Stormwater retention/detention facility; or

i. Primary utility. Exceptions for electric transmission and distribution lines may apply under BIMC 16.20.050.D for existing development or under BIMC 16.20.140.H.5 for new development.

H. Standards for Specific Development, Uses and Activities. The following development, uses and activities may be allowed within wetlands and their required buffers. Any proposal for the following development, uses and activities requires a critical area permit pursuant to subsection F of this section and shall comply with the standards of this section and other applicable state, federal and local regulations.

1. Road/Street Repair and Construction. Any private or public road or street repair, maintenance, expansion or construction may be allowed within a wetland or its required buffer only when all of the following conditions are met:

a. No other reasonable or practicable alternative exists and the road or street crossing serves multiple properties whenever possible;

b. Publicly owned or maintained road or street crossings should provide for other purposes, such as utility crossings, pedestrian or bicycle easements, viewing points, etc.;

c. The road or street repair and construction are the minimum necessary to provide safe roads and streets; and

d. Mitigation shall be performed in accordance with specific project mitigation plan requirements.

2. Land Divisions and Land Use Permits. All land divisions and land uses proposed on a site that includes regulated wetlands shall comply with the procedures and standards listed below. When a parcel contains a wetland, city policy shall always be to primarily protect the functions and values of the wetland, while recognizing the value of the development rights provided to the property by its zoning.

a. Density Calculation.

i. The actual density that will be allowed to be built upon a parcel containing a wetland shall ultimately be determined during the site specific review of the parcel’s planned development;

ii. In determining the actual density of a parcel based on a specific site plan, the site plan shall locate all buildings outside of any wetland and its required buffers;

iii. The number of development rights allowed for any residentially-zoned parcel shall be its size in square feet divided by the number of square feet per home that is required by its zoning;

iv. If the land can be subdivided such that all setbacks, buffers, and other zoning requirements can be observed, and no zoning variances are requested, the density from the wetland, except the area with permanent open water, can be transferred within the property;

v. To the extent that the number of allowable development rights cannot be used on site, they may be sold, traded, or transferred by the property owner through the transfer of development rights program pursuant to Chapter 18.27 BIMC;

vi. Property owners may voluntarily extinguish development rights that are provided by the underlying zoning, but the city shall not extinguish any of these rights outside the aforementioned transactions.

b. Land division approvals shall be conditioned to require that wetlands and wetland buffers be designated as an easement or covenant encumbering the wetland and wetland buffer. Such easement or covenant shall be recorded together with the land division and represented on the final plat or binding site plan, and title.

c. In order to implement the goals and policies of this chapter, to accommodate innovation, creativity, and design flexibility, and to achieve a level of environmental protection that would not be possible by typical lot-by-lot development, the use of the clustered development or similar innovative site planning is strongly encouraged for projects with regulated wetlands on the site.

3. Surface Water Management. Surface water structures or discharges from stormwater facilities may be allowed within wetlands and their required buffers only when the applicant has an approved site assessment review (SAR) pursuant to the requirements of Chapter 15.20 BIMC and the proposal meets criteria in Appendix I-D, Guidelines for Wetlands when Managing Stormwater, from Washington State Department of Ecology’s 2012 Stormwater Management Manual for Western Washington, as amended in 2014.

4. Trails and Trail-Related Facilities. Construction of public and private trails and trail-related facilities, such as benches and viewing platforms, are allowed in wetlands or wetland buffers only when the following standards are met:

a. Trails and related facilities shall be placed on existing road grades, utility corridors, or any other previously disturbed areas if present at the site and consistent with trail planning objectives.

b. Trails and related facilities shall be planned to minimize removal of trees, soil disturbance, and maintain existing hydrological characteristics, shrubs, snags, and important wildlife habitat.

c. Viewing platforms and benches, and access to them, shall be designed and located to minimize disturbance of wildlife habitat and/or critical characteristics of the affected wetland. Viewing platforms shall be limited to 100 square feet in size, unless demonstrated through a wetland critical areas report and mitigation plan that a larger structure will not result in a net loss of wetland functions.

d. Trail planning shall utilize mitigation sequencing in BIMC 16.20.030 to first avoid siting trail and trail-related facilities within wetlands and their required buffers. Trails and trail-related facilities are allowed within wetlands or wetland buffers if there are no reasonable alternatives for meeting an applicant’s trail planning objectives and it is demonstrated through a wetland critical areas report and mitigation plan that the proposal will not result in a net loss of wetland functions.

e. Trails shall be limited to nonmotorized use. Trail width shall not exceed six feet unless there is a demonstrated need, subject to review and approval by the director. Trails shall be constructed with pervious materials unless otherwise approved by the director.

