16.18B.040 Wetland buffers | Algona Municipal Code

16.18B.040 Wetland buffers.

A. Buffer Requirements. The standard buffer widths in Table 16.18B.040.1 have been established in accordance with the best available science. They are based on the category of wetland and the habitat score as determined by a qualified wetland professional using the most current version of the Washington State Wetland Rating System for Western Washington.

1. The use of the standard buffer widths requires the implementation of the measures, where possible, in Table 16.18B.040.2, where applicable, to minimize the impacts of the adjacent land uses.

2. If an applicant chooses not to apply the mitigation measures in Table 16.18B.040.2, then a thirty-three percent increase in the width of all buffers is required. For example, a seventy-five-foot buffer with the measures to minimize impact would be a one-hundred-foot buffer without them.

3. The standard buffer widths assume that the buffer is vegetated with a native plant community appropriate for the ecoregion. If the existing buffer is unvegetated, sparsely vegetated, or vegetated with invasive species that do not perform needed functions, the buffer should either be planted to create the appropriate plant community, or the buffer should be widened to ensure that adequate functions of the buffer are provided.

Table 16.18B.040.1. Wetland Buffer Requirements for Western Washington
Wetland Category	Buffer width if wetland scores 3 – 4 habitat points	Additional buffer width if wetland scores 5 habitat points	Additional buffer width if wetland scores 6 – 7 habitat points	Additional buffer width if wetland scores 8 – 9 habitat points
Category I: Based on total score	75 ft	Add 30 ft	Add 90 ft	Add 150 ft
Category I: Bogs and wetlands of high conservation value	190 ft			Add 35 ft
Category I: Forested	75 ft	Add 30 ft	Add 90 ft	Add 150 ft
Category II: Based on score	75 ft	Add 30 ft	Add 90 ft	Add 150 ft
Category III: (all)	60 ft	Add 45 ft	Add 105 ft	Add 165 ft
Category IV: (all)	40 ft.

4. Additional buffer widths are added to the standard buffer widths. For example, a Category I wetland scoring eight to nine points for habitat function would require a buffer of two hundred twenty-five feet (seventy-five plus one hundred fifty).

Table 16.18B.040.2. Required Measures To Minimize Impacts to Wetlands

(Measures are required, where applicable to a specific proposal.)
Type of Disturbance	Required Measures to Minimize Impact
Lights	• Direct lights down and away from the wetland
Noise	• Orient noise-generating activities away from wetland edge
Toxic runoff	• Route all new, untreated runoff away from wetland while ensuring wetland is not dewatered • Establish covenants limiting use of pesticides and herbicides within 150 feet of wetland buffer
Storm water runoff	• Retrofit storm water detention and treatment for roads and existing adjacent development • Prevent channelized flow from lawns that directly enters the buffer
Change in water regime	• Apply appropriate stormwater management to infiltrate, treat, detain, and disperse runoff appropriately and only into outer edge of buffer, if allowed
Pets and Human Activity	• Use privacy fencing or plant dense native vegetation to delineate buffer edge and to discourage entry into buffer by humans and pets • Place wetland and buffer in a NGPA or tract
Dust	• Use best management practices to control dust
Disruption of corridors or connections	• Maintain connections to off-site areas that are undisturbed • Restore corridors or connections to off-site habitats by replanting

5. Increased Wetland Buffer Area Width. Buffer widths shall be increased on a case-by-case basis as determined by the mayor or designee when a larger buffer is necessary to protect wetland functions and values. This determination shall be supported by appropriate documentation showing that it is reasonably related to protection of the functions and values of the wetland. The documentation must include but not be limited to the following criteria:

a. The wetland is used by a plant or animal species listed by the federal government or the state as endangered, threatened, candidate, sensitive, monitored or documented priority species or habitats, or essential or outstanding habitat for those species or has unusual nesting or resting sites such as heron rookeries or raptor nesting trees; or

b. The adjacent land is susceptible to severe erosion, and erosion-control measures will not effectively prevent adverse wetland impacts; or

c. The adjacent land has minimal vegetative cover or slopes greater than thirty percent.

6. Buffer averaging to improve wetland protection may be permitted when all of the following conditions are met:

a. The wetland has significant differences in characteristics that affect its habitat functions, such as a wetland with a forested component adjacent to a degraded emergent component or a “dual-rated” wetland with a Category I area adjacent to a lower-rated area.

b. 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 as demonstrated by a critical areas report from a qualified wetland professional.

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

d. The buffer at its narrowest point is never less than either three-quarters of the required width or seventy-five feet for Category I and II, fifty feet for Category III, and twenty-five feet for Category IV, whichever is greater.

B. Measurement of Wetland Buffers. All buffers shall be measured perpendicular from the wetland boundary as surveyed in the field. The buffer for a wetland created, restored, or enhanced as compensation for approved wetland alterations shall be the same as the buffer required for the target category of the created, restored, or enhanced wetland. Only fully vegetated buffers will be considered. Existing lawns, walkways, driveways, and other mowed or paved areas will not be considered to be buffers or included in buffer area calculations.

