City of Spokane

Spokane Municipal Code

Title 17E
Chapter 17E.070
Section 17E.070.110

Title 17E Environmental Standards

Chapter 17E.070 Wetlands Protection

Section 17E.070.110 Wetland Buffers
  1. Standard Buffer Zone Widths.
    Wetland buffer zones shall be required for all regulated activities adjacent to wetlands.  Any wetland created, restored, or enhanced as compensation for approved wetland alterations shall also include the standard buffer required for the category of the created, restored, or enhanced wetland.  All buffers shall be measured from the wetland boundary as surveyed in the field pursuant to the requirements of SMC 17E.070.030.  The width of the wetland buffer zone shall be determined according to the rating assigned to the wetland in accordance with SMC 17E.070.100 and consistent with Wetlands in Washington State, Volume 2, Protecting and Managing Wetlands, Guidance on Buffers and Ratios (Appendix 8-D) as revised, for wetland category, intensity of impacts, wetland functions, habitat scores, or special characteristics.  Standard buffer widths will be determined based on an evaluation of the following:

    1. conditions of the wetland;

    2. conditions of the buffer;

    3. proposed land uses adjacent to the buffer; and

    4. the functions intended to be protected.

  2. Wildlife habitat function is the most susceptible to developmental change and requires the greatest buffer protection.  Protection of wildlife habitat functions require twenty five to seventy five feet for wetlands with minimal habitat functions and low intensity land uses adjacent to the wetlands, fifty to two hundred feet for wetlands with moderate habitat function and moderate or high intensity land use adjacent to the wetlands, and one hundred fifty to two hundred fifty plus feet for wetlands with high habitat functions depending on the intensity of the adjacent land use.  The width of the wetland buffer zone shall be determined from one of the following two alternatives:

    1. Alternative 1.
      Unless SMC 17E.070.110(3) (Table 17E.070.110-4) applies, width based solely on wetland category as follows:

Table 17E.070.110-1

Wetland Category

Buffer Width

Type I

250 ft

Type II

200 ft

Type III

150 ft

Type IV

50 ft

  1. Alternative 2.
    Alternative 2 provides three buffer widths based on habitat scores. Habitat score refers to the quality of physical structures such as vegetation, open water, and connections to other wildlife habitats that are necessary for a wide range of species, including birds, mammals, and amphibians. Where more than one width applies based on score for function or based on special characteristics, the calculation providing the widest buffer shall be used. Widths are based on wetland category, intensity of impacts from proposed changes in land use, and wetland functions or special characteristics. Land use intensity shall be determined as follows:

Table 17E.070.110-2. Types of proposed land use that can result in high, moderate, and low levels of impacts to adjacent wetlands.

Impact from Proposed Change in Land Use

Types of Land Use Based on Common Zoning Designations


Commercial, Industrial and Institutional
Residential (more than 1 unit/acre)
High-intensity recreation (golf courses, ball fields, etc.)
Conversion to high intensity agricultural (dairies, nurseries, greenhouses, etc.)
Hobby Farms


Residential (1 unit/acre or less)
Moderate-intensity active open space (parks with biking, jogging, etc.)
Conversion to moderate intensity agriculture (orchards, hay fields, etc.)
Paved trails
Building of logging roads
Utility corridor with access/maintenance road
Forestry (cutting of trees only)


Passive open space (hiking, bird-watching, etc.)
Unpaved trails
Utility corridor without road or vegetation management.

Table 17 E.070.110-3

Category of Wetland

Land Use with Low Impact

Land Use with Moderate Impact

Land Use with High Impact


125 ft.

190 ft.

250 ft.


100 ft.

150 ft.

200 ft.


75 ft.

110 ft.

150 ft.


25 ft.

40 ft.

50 ft.

  1. If a Type I wetland is classified with at least one of the following special characteristics the following buffer table shall apply:

Table 17E.070.110-4

Wetland Characteristics

Buffer Widths by Impact of Proposed Land Use (apply most protective if more than one criterion is met)

Other Measures Recommended for Protection

Wetlands of High Conservation Value

Low - 125 ft
Moderate – 190 ft
High – 250 ft

No additional surface discharges to wetland or its tributaries
No septic systems within 300 ft
Restore degraded parts of buffer


Low - 125 ft
Moderate – 190 ft
High – 250 ft

No additional surface discharges to wetland or its tributaries
Restore degraded parts of buffer


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


Low – 100 ft
Moderate – 150 ft
High – 200 ft

No additional surface discharges to wetland or its tributaries
Restore degraded parts of buffer

High level of function for habitat (score for habitat 8 – 9 points)

Low – 100 ft
Moderate – 150 ft
High – 200 ft

Maintain connections to other habitat areas
Restore degraded parts of buffer

Moderate level of function for habitat (score for habitat 5 - 7 points)

Low – 75 ft
Moderate – 110 ft
High – 150 ft

No recommendations at this time

High level of function for water quality improvement (8 - 9 points) and low for habitat (less than 5 points)