5. Utilities. Installation of utilities within wetlands or their required buffers may be allowed when the following standards are met:

a. Construction of new utilities outside the road right-of-way or an existing utility corridor may be permitted in wetlands or wetland buffers only when no reasonable alternative location is available and the utility meets the requirements for installation, replacement of vegetation and maintenance outlined below, and as required in the filing and approval of applicable permits and special reports required by this chapter.

b. Sewer or On-Site Sewage Utility. Construction of sewer lines or on-site sewage systems may be permitted in wetland buffers only when:

i. The applicant demonstrates it is necessary to meet state and/or local health code minimum design standards (not requiring a variance for either horizontal setback or vertical separation); and/or

ii. There are no other practicable or reasonable alternatives available and construction meets all other applicable requirements of this section. Joint use of the sewer utility corridor by other utilities may be allowed.

c. New utilities shall not be allowed when the wetland or buffer has known locations of federal- or state-listed endangered, threatened, monitored or sensitive species, heron rookeries or nesting sites of raptors which are listed as species of concern, except in those circumstances where an approved habitat management plan indicates that the utility corridor will not significantly impact the wetland or wetland buffer.

d. New utility construction and maintenance shall protect the wetland and buffer environment by utilizing the following methods:

i. New utilities shall be aligned to avoid tree removal to the greatest extent practicable.

ii. Any area of disturbance resulting from installation of a utility shall be revegetated with appropriate native or equivalent vegetation at preconstruction densities or greater, immediately upon completion of construction, or as soon thereafter as possible, if due to seasonal growing constraints. The utility or landowner responsible for installation shall ensure that such vegetation survives.

iii. Any access for maintenance shall be provided as much as possible at specific points, rather than by parallel roads. If parallel roads are necessary, they shall be of a minimum width but no greater than 15 feet; and shall be contiguous to the location of the utility corridor on the side away from the wetland. Mitigation will be required for any additional access through restoration of vegetation in disturbed areas.

iv. The director may require additional mitigation measures.

v. Utility maintenance shall include the following measures to protect the wetland and buffer environment:

A. Painting of utility equipment such as power towers shall not be sprayed or sandblasted. Lead-based paints are prohibited.

B. No pesticides, herbicides or fertilizers may be used in wetland areas or their buffers except those approved by the U.S. Environmental Protection Agency (EPA) and Washington Department of Ecology and applied by a licensed applicator in accordance with the safe application practices on the label.

e. Construction of new distribution and transmission utility lines in Category III and IV wetlands shall follow the provisions in subsections H.5.a through H.5.d of this section. Construction of new distribution and transmission lines may be permitted in Category II wetlands and their buffers provided all the other applicable sections of this chapter are met, and:

i. The applicant demonstrates that the inability to impact Category II wetlands would unnecessarily restrict the ability to provide utility services to the public;

ii. There is no practicable alternative location with less adverse impact on the functions and values of the impacted Category II wetland.

iii. Construction of the utility where impacts to a Category II wetland cannot be avoided is within or directly adjacent to an existing road right-of-way;

iv. The construction of new distribution and transmission utility lines does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site; and

v. The construction of new distribution and transmission utility lines avoids and minimizes the impact on critical areas in accordance with required mitigation sequencing and demonstrates no net loss as described in BIMC 16.20.030, and is consistent with best available science.

6. Parks. Development of public park and recreation facilities may be allowed; provided, that no alteration of wetlands or wetland buffers is allowed except as allowed in BIMC 16.20.040 (Exemptions) and this subsection H (Standards for Specific Development, Uses and Activities).

I. Wetland Buffers.

1. Buffers shall remain as undisturbed or enhanced vegetation areas for the purpose of protecting the integrity, function, and value of wetland resources. Any buffer modification proposed shall be through an approved buffer enhancement plan meeting the requirements of BIMC 16.20.180. No uses or activities shall be allowed within the buffer unless allowed by this section. If a buffer on a site subject to land use review or a building permit application has previously been disturbed, the director may require the disturbed buffer area be enhanced, including revegetation with native plant species, pursuant to an approved buffer enhancement plan meeting the requirements of BIMC 16.20.180. No refuse, including but not limited to household trash, yard waste and commercial/industrial refuse, shall be placed in the buffer.

