22.08.060 Critical area regulations for wetlands within the shoreline jurisdiction

22.08.060 Critical area regulations for wetlands within the shoreline jurisdiction.

All land use and development including, but not limited to, clearing, grading, construction of infrastructure, buildings, facilities, accessories and appurtenances that are proposed, developed, occupied and operated within wetlands regulated under BMC 16.55.270 or their buffers shall comply with the following regulations. Wetland ratings shall be established in accordance with BMC 16.55.280.

A. Measurement of Wetland Buffers. All buffers shall be measured horizontally from edge of the wetland boundary as surveyed in the field. The width of the wetland buffer shall be determined according to Tables 1, 2, and 3 below.

B. Buffer Standards. The buffer standards required by this title presume the existence of a dense 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, requiring buffer planting or enhancement, and/or deny a proposal for buffer reduction or buffer averaging.

The standard buffer shall be based on the wetland category, the adjacent land use, and the functions provided by the wetland. There are three sets of buffer standards, based on these parameters:

1. For wetlands that have a high level of function for wildlife habitat as indicated by a habitat function score of 29 points or more on the wetland rating form, the buffers shall be as follows:

Table 1	Buffer Width (feet)
Wetland Category	High Intensity	Moderate Intensity	Low Intensity
Category I	200	190	150
Category II	200	150	100
Category III	150	110	75
Category IV	50	40	25
Definitions for high-, moderate- and low-intensity land use are provided in Chapter 22.10 BMC.

2. For wetlands that have a moderate level of function for wildlife habitat as indicated by a habitat function score of 20 to 28 points on the wetland rating form, the buffer shall be as follows:

Table 2	Buffer Width (feet)
Wetland Category	High Intensity	Moderate Intensity	Low Intensity
Category I	150	110	75
Category II	150	110	75
Category III	150	100	60
Category IV	50	40	25
Definitions for high-, moderate- and low-intensity land use are provided in Chapter 22.10 BMC.

3. For wetlands that have a low level of function for wildlife habitat as indicated by a habitat function score of less than 20 points on the wetland rating form, the buffers shall be as follows:

Table 3	Buffer Width (feet)
Wetland Category	High Intensity	Moderate Intensity	Low Intensity
Category I	100	75	50
Category II	100	75	50
Category III	80	60	50
Category IV	50	40	25
Definitions for high-, moderate- and low-intensity land use are provided in Chapter 22.10 BMC.

C. Modifications to Buffer Widths. Any modifications to the buffer width are to be based on the specific wetland functions, site and/or watershed characteristics, and location of the wetland within the watershed or sub-basin, and the proposed land use.

1. Increasing Buffer Widths. The director shall have the authority to increase the standard buffer width on a case-by-case basis when a larger buffer is required by an approved habitat management plan as outlined in BMC 22.06.100, Permit revisions; or such increase is necessary to:

a. Protect the function and value of that wetland, including but not limited to compensating for a poorly vegetated buffer that has a steep slope (greater than 30 percent); or

b. Prevent wind-throw damage; or

c. Maintain viable populations of species such as herons and other priority or fish and wildlife; or

d. Protect wetlands or other critical areas from landslides, erosion or other hazards.

2. Reducing Wetland Buffer Widths. The director shall have the authority to reduce the standard buffer widths; provided, that all of the following apply and, provided further, that proposed reductions to less than the minimum buffer stated herein shall require approval of a shoreline variance:

a. The buffer of a Category I wetland shall not be reduced;

b. The buffer reduction shall not adversely affect the functions and values of the adjacent wetlands;

c. The buffer of a Category II or III wetland shall not be reduced to less than 75 percent of the required buffer or 50 feet, whichever is greater;

d. The buffer of a Category IV wetland shall not be reduced to less than 50 percent of the required buffer, or 25 feet, whichever is greater; and

e. The applicant implements all reasonable measures to reduce the adverse effects of adjacent land uses and ensure no new loss of buffer functions and values. The specific measures that shall be implemented include, but are not limited to, the following:

i. Direct lights away from the wetland and buffer;

ii. Locate facilities that generate substantial noise (such as some manufacturing, industrial and recreational facilities) away from the wetland and buffer;

iii. Establish covenants limiting use of pesticides and fertilizers within 150 feet of the wetland;

iv. Implement integrated pest management programs;

v. Infiltrate or treat, detain and disperse runoff into buffer;

vi. Construct a wildlife permeable fence around buffer and post 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 city;

vii. Plant buffer with “impenetrable” native vegetation appropriate for the location;

viii. Use low impact development techniques to the greatest extent possible;

ix. Establish and record a permanent conservation easement to protect the wetland and the associated buffer.

