Mukilteo City Zoning Code
CHAPTER 17
52B WETLAND REGULATIONS
§ 17.52B.010 Purpose.
The purpose of this chapter is to protect the functions and values of wetlands, including but not limited to:
A.
Maintaining water quality.
B.
Storing and conveying stormwater and floodwater.
C.
Recharging ground water.
D.
Providing important fish and wildlife habitat.
E.
Serving as areas for recreation, education, and aesthetic appreciation.
(Ord. 1533, 3/23/2026)
§ 17.52B.020 Applicability.
A.
General. This chapter applies to any new activity within 50 feet of a wetland or its buffer, unless specifically exempted in Chapter 17.52.
B.
Limited applicability to existing development. Enhancement of wetlands or buffers degraded by development legally established before the adoption of these regulations is not required. Development and activities existing prior to the adoption of the ordinance codified in this chapter may continue. Legally established impervious areas may be redeveloped without mitigation as long as the total square footage and location of impervious surface remains unchanged.
C.
Relationship to Fish and Wildlife Habitat Conservation Areas. Wetlands are also considered Fish and Wildlife Habitat Conservation Areas and subject to the regulations in Chapter 17.52C.
(Ord. 1533, 3/23/2026)
§ 17.52B.030 Required reports, plans, and sureties.
A.
Adherence to the recommendations required. All recommendations in required reports are considered conditions of approval. Failure to follow report recommendations will be considered a violation of permit conditions.
B.
Wetland delineation and buffer analysis report.
1.
Required. When proposed development is within 50 feet of a wetland or its buffer, the applicant must submit a wetland delineation report prepared by a qualified professional in accordance with city requirements and best available science.
2.
Contents. The report must:
a.
Identify the wetland classification based on the most current Washington State Department of Ecology wetland rating guidance.
b.
Provide sufficient information for the city to establish the location and boundaries of both the wetland and its associated buffer. At a minimum, this must include field worksheets, map of test pit locations, and clear findings.
c.
Analyze existing conditions and the city's standard buffers to determine if the standard buffer width is adequate to ensure no net loss of functions or if vegetation enhancements or expanded buffers are needed.
3.
Expiration. Wetland delineation reports are valid for five years. Reports older than five years at the time of permit submittal must be updated.
4.
Relationship to biological/habitat assessment report. Wetlands are also considered fish and wildlife habitat conservation areas. Required wetland and biological/habitat delineations and assessments may be combined.
C.
Mitigation plan.
1.
Required. When a non-exempt development activity is located within a wetland or its buffer, the applicant must submit a mitigation plan prepared by a qualified professional.
2.
Contents. All mitigation plans must include:
a.
Summary of the plan preparer's relevant experience and qualifications.
b.
Project summary and drawings describing general project layout, construction timing sequencing, and grading and clearing limits.
c.
Analysis of site characteristics and wetland/buffer functions as well as a description of expected impacts.
d.
Proposed mitigation measures to ensure no net loss together with analysis of how mitigation sequencing was applied and documentation of best available science supporting the proposed mitigation.
e.
Planting details, including species, quantities, locations, size, spacing, and density as well as plat protection and maintenance provisions to preserve existing vegetation.
f.
Summary of required permits. A list of all required permits, including federal and state approvals.
g.
Performance standards. The plan must identify measurable criteria to evaluate success of the mitigation and compliance with this chapter.
h.
Provisions to ensure a qualified professional is on site during construction to ensure mitigation is installed in accordance with the approved plan and that a final report documenting mitigation completion is submitted to the city.
i.
Contingency plan. The plan must identify corrective actions to be taken if monitoring shows performance standards are not being met.
D.
Monitoring program.
1.
Required. When a non-exempt development activity is located within a wetland or its buffer, a monitoring program is required.
2.
Contents. The monitoring program must ensure the site is monitored for an adequate number of years to ensure performance standards in mitigation plan are met (minimum of five years for buffer impacts, minimum of 10 years for wetland impacts).
3.
Annual reports. Annual monitoring reports consistent with best available science and Ecology guidance must be submitted to the city.
4.
Extended monitoring. If the site does not perform as expected, the city may extend monitoring in two-year increments until performance standards are met.
E.
Sureties and fees. To ensure compliance with mitigation and monitoring requirements, the city may require:
1.
Performance surety. Mitigation must be completed before final project approval or Certificate of Occupancy. If weather prevents timely completion, a performance surety equal to 150% of the mitigation installation costs may be accepted, conditioned on work being completed within six months.
2.
Maintenance surety. A 10-year maintenance surety equal to 15% of the mitigation installation cost is required for all mitigation projects.
3.
Monitoring deposit. The city may charge a set fee to cover the city's costs to review the yearly monitoring reports and conduct site inspections to ensure the performance standards are met.
F.
Third-party review. The city may retain a qualified professional, at the applicant's expense, to review and confirm any findings in required delineations, reports, studies, or plans.
(Ord. 1533, 3/23/2026)
§ 17.52B.050 Development outside wetlands and their buffers.
All new development within 50 feet of a wetland buffer must:
A.