2. All regulated wetlands shall be surrounded by a buffer, based upon Appendix 8-C, Section 8C.2.3 of Wetlands in Washington State – Volume 2: Guidance for Protecting and Managing Wetlands (Ecology Publication No. 05-06-008), as amended. Standard buffer widths are shown in Tables 3 through 6 of this section. If a wetland meets more than one of the criteria listed in each table, the buffer needed to protect the wetland is the widest one.

3. Standard buffer widths are based on impact of land use, which is categorized as follows:

a. High impact land use includes commercial development, industrial development, institutional development, residential (all residential zoning classifications other than R-0.4, R-1 and R-2) development, new agriculture (high-intensity such as dairies, nurseries, greenhouses, raising and harvesting crops requiring annual tilling, raising and maintaining animals), forestry activities, and high-intensity recreation such as golf courses and ballfields.

b. Moderate impact land use includes residential development (R-0.4, R-1 and R-2 residential zoning classifications), new agriculture (moderate-intensity such as orchard and hay fields), paved trails, and construction of temporary logging roads.

c. Low impact land use includes low-intensity open space such as passive recreation, natural resources preservation, and unpaved trails.

4. The required minimum buffers listed in Tables 3 through 6 of this section are based on the assumption that the buffer is well vegetated with native species appropriate to the site. If the buffer does not consist of vegetation adequate to provide wetland protection and buffer functions, the director may require that the buffer be planted to achieve such protection and function.

Table 3: Category I Wetlands – Buffers 

Wetland Characteristics	Impact of Land Use	Buffer Width	Other Protection
Natural Heritage Wetlands	Low Moderate High	125 ft 190 ft 250 ft	No additional discharge of surface water. No septic systems within 300 ft. Restore degraded parts of the buffer.
Bogs	Low Moderate High	125 ft 190 ft 250 ft	No additional surface discharges. Restore degraded parts of the buffer.
Forested	Low Moderate High	125 ft 190 ft 250 ft	If forested wetland scores high for habitat, maintain connectivity to other natural areas.
Estuarine	Low Moderate High	100 ft 150 ft 200 ft	N/A
Wetlands in Coastal Lagoon	Low Moderate High	100 ft 150 ft 200 ft	N/A
High level of function for habitat (score for habitat is 8–9 points)	Low Moderate High	150 ft 225 ft 300 ft	Maintain connectivity to other natural areas. Restore degraded parts of the buffer.
Moderate level of function for habitat (score for habitat is 5–7 points)	Low Moderate High	75 ft 110 ft 150 ft	N/A
High level of function for water quality improvement and low for habitat (score for water quality points, habitat less than 5 points)	Low Moderate High	50 ft 75 ft 100 ft	No additional discharges of untreated runoff.
Not meeting any of the above criteria	Low Moderate High	50 ft 75 ft 100 ft	N/A

Table 4: Category II Wetlands – Buffers 

Wetland Characteristics	Impact of Land Use	Buffer Width	Other Protection
High level of function for habitat (score for habitat is 8–9 points.)	Low Moderate High	150 ft 225 ft 300 ft	Maintain connectivity to other natural areas.
Moderate level of function for habitat (score for habitat is 5–7 points.)	Low Moderate High	75 ft 110 ft 150 ft	N/A
Estuarine	Low Moderate High	75 ft 110 ft 115 ft	N/A
Not meeting any of the above criteria	Low Moderate High	50 ft 75 ft 100 ft	N/A

Table 5: Category III Wetlands – Buffers 

Wetland Characteristics	Impact of Land Use	Buffer Width	Other Protection
Moderate level of function for habitat (score for habitat is 5–7 points.)	Low Moderate High	75 ft 110 ft 150 ft	N/A
Not meeting above criterion	Low Moderate High	40 ft 60 ft 80 ft	N/A

Table 6: Category IV Wetlands – Buffers 

Wetland Characteristics	Impact of Land Use	Buffer Width	Other Protection
All	Low Moderate High	25 ft 40 ft 50 ft	N/A

5. Buffer Measurement. All buffers shall be measured on a horizontal plane from the delineated wetland edge as marked in the field by a qualified professional.

6. Fencing and Signs. This section applies to those wetlands and their buffers that are within 200 feet of regulated development activities.

a. Wetland buffers shall be temporarily fenced or otherwise suitably marked between the area where the construction activity occurs and the buffer. Fences shall be made of a durable protective barrier and shall be highly visible. Silt fences and plastic construction fences may be used to prevent encroachment on wetlands or their buffers by construction. Temporary fencing shall be removed after the site work has been completed and the site is fully stabilized per city approval.

b. The director may require that permanent signs and/or fencing be placed on the common boundary between a wetland buffer and the adjacent land. Such signs will identify the wetland buffer. The director may approve an alternate method of wetland and buffer identification, if it provides adequate protection to the wetland and buffer.