C. Buffers on Mitigation Sites. All mitigation sites shall have buffers consistent with the buffer requirements of this chapter. Buffers shall be based on the expected or target category of the proposed wetland mitigation site.

D. Buffer Maintenance. Except as otherwise specified or allowed in accordance with this chapter, wetland buffers shall be retained in an undisturbed or enhanced condition. In the case of compensatory mitigation sites, removal of invasive nonnative weeds is required for the duration of the mitigation bond (Section 16.18A.410).

E. Impacts to Buffers. Requirements for the compensation for impacts to buffers are outlined in Section 16.18A.260.

F. Overlapping Critical Area Buffers. If buffers for two contiguous critical areas overlap (such as buffers for a stream and a wetland), the wider buffer applies.

G. Allowed Buffer Uses. The following uses may be allowed within a wetland buffer in accordance with the review procedures of this chapter, provided they are not prohibited by any other applicable law and they are conducted in a manner so as to minimize impacts to the buffer and adjacent wetland:

1. Conservation and Restoration Activities. Conservation or restoration activities aimed at protecting the soil, water, vegetation, or wildlife.

2. Passive Recreation. Passive recreation facilities designed and in accordance with an approved critical area report, including:

a. Walkways and trails; provided, that those pathways are limited to minor crossings having no adverse impact on water quality. They should be generally parallel to the perimeter of the wetland, located only in the outer twenty-five percent of the wetland buffer area, and located to avoid removal of significant trees. They should be limited to pervious surfaces no more than five feet in width for pedestrian use only. Raised boardwalks utilizing nontreated pilings may be acceptable.

b. Wildlife-viewing structures.

3. Educational and scientific research activities.

4. Normal and routine maintenance and repair of any existing public or private facilities within an existing right-of-way; provided, that the maintenance or repair does not increase the footprint or use of the facility or right-of-way.

5. The harvesting of wild crops in a manner that is not injurious to natural reproduction of such crops and provided the harvesting does not require tilling of soil, planting of crops, chemical applications, or alteration of the wetland by changing existing topography, water conditions, or water sources.

6. Drilling for utilities/utility corridors under a buffer, with entrance/exit portals located completely outside of the wetland buffer boundary; provided, that the drilling does not interrupt the ground water connection to the wetland or percolation of surface water down through the soil column. Specific studies by a hydrologist are required to determine whether the ground water connection to the wetland or percolation of surface water down through the soil column is disturbed.

7. Enhancement of a wetland buffer through the removal of nonnative invasive plant species. Removal of invasive plant species shall be restricted to hand removal. All removed plant material shall be taken away from the site and appropriately disposed of. Plants that appear on the Washington State Noxious Weed Control Board list of noxious weeds must be handled and disposed of according to a noxious weed control plan appropriate to that species. Revegetation with appropriate native species at natural densities is allowed in conjunction with removal of invasive plant species.

8. Storm Water Management Facilities. Storm water management facilities are limited to storm water dispersion outfalls and bioswales. They may be allowed within the outer twenty-five percent of the buffer of Category III or IV wetlands only; provided, that:

a. No other location is feasible; and

b. The location of such facilities will not degrade the functions or values of the wetland; and

c. Storm water management facilities are not allowed in buffers of Category I or II wetlands.

9. Nonconforming Uses. Repair and maintenance of nonconforming uses or structures, where legally established within the buffer, provided they do not increase the degree of nonconformity.

1. Temporary Markers. The outer perimeter of the wetland buffer and the clearing limits identified by an approved permit or authorization shall be marked in the field with temporary “clearing limits” fencing in such a way as to ensure that no unauthorized intrusion will occur. The marking is subject to inspection by the mayor or designee prior to the commencement of permitted activities. This temporary marking shall be maintained throughout construction and shall not be removed until permanent signs, if required, are in place.

2. Permanent Signs. As a condition of any permit or authorization issued pursuant to this chapter, the mayor or designee may require the applicant to install permanent signs along the boundary of a wetland or buffer.

a. Permanent signs shall be made of an enamel-coated metal face and attached to a metal post or another nontreated material of equal durability. Signs must be posted at an interval of one per lot or every fifty feet, whichever is less, and must be maintained by the property owner in perpetuity. The signs shall be worded as follows or with alternative language approved by the mayor or designee:

Protected Wetland Area

Do Not Disturb

Contact City of Algona at 253-833-2897

Regarding Uses, Restrictions, and

Opportunities for Stewardship

b. The provisions of subsection (H)(2)(a) of this section may be modified as necessary to assure protection of sensitive features or wildlife.

a. The applicant shall be required to install a permanent fence around the wetland or buffer when domestic grazing animals are present or may be introduced on site.

b. Fencing installed as part of a proposed activity or as required in this subsection shall be designed so as to not interfere with species migration, including fish runs, and shall be constructed in a manner that minimizes impacts to the wetland and associated habitat. (Ord. 1104-15 § 1 (Att. A)).