20D.140.30 Wetlands.

20D.140.30-010 Classification and Rating of Wetlands.

To promote consistent application of the standards and requirements of this chapter, wetlands within the City of Redmond shall be classified according to their characteristics, function and value, and/or their sensitivity to disturbance. Wetlands shall be rated and regulated according to the categories defined by the Washington State Department of Ecology Wetland Rating System for Western Washington (Ecology Publication No. 04-06-025) as revised. This document contains the methods for determining the wetland category.

(1) Wetland Classification. Wetlands, as defined by this chapter, shall be designated Category I, Category II, Category III, and Category IV.

(a) Category I wetlands are those wetlands that represent a unique or rare wetland type, are more sensitive to disturbance than most wetlands, are relatively undisturbed and contain ecological attributes that are impossible to replace within a human lifetime, or provide a high level of functions. All wetlands with one or more of the following criteria shall be considered a Category I wetland:

(i) Wetlands that are identified by scientists of the Washington Natural Heritage Program/DNE as high quality, relatively undisturbed wetlands, or wetlands that support state listed threatened or endangered plants; or

(ii) Bogs; or

(iii) Mature and old-growth forested wetlands over one acre in size; or

(iv) Wetlands that provide a very high level of functions as evidenced by a score of 70 points or more on the Western Washington Rating System form.

(b) Category II wetlands are those wetlands that provide high levels of some functions which are difficult to replace. Category II wetlands meet the following criteria:

(i) Wetlands scoring between 51 to 69 points on the Western Washington Rating System form; or

(ii) Wetlands that do not meet the criteria of Category I.

(c) Category III wetlands are those wetlands that provide a moderate level of functions. They are typically more disturbed and have less diversity or are more isolated from other natural resources in the landscape. Category III wetlands meet the following criteria:

(i) Wetlands scoring between 30 to 50 points on the Western Washington Rating System form; or

(ii) Wetlands that do not meet the criteria of Category I.

(d) Category IV wetlands are those wetlands that provide the lowest level of function. These wetlands score less than 30 points on the Western Washington Rating System form.

(2) Classification of wetlands shall be determined by the Committee based on consideration of the following factors:

(a) Maps adopted pursuant to this chapter, including the wetland map, which identifies the approximate location and extent of wetlands. This map shall be used as a general guide only for the assistance of property owners and other interested parties; boundaries are generalized. The actual type, extent, and boundaries of wetlands shall be determined in the field by a qualified consultant according to the procedures, definition, and criteria established by this chapter. In the event of any conflict between the critical area location and designation shown on the City’s map and the criteria or standards of this section, the criteria and standards shall prevail;

(b) National Wetlands Inventory Maps prepared by the U.S. Fish and Wildlife Service;

(d) Consideration of the technical reports submitted by qualified consultants in connection with applications subject to these regulations. (Ord. 2259)

20D.140.30-020 Wetland Buffers.

(1) Required buffer widths shall reflect the sensitivity of the particular wetland or the risks associated with development and, in those circumstances permitted by these regulations, the type and intensity of human activity and site design proposed to be conducted on or near the critical area.

(2) Wetland buffers shall be measured from the wetland edge as delineated and marked in the field using the DOE Wetland Manual. Wetland buffers shall be established as follows:


Wetland Category and Characteristics	Buffer Width (feet) by Impact of Land Use* (see below)	Other Measures Recommended for Protection
Category I
Forested	Buffer size to be based on score for habitat functions or water quality functions	If forested wetland scores high for habitat, need to maintain connectivity to other natural areas. Restore degraded parts of buffer.
High level of function for habitat (score for habitat 29 – 36 pts.)	Low: 150 Moderate: 225 High: 300	Maintain connectivity to other natural areas. Restore degraded parts of buffer.
Moderate level of function for habitat (score for habitat 20 – 28 pts.)	Low: 75 Moderate: 110 High: 150	No recommendations at this time.
High level of function for water quality improvement (24 – 32 pts.) and low for habitat (less than 20 pts.)	Low: 50 Moderate: 75 High: 100	No additional discharges of untreated runoff.
Not meeting any of the above criteria	Low: 50 Moderate: 75 High: 100	No recommendations at this time.
Category II
High level of function for habitat (score for habitat 29 – 36 pts.)	Low: 150 Moderate: 225 High: 300	Maintain connectivity to other natural areas.
Moderate level of function for habitat (score for habitat 20 – 28 pts.)	Low: 75 Moderate: 100 High: 150	No recommendations at this time.
High level of function for water quality improvement and low for habitat (score for water quality 24 – 32 pts.; habitat less than 20 pts.)	Low: 50 Moderate: 75 High: 100	No additional discharges of untreated runoff.
Not meeting above criteria	Low: 50 Moderate: 75 High: 100	No recommendations at this time.
Category III
Moderate level of function for habitat (score for habitat 20 – 28 pts.)	Low: 75 Moderate: 110 High: 150	No recommendations at this time.
Not meeting above criteria	Low: 40 Moderate: 60 High: 80	No recommendations at this time.
Category IV
Score for functions less than 30 pts.	Low: 25 Moderate: 40 High: 50	No recommendations at this time.