7. Structure or Hard Surface Setback. A structure or hard surface setback line of 15 feet is required from the edge of any wetland buffer. Minor structural or impervious surface intrusions into the areas of the setback, such as but not limited to fire escapes, open/uncovered porches, landing places, outside walkways, outside stairways, retaining walls, fences and patios, may be permitted if the department determines upon review of an analysis of buffer functions submitted by the applicant, that construction and/or maintenance of such intrusions will not encroach into the wetland buffer or adversely impact the wetland. The functional analysis shall include a functional methodology supported by best available science. The setback shall be identified on a site plan and filed as an attachment to the notice on title as required by BIMC 16.20.070.G (Notice on Title).

8. Buffer Modification. On each site, only one of the following modifications to buffer widths may be allowed provided the applicant demonstrates the need for modification through mitigation sequencing pursuant to BIMC 16.20.030 and the modification that results in the retention of the greatest area of buffer is used.

a. Buffer Width Averaging. The width of a required buffer may be averaged if the applicant can demonstrate that averaging can provide equal or greater functions and values as would be provided under the required buffer and all of the following conditions are met:

i. The total area of buffer after averaging is equal to the area required without averaging.

ii. Averaging cannot result in any portion of the buffer being reduced more than 25 percent of its required width.

b. Buffer Width Reduction. The width of a required buffer may be reduced if the applicant can demonstrate that the reduction will provide equal or greater functions and values as would be provided under the required buffer and that this will improve the protection of wetland functions and all of the following conditions are met:

i. The buffer may not be reduced more than 25 percent of its required width.

ii. Native vegetation on other portions of the site is retained in order to offset habitat loss from buffer reduction.

c. The required buffer widths for proposed land uses with high-intensity impacts to wetlands may be reduced to those required for moderate-intensity impacts under the following conditions:

i. For wetlands that score moderate or high for habitat (five points or more for the habitat function), the width of the buffer may be reduced if both of the following criteria are met:

A. A relatively undisturbed, vegetated corridor at least 100 feet wide is provided if the wetland contains any priority habitats as defined by the Washington Department of Fish and Wildlife. “Relatively undisturbed” and “vegetated corridor” are defined in the Western Washington Wetland Rating System. The corridor must be protected for the entire distance between the wetland and the priority habitat by some type of legal protection, such as a notice to title.

B. Measures to minimize the impacts of different land uses on wetlands, such as the examples in Table 7 of this section, are applied.

ii. For wetlands that score less than five points for habitat, the buffer width may be reduced to that required for moderate land use impacts by applying measures to minimize the impacts of different land uses on wetlands, such as the examples in Table 7 of this section.

d. Any request for buffer modification outlined above shall be reviewed in conjunction with the underlying land use or construction permit. A critical area permit is not required. Requests for buffer averaging or buffer reduction shall include a buffer enhancement plan prepared by a qualified professional that meets the requirements of BIMC 16.20.180.D. Buffer enhancement plans shall be reviewed pursuant to the criteria in BIMC 16.20.070.

e. Any other buffer modification resulting in a reduced buffer area, other than noncompensatory enhancement, requires a reasonable use exception pursuant to BIMC 16.20.080.

Table 7: Examples of Measures to Minimize Impacts to Wetlands  

from Different Types of Activities 

Examples of Disturbance	Examples of Measures to Minimize Impacts	Activities that Cause the Disturbance
Lights	• Direct lights away from wetland.	Parking lots, warehouses, manufacturing, residential
Noise	• Locate activity that generates noise away from wetland. • If warranted, enhance existing buffer with native vegetation plantings adjacent to noise source. • For activities that generate relatively continuous, potentially disruptive noise, such as heavy industry or manufacturing, establish an additional 10-foot heavily vegetated buffer strip immediately adjacent to the outer wetland buffer.	Manufacturing, residential
Toxic runoff*	• Route all new runoff away from wetland. • Establish covenants limiting use of pesticides within 150 feet of wetland. • Apply integrated pest management.	Parking lots, roads, manufacturing, residential areas, application of agricultural pesticides, landscaping
Stormwater runoff	• Retrofit stormwater detention and treatment for roads and existing adjacent development. • Prevent channelized flow from lawns that directly enters the buffer. • Use low impact development techniques consistent with Chapter 15.20 BIMC.	Parking lots, roads, manufacturing, residential areas, landscaping
Change in water regime	Infiltrate or treat, detain, and disperse new runoff into buffer.	Impermeable surfaces, lawns, tilling
Pets and human disturbance	• Plant buffer with dense, impenetrable native vegetation appropriate for region. • Install low impact fencing at buffer perimeter. • Place wetland and its buffer in separate open space tract or protect with conservation easement.	Residential areas
Dust	Utilize best management practices to control dust.	Tilled fields
*These examples are not necessarily adequate to meet the rules for minimizing toxic runoff if threatened or endangered species are present at the site.