Low – 50 ft
Moderate – 75 ft
High – 100 ft

No additional surface discharges of untreated runoff

Not meeting any of the above characteristics

Low – 50 ft
Moderate – 75 ft
High – 100 ft

No recommendations at this time

  1. Increased Wetland Buffer Zone Width.
    The City may require increased buffer zone widths on a case-by-case basis as determined by the director 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:

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

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

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

  2. Reduction of Standard Wetland Buffer Zone Width.
    The City may reduce the standard wetland buffer zone width on a case-by-case basis as determined by the director, consistent with Wetlands in Washington State, Volume 2, Protecting and Managing Wetlands, Guidance on Buffers and Ratios (Appendix 8-D) as revised, or wetlands that score:

    1. Moderate or high for habitat (five points or more for the habitat functions) the width of the buffer can be reduced if the following criteria are met:

      1. A relatively undisturbed vegetative corridor of at least one hundred feet in width is protected between the wetland and any other priority habitats; and

      2. The protected area is preserved by means of easement, covenant, or other measure;

      3. Measures identified in SMC 17E.070.110(C)(2) (Table 17E.070.110-5) are taken to minimize the impact of any proposed land use or activity

    2. Less than five points for habitat, the buffer width can be reduced to that required for moderate land-use impacts by applying the following measures to minimize the impacts of the proposed land uses or activities:

Table 17E.070.110-5

Examples of Measures used to Minimize Impacts


Direct lights away from wetland


Locate activity that generates noise away from wetland

Toxic runoff

Route all new untreated runoff away from wetland while ensuring wetland is not dewatered, establish covenants limiting use of pesticides within 150’, may apply integrated pest management

Stormwater runoff

Retrofit stormwater detention and treatment for roads and existing adjacent development, prevent channelized flow from lawns that directly enters buffer

Change in water regime

Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surfaces and new lawns

Pets and human disturbance

Use privacy fencing; plant dense vegetation to delineate buffer edge and to discourage disturbance using vegetation appropriate for the ecoregion; place wetland and its buffer in a separate tract


Use best management practices to control dust

  1. Standard Buffer Width Averaging.
    Wetlands may contain significant variations in sensitivity due to existing physical characteristics that may justify buffer width averaging. Standard wetland buffer zones may be modified by averaging buffer widths or a combination of averaging and reduction. Wetland buffer width averaging shall be allowed only where the applicant demonstrates all of the following:

    1. Averaging will provide the necessary biological, chemical and physical support necessary to protect the wetland in question, taking into account the type, intensity, scale and location of the proposed land use;

    2. The land uses causing the least disturbance would be located adjacent to areas where buffer width is reduced and that such land uses are guaranteed in perpetuity by covenant, deed restriction, easement, or other legally binding mechanism;

    3. The total area contained within the wetland buffer after averaging is not less than that contained with the standard buffer prior to averaging. In no instance shall the buffer width be reduced by more than fifty percent of the standard buffer or be less than twenty-five feet.

  2. Wetland Buffer Maintenance.
    Except as otherwise specified wetland buffer zones shall be retained in their natural condition and free from mowing or other cutting activity, except for the removal of noxious weeds. Where buffer disturbances have occurred before or during construction, revegetation with native vegetation shall be required.

  3. Permitted Uses in a Wetland Buffer Zone.
    Regulated activities shall not be allowed in a buffer zone except for the following:

    1. Activities having minimal adverse impacts on buffers and no adverse impacts on wetlands. These may include low-intensity, passive recreational activities such as trails, non-permanent wildlife watching blinds, short-term scientific or education activities, and sport fishing or hunting.  Pervious pedestrian trails may be allowed in a wetland for minor crossings only and with minimal impacts.  Trails may be allowed in the outer twenty five percent of a wetland buffers and should be designed to avoid removal of significant trees.  Such trails are limited to no more than five feet in width.

    2. Storm water management facilities, including biofiltration swales, designed according to the City of Spokane Stormwater Management Manual as revised, and chapter 17D.060 SMC Stormwater Facilities, if no reasonable alternative on-site location is available within the meaning of subsection SMC 17E.070.130, and if sited and designed so that the buffer zone as a whole provides the necessary biological, chemical and physical protection to the wetland in question, taking into account the scale and intensity of the proposed land use. Biofiltration swales will take into account the scale and intensity of the proposed land use, be located in the outer twenty five percent of a Category III or IV wetland buffer provided that no other location is feasible, and will not degrade the functions and values of the wetland or its buffer.]

  4. Structural Setbacks from Buffers.
    Unless otherwise provided, buildings and other accessory structures shall be set back a distance of ten feet from the edges of all delineated critical area buffers protecting fish and wildlife habitat conservation and wetland protection areas. The director may reduce the structural setback limit by up to five feet if construction, operation, and maintenance of the building do not create a risk of negative impacts on the adjacent buffer area. Approval of a reduction of the structural setback from the buffer line shall be provided in writing by the director. The following uses may be allowed in the structural setback area:

    1. Landscaping;

    2. Uncovered decks;

    3. Roof eaves and overhangs, maximum of twenty-four inches;

    4. Pervious unroofed stairways and steps;

    5. Impervious ground surfaces, such as driveways and patios.

Date Passed: Monday, June 19, 2017

Effective Date: Sunday, July 30, 2017

ORD C35508 Section 10