* Consistent with the Department of Ecology classification system identified above, high, medium and low impact land uses are defined as follows:

(a) High impact land uses include: commercial, industrial, institutional, retail sales, high-intensity recreation (golf courses, ball fields), and residential uses with a density of more than one dwelling unit per acre.

(b) Medium impact land uses include residential uses with a density of one unit per acre or less, moderate-intensity open space (parks), and paved trails.

(c) Low impact land uses include: low-intensity open space (such as passive recreation and natural resources preservation) and unpaved trails.

(3) The buffer for a wetland created, restored, or enhanced as compensation for approved wetland alterations shall be that required for the category of the wetland.

(4) Increased Buffer Widths. The Department may extend the width of the buffer in accordance with the recommendations of a qualified wetland professional and the best available science on a case-by-case basis when a larger buffer is necessary to protect wetland functions and values based on site-specific characteristics.

(5) Reduction of Buffer Widths. The Department may allow the standard wetland buffer width to be reduced in accordance with the best available science on a case-by-case basis when it is determined that a smaller area is adequate to protect the wetland functions and values based on site-specific characteristics.

(a) Reduction in buffer width based on reducing the intensity of impacts from proposed land uses. The buffer widths recommended for land uses with high-intensity impacts to wetlands can be reduced to those widths recommended for moderate-intensity impacts under the following conditions:

(i) For wetlands that score moderate or high for habitat (20 points or more), the width of the buffer around the wetland can be reduced if both of the following criteria are met:

(A) A relatively undisturbed vegetated corridor at least 100 feet wide is protected between the wetlands and any other priority habitats as defined by the Washington State Department of Fish and Wildlife. The corridor must be protected for the entire distance between the wetland and the priority habitat via some type of legal protection such as a conservation easement; and

(B) Measures to minimize the impacts of different land uses on wetlands, such as those developed by the Department of Ecology under BAS, are applied.

(ii) For wetlands that score less than 20 points for habitat, the buffer width can be reduced to that required for moderate land use impacts if measures to minimize the impacts of different land uses on wetlands, such as those developed by the Department of Ecology under BAS, are applied.

(b) Reductions in buffer widths where existing roads or structures lie within the buffer. Where a legally established, nonconforming use of the buffer exists, proposed actions in the buffer may be permitted as long as they do not increase the degree of nonconformity. In terms of wetlands, this means no increase in the impacts to the wetland from activities in the buffer.

(6) Wetland Buffer Width Averaging. Wetland buffer widths may be modified by averaging buffer widths as set forth herein. The Department may allow modification of the standard wetland buffer width in accordance with the best available science on a case-by-case basis by averaging buffer widths. Averaging buffer widths may only be allowed where a qualified wetland professional demonstrates that:

(a) It will not reduce the functions or values;

(b) The wetland contains variations in sensitivity due to existing physical characteristics or the character of the buffer varies in slope, soils, or vegetation, and the wetland would benefit from a wider buffer in places and would not be adversely impacted by a narrower buffer in other places;

(c) The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer; and

(d) The buffer width is not reduced more than 25 percent of the width or 50 feet, whichever is less, except for buffers between Category IV wetlands and low- or moderate-intensity land uses.

(7) Buffer widths may be reduced by buffer width reduction or buffer width averaging as stated above. However, the use of either of these mechanisms or a combination of these mechanisms shall not result in a buffer width less than 75 percent of the standard buffer required as identified in subsection (2) of this section.

(8) Storm water management facilities, such as biofiltration swales and outfalls, may be located within the outer 25 percent of the buffer; provided, that no other location is feasible, and the location of such facilities will not degrade the functions or values of the wetland. Storm water ponds must be located outside of the required buffer. (Ord. 2259)

20D.140.30-030 Alteration of Wetlands.

(1) Wetland alteration shall result in no net loss of wetland area, except where the following criteria are met:

(a) The lost wetland area provides minimal functions and the mitigation action(s) results in a net gain in wetland functions as determined by a site-specific assessment; or

(b) The lost wetland area provided minimal functions as determined by a site-specific functional assessment and other replacement habitats provide greater benefits to the functioning of the watershed, such as riparian habitat restoration and enhancement.

(2) Category I Wetlands. Alterations of Category I wetlands shall be prohibited subject to the reasonable use provisions of this chapter.

(3) Category II, III, and IV Wetlands.

(a) Any proposed alteration and mitigation shall comply with the mitigation performance standards and requirements of these regulations; and

(b) No net loss of wetland function and value may occur.