3. Averaging Buffer Widths. The director has the authority to average wetland buffer widths on a case-by-case basis when all the following criteria are met:

a. The buffer averaging does not reduce the functions or values of the wetland;

b. The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer, and all increases in buffer dimension for averaging must be parallel to the wetland boundary;

c. The wetland contains variations in sensitivity due to existing physical characteristics or the character of the buffer varies in slope, soils, or vegetation;

d. The buffer width is not reduced in any location to less than 50 percent of the standard width or 35 feet, whichever is greater, except for buffers for Category IV wetlands, and low-intensity land uses in which case the narrowest buffer width can be determined on a case-by-case basis;

e. The buffer has not been reduced in accordance with subsection (C)(2) of this section. Buffer averaging is not allowed if the buffer has been reduced; and

f. There were no feasible alternatives to the site design without buffer averaging.

D. Buffer Maintenance. Final buffer conditions shall be maintained and undisturbed from future impacts.

E. Buffer Impacts. Where impacts to buffers cannot be avoided and where buffer reduction and averaging are not sufficient or appropriate to offset buffer impacts, compensatory mitigation shall be provided. Compensatory mitigation for buffer impacts shall follow the requirements of BMC 22.08.020, Mitigation sequencing.

F. Buffers on Mitigated Sites. All mitigation sites shall have buffers consistent with the buffer requirements of this chapter and based on expected category of the wetland once the mitigation actions are taken.

G. Building Setbacks from Buffers. Unless otherwise provided, buildings and other structures shall be set back a distance of 15 feet from the edges of all wetland buffers or from the edges of wetlands, if no buffers are required, to the extent that the critical root zone of trees in the buffer are not disturbed. The following may be allowed in the building setback area:

1. Landscaping;

2. Uncovered decks;

3. Roof eaves and overhangs;

4. Pervious unroofed stairways and steps;

5. Impervious ground surfaces, such as driveways and patios; provided, that such improvements may be subject to water quality regulations.

H. Stormwater management facilities are not allowed in wetland buffers, with the following exceptions:

1. Conveyance systems may be located in wetland buffers on a case-by-case basis if deemed necessary and approved by the public works and planning departments.

2. Full dispersion of flow, as defined in Chapter 15.42 BMC (Stormwater Management), may be allowed in a wetland buffer if approved by the public works and planning departments.

3. The above facilities or methods are allowed only if impacts to the buffer, resulting from their installation, are avoided or mitigated.

I. Wetland hydrology shall not be adversely affected by stormwater management. Post-development wetland hydrology shall match pre-development wetland hydrology to the maximum extent feasible. An annual evaluation of hydrologic conditions, conducted by a qualified wetland professional or hydrologist, may be required to document hydrologic conditions.

J. Preference of Mitigation Actions. Mitigation actions shall occur in the following order of preference after mitigation sequencing as specified in BMC 22.08.020, Mitigation sequencing, has been applied:

1. Restoring wetlands on upland sites that were formally wetlands.

2. Creating wetlands on disturbed upland sites such as those with vegetative cover consisting primarily of non-native introduced species. This should only be attempted when there is a consistent source of hydrology and it can be shown that the surface and subsurface hydrologic regime is conducive for the wetland community that is being designed.

3. Enhancing significantly degraded wetlands in combination with restoration or creation. Such enhancement should be part of a mitigation package that includes replacing the impacted area to meet appropriate ratio requirements.

K. Specific Types of Mitigation. The following types of mitigation are fully defined in Chapter 22.10 BMC. In the interest of consistency, they are the definitions provided by the Army Corps of Engineers in its “Regulatory Guidance Letter 02-02.” They have also been adopted by the Washington State Department of Ecology. For the purposes of this chapter, the mitigation categories are:

1. Restoration. This includes re-establishment or rehabilitation.

2. Creation.

3. Enhancement. Unlike restoration activities, enhancement results in a change of wetland functions, not a net gain of function or wetland acres.