J. Wetland Mitigation Requirements.

1. Mitigation Sequencing. All development, uses and activities proposed to impact wetlands shall be mitigated according to this section and the mitigation sequencing steps outlined in BIMC 16.20.030. The applicant shall demonstrate to the satisfaction of the director that each step of mitigation sequencing has been adequately addressed prior to approval of impacts to wetlands.

2. Compensatory mitigation shall be required for development, uses or activities that result in the loss of wetland acreage or in the reduction of wetland functions or values.

3. Mitigation Report. Where mitigation is required under the sequencing in subsection J.1 of this section, a mitigation plan is a required component of a critical areas report meeting the requirements in BIMC 16.20.180, Critical area reports.

4. Wetland Replacement.

a. The ratios shown in Table 8 of this section shall be used to determine the required amount of wetland mitigation. The first number specifies the amount of wetland area to be restored, rehabilitated, created or enhanced, and the second number specifies the amount of wetland area lost. The director may decrease these ratios when there are findings of special studies coordinated with agencies with expertise which demonstrate that no net loss of wetland function or value is attained under the decreased ratio.

b. Mitigation requirements may also be determined using the credit/debit tool described in Calculating Credits and Debits for Compensatory Mitigation in Wetlands of Western Washington: Final Report (Ecology Publication No. 10-06-011, March 2012, or as revised) consistent with Table 8 of this section.

Table 8: Replacement Ratios for Wetlands 

Category and Type	Reestablishment or Creation	Rehabilitation	1:1 Reestablishment or Creation (R/C) and Enhancement (E)	Enhancement Only
I – Mature Forested	6:1	12:1	1:1 R/C and 10:1 E	24:1
I – Based on functions	4:1	8:1	1:1 R/C and 6:1 E	16:1
I – Bog or Natural Heritage Site	Not considered possible	6:1	Case by case	Case by case
II	3:1	6:1	1:1 R/C and 4:1 E	12:1
III	2:1	4:1	1:1 R/C and 2:1 E	8:1
IV	1.5:1	3:1	1:1 R/C and 2:1 E	6:1

5. Approaches to Compensatory Mitigation.

a. Compensatory mitigation may occur at the site of the allowed impacts or at an off-site location. Considerations for determining whether off-site mitigation is preferable include, but are not limited to, one or more of the following:

i. On-site conditions do not favor mitigation success due to soil conditions, hydrology or adverse impacts of adjacent land uses;

ii. On-site conditions are isolated from other aquatic or riparian habitats;

iii. An off-site location is beneficial to larger ecosystem or watershed functions;

iv. An off-site location has greater likelihood of success or will provide greater functional benefits;

v. The proposal for an off-site location uses a watershed approach consistent with Selecting Wetland Mitigation Sites Using a Watershed Approach (Western Washington) (Ecology Publication No. 09-06-32, December 2009).

b. Off-site compensatory mitigation may include the use of a wetland mitigation bank or an in-lieu fee program, if such instruments are available within the city limits.

c. Advanced Mitigation. Compensatory mitigation in advance of proposed impacts may be allowed on a case-by-case basis for projects with preidentified impacts consistent with Interagency Regulatory Guide: Advance Permittee-Responsible Mitigation (Ecology Publication No. 12-06-015, December 2012).

6. Monitoring Requirements. The city shall require monitoring reports on an annual basis for a minimum of five years and up to 10 years, or until the director determines the mitigation project has met the performance standards specified in the wetland mitigation plan. The wetland mitigation plan shall provide specific performance standards for monitoring the mitigation project. Performance standards shall be project-specific and use best available science to aid the director in evaluating whether or not the project has achieved success. (Ord. 2024-04 §§ 3, 4, 2024; Ord. 2018-01 § 2 (Exh. A), 2018)