(c) Where enhancement or replacement is proposed, ratios shall comply with the requirements of subsection (7) of this section.

(4) Mitigation for alterations to wetlands shall achieve equivalent or greater biological functions. Mitigation plans shall be consistent with the Department of Ecology Guidance on Wetland Mitigation in Washington State, Part 2: Guidelines for Developing Freshwater Wetlands Mitigation Plans and Proposals, April, 2004, as revised.

(5) Mitigation actions shall address functions affected by the alteration to achieve functional equivalency or improvement, and shall provide similar wetland functions as those lost except when:

(a) The filled/impacted wetland provides minimal functions as determined by a site-specific function assessment and the proposed mitigation action(s) will provide equal or greater functions or will provide functions shown to be limiting within a watershed through a formal watershed assessment plan or protocol; or

(b) Out-of-kind replacement will best meet formerly identified regional goals, such as replacement of historically diminished wetland types.

(6) Mitigation actions that require compensation by replacing, enhancing, or substitution shall occur in the following order of preference:

(a) Preserving high-quality wetlands that are under imminent threat.

(b) Restoring wetlands on upland sites that were formerly wetlands.

(c) Creating wetlands on disturbed upland sites such as those with vegetative cover consisting primarily of exotic introduced species.

(d) Enhancing significantly degraded wetlands.

(7) Wetland Replacement Ratios.

(a) Where wetland alterations are permitted by the City, the applicant shall restore or create areas of wetlands in order to compensate for wetland losses. Equivalent areas shall be determined according to acreage, function, type, location, timing factors, and projected success of restoration or creation.

(b) When creating or enhancing wetlands, the following acreage replacement ratios shall be used:


Category and Type of Wetland	Creation or Re‑establishment	Rehabilitation (Restoration)	Re‑establishment or Creation (R/C) and Enhancement	Enhancement Only
Category I Forested	6:1	12:1	1:1 R/C and 10:1 E	24:1
Category I based on score	4:1	8:1	1:1 R/C and 6:1 E	16:1
Category II	3:1	8:1	1:1 R/C and 4:1 E	12:1
Category III	2:1	4:1	1:1 R/C and 2:1 E	8:1
Category IV	1.5:1	3:1	1:1 R/C and 2:1 E	6:1

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

(ii) A significant period of time will elapse between impact and replication of wetland functions; or

(iii) Proposed mitigation will result in a lower category wetland or reduced functions relative to the wetland being impacted; or

(iv) The impact was an unauthorized impact.

(d) Decreased Replacement Ratio. The Department may decrease these ratios under the following circumstances:

(i) Documentation by a qualified wetland specialist demonstrates that the proposed mitigation actions have a very high likelihood of success;

(ii) Documentation by a qualified wetland specialist demonstrates that the proposed mitigation actions will provide functions and values that are significantly greater than the wetland being impacted; or

(iii) The proposed mitigation actions are conducted in advance of the impact and have been shown to be successful.

(e) Enhanced and created wetlands shall be appropriately classified and buffered. (Ord. 2259)

20D.140.30-040 Wetlands Performance/Design Standards.

(1) Use plants indigenous to the Pacific Northwest region (not introduced or foreign species);

(2) Use plants adaptable to a broad range of water depths;

(3) Plants should be commercially available or available from local sources;

(4) Plant species high in food and cover value for fish and wildlife must be used;

(5) Avoid committing significant areas of the site to species that have questionable potential for successful establishment;

(6) Plant selection must be approved by a qualified wetland specialist;

(7) Water depth is not to exceed six and one-half feet (two meters);

(8) The grade or slope that water flows through the wetland is not to exceed six percent for wetland creation sites;

(9) Slopes within the wetland basin and the buffer zone may not be steeper than 3:1 (horizontal to vertical) for wetland creation sites;

(10) Substrate should consist of a minimum of one foot, in depth, of clean (uncontaminated with chemicals or solid/hazardous wastes) inorganic/organic materials for wetland creation sites;

(11) Planting densities and placement of plants should be determined by a qualified wetland professional and shown on the design plans;

(12) The planting plan must be approved by the Department;

(13) Confine stockpiling to upland areas and ensure contract specifications limit stockpiling of earthen materials to durations in accordance with City clearing and grading standards, unless otherwise approved by the Committee;

(14) Planting instructions shall be submitted which describe proper placement, diversity, and spacing of seeds, tubers, bulbs, rhizomes, sprigs, plugs, and transplanted stock;

(15) Apply controlled release non-phosphorus fertilizer at the time of planting and afterward only as plant conditions warrant (determined during the monitoring process);

(16) Install an irrigation system, if necessary, for the initial establishment period;

(17) Construction specifications and methods must be approved by a qualified consultant and the Department; and

(18) Construction management should occur by a qualified consultant and be inspected by the City. (Ord. 2259)