4. Preservation. Preservation in combination with other forms of mitigation is allowed. Preservation as the sole means of mitigation for wetland impacts may be allowed if the wetland area to be preserved meets all of the following criteria:

a. The preserved wetland and buffer are protected in perpetuity through a conservation easement, deed restriction, or dedication as a separate tract;

b. The area proposed for preservation is of high quality (scores between 51 and 100 points in the wetland rating system), is located in the same watershed, and is critical to the health of the watershed or sub-basin. Some of the other high quality features include:

i. Rare wetland types such as bogs, mature forested wetlands, estuaries, or vital wildlife habitat;

ii. High regional or watershed importance;

iii. Large size with high species diversity (plants and/or animals) and a high abundance;

c. Preservation is used as a form of compensation only after mitigation sequencing specified in BMC 22.08.020, Mitigation sequencing, has been applied;

d. Creation, restoration, and enhancement opportunities have also been considered and preservation is the best mitigation option;

e. Preservation sites include buffer areas adequate to protect the habitat and its functions from encroachment and degradation;

f. The impacts are to a Category II, III, or IV wetland;

g. The preservation site is determined to be under imminent threat, specifically sites with the potential to experience a high rate of undesirable ecological change due to on- and/or off-site activities;

h. Replacement ratios are listed in Table 4. Replacement ratios for preservation used in combination with other forms of mitigation are to be determined by the director.

L. Location. Site selection for compensatory mitigation shall be based on a location that will provide the greatest ecological benefit and have the greatest likelihood of success. Where feasible, mitigation shall occur in the same sub-basin as the permitted wetland alteration. However, if it can be demonstrated that a mitigation site in an alternative sub-basin or watershed would provide a greater ecological benefit and offer a more successful replacement of wetland functions and values, compensatory mitigation can take place in an alternative sub-basin or watershed.

M. Mitigation Banking. Mitigation banking is encouraged if it provides a greater ecological benefit and provides a more successful replacement of wetland functions and values. This chapter does not expressly regulate mitigation banking; state guidelines for mitigation banking should be adhered to.

N. Mitigation Ratios. The following ratios appearing in Table 4 and consideration of factors described in this section shall be used to determine the relative amount of created, restored, or enhanced wetlands that will be required to replace impacted wetlands. The first number refers to the amount of wetland area providing mitigation and the second refers to the amount of wetland area impacted or altered.

Wetland Replacement Ratios
Table 4	Creation	Restoration (Rehabilitation)	Enhancement	Preservation
Category I BMC 16.55.280(A)(4) Mature forested wetland or BMC 16.55.280(A)(6) scores 70 points or more in wetland rating	6:1	8:1	24:1	N/A
Category I BMC 16.55.280(A) all others	Case-by-case basis; may not be possible	Case-by-case basis; may not be possible	Case-by-case basis; may not be possible	N/A
Category II	3:1	4:1	8:1	16:1
Category III	2:1	3:1	6:1	10:1 Case-by-case basis
Category IV	1.5:1	1.5:1	3:1	5:1 to 10:1 Case-by-case basis

1. Provisions for Increasing or Decreasing Ratios. The director may increase or decrease the ratios based on one or more of the following:

a. Replacement ratios may be increased under the following circumstances:

i. Uncertainty exists as to the probable success of the proposed restoration or creation;

ii. A significant period of time will elapse between impact and establishment of wetland functions at the mitigation site;

iii. Proposed compensation will result in a lower category wetland or reduced functions relative to the wetland being impacted; or

iv. The impact was an unauthorized impact.

b. Replacement ratios may be decreased under the following circumstances:

i. The proposed mitigation actions are conducted in advance of the impact and are shown to be successful;

ii. Documentation by the applicant demonstrates that the proposed compensation actions will provide functions and values that are significantly greater than the wetland being impacted; or

iii. Documentation by the applicant provides more certainty that the proposed compensation action will be successful. Documentation could include extensive hydrologic data to support the proposed water regime.

1. Prepared by a Qualified Professional. A wetland mitigation report shall be prepared by a qualified professional as defined in Chapter 22.10 BMC.

a. Detailed summary of the project, including the wetland and buffer impacts and the proposed mitigation, to appear in the beginning of the report;

b. Complete site characterization to include parcel size, soils, vegetation, hydrology, wildlife, and topography;

c. Complete site characterization of the proposed mitigation site to include parcel size, soils, vegetation, hydrology, topography and wildlife;

d. Goals, objectives, and performance standards of the mitigation proposal;

e. Monitoring, maintenance, and contingency plan;

f. Function assessment of wetland to be impacted;

g. Delineation report, with maps, of site to be impacted;

h. Map of development, with scale, overlaid on wetland delineation map; and

i. An estimate for surety for the entire project, including the required number of years of maintenance. [Ord. 2013-02-005 § 2 (Exh. 1)].