Temporary protections. Put temporary, protective measures in place during construction to ensure that dust, debris, and runoff do not enter the wetland.
B.
Permanent protections. When a wetland or its buffer exists on a property, the applicant must record notice of wetland presence with the Snohomish County assessor's office in the form of an easement, land use binder, or separate plat tract held in common ownership. The document must identify the approximate location of the wetland and restrict the use of herbicides, pesticides, and similar contaminants within a wetland or its buffer.
(Ord. 1533, 3/23/2026)
§ 17.52B.060 Development inside wetland buffers.
A.
Buffer widths. Buffer widths vary based on the category of wetland and the intensity of the proposed development. Land use impact categories are defined in Chapter 17.08.
Minimum Buffer Widths | |||
|---|---|---|---|
Wetland Category | Land Use Impact | ||
Low | Moderate | High | |
Category I | 150 feet | 225 feet | 300 feet |
Category II | 150 feet | 225 feet | 300 feet |
Category III | 75 feet | 110 feet | 150 feet |
Category IV | 25 feet | 40 feet | 50 feet |
B.
Development standards.
1.
General. Except as specified below or allowed through reasonable use approval, wetland buffers must be retained in an undisturbed condition.
2.
Authorized activities. The following uses are allowed in the outer 25% of a buffer if they do not reduce wetland functions:
a.
Viewing platforms and interpretive signage.
b.
Pervious surface or boardwalk trails no more than five feet wide that are routed to avoid trees with 18 inches or larger diameter at breast height (DBH).
C.
Mitigation. Any impacts to wetland buffers must be mitigated at a one-to-one ratio to restore and preserve original functions.
(Ord. 1533, 3/23/2026)
§ 17.52B.070 Development inside wetlands.
A.
Reasonable use required to alter. No alterations to wetlands or their buffers for non-exempt activities is allowed without reasonable use approval.
B.
Compensatory mitigation. All wetland and buffer impacts must be mitigated using the mitigation sequencing options in Chapter 17.52. Where impacts cannot be avoided or minimized, compensatory mitigation may be used.
1.
Mitigation ratios for temporary impacts. When a project causes temporary impacts that can be restored to pre-disturbance conditions within a single growing season, the mitigation ratio is 1:1. All other impacts must comply with the permanent impact ratios.
2.
Mitigation ratios for permanent impacts. All permanent wetland impacts must be mitigated at the ratios below. These ratios apply to in-kind, on-site creation or restoration of the same wetland category.
Permanent Impact Mitigation Ratios Based on Method | |||
|---|---|---|---|
Impacted Wetland | Create/Re-establish | Rehabilitate | Enhance/Preserve |
Category I | 4:1 | 8:1 | 16:1 |
Category II | 3:1 | 6:1 | 12:1 |
Category III | 2:1 | 4:1 | 8:1 |
Category IV | 1.5:1 | 3:1 | 6:1 |
3.
Mitigation ratios for wetlands with special characteristics. Impacts to the following wetlands with special characteristics require consultation with the Department of Ecology and Department of Natural Resources to determine mitigation ratios:
a.
Category I forested;
b.
Bogs;
c.
Wetlands of high conservation value;
d.
Category I and II estuarine wetlands;
e.
Interdunal wetlands;
f.
Category I and II wetlands in coastal lagoons.
4.
Methods. Mitigation for wetland and buffer impacts must rely on a method below, which are listed in order of preference. A lower-preference form of mitigation should be used only if a qualified professional demonstrates to the director's satisfaction that all higher-ranked methods of mitigation are not viable.
a.
Re-establish. Manipulate the physical, chemical, or biological characteristics of a site to return natural/historic functions and environmental processes to a former wetland.
b.
Rehabilitate. Manipulate the physical, chemical, or biological characteristics of a site to repair natural/historic functions and environmental processes to a degraded wetland.
c.
Create. Manipulate the physical, chemical, or biological characteristics of a site to develop a wetland on an upland where a wetland did not previously exist at an upland site.
d.
Preservation. The removal of a threat to, or preventing the decline of, wetlands by an action in or near those wetlands.
e.
Enhance. Manipulate the physical, chemical, or biological characteristics of a wetland to heighten, intensify, or improve specific wetland function(s).
5.
Tools. Any of the following approaches may be used to provide compensatory mitigation:
a.
Wetland mitigation bank. Credits from a wetland mitigation bank certified through Chapter 173-700 WAC may be used to compensate for impacts when the project is within the service area of the bank and the proposed use of credits is consistent with both the replacement ratios of the city code and the terms and conditions of the bank's certification.
b.
Permittee-responsible mitigation. On- or off-site mitigation funded and executed by the permittee may be used after a qualified professional demonstrates to the director's satisfaction that the mitigation would provide appropriate compensation for the proposed impacts. Mitigation sites should be in the same sub-drainage basin unless the applicant can demonstrate that a mitigation site in a different sub-drainage basin is ecologically preferable.
6.
Mitigation timing. Compensatory mitigation projects must be completed prior to use or occupancy.
(Ord. 1533, 3/23/2026)
