HomeMy WebLinkAboutStaff Report_D-235_Critical Areas Ordinance_v1CITY OF RENTON
Community and Economic Development Department
#D-235: Critical Areas Ordinance
Staff: Mariah Kerrihard, Associate Planner
Date: September 3, 2025
Applicant or Requestor: Staff
_____________________________________________________________________________________
GENERAL DESCRIPTION
The critical areas ordinance (CAO) is a set of development regulations that cities and counties
must adopt and enforce to protect specific environmentally sensitive areas and to safeguard the
public from natural hazards. The CAO is mandated by the state’s Growth Management Act (GMA).
The purpose of the proposed code amendment is to align the City’s regulations with current state
law and “best available science” (BAS) by the end of the year deadline.
BACKGROUND – CRITICAL AREA ORDINANCE
The Critical Areas Regulations are intended to guide development in ways that protect the
environment, public safety, and community well-being. Its goals include preserving natural
habitats, maintaining species diversity, and restoring critical areas where possible, while ensuring
activities in sensitive areas do not cause hazards, damage, or unnecessary costs to the public. It
supports state and city policies, helps officials make informed decisions on development
proposals, and works to minimize risks from issues like flooding and abandoned coal mines. In
doing so, it protects both property and the local tax base while also safeguarding riparian areas—
streams, rivers, and their banks—that provide essential benefits such as clean water, flood
storage, erosion control, and healthy ecosystems for fish and wildlife.
As part of the current update to the Critical Areas Ordinance, three main categories of changes are
being introduced: (1) code cleanup to clarify regulatory language and references, (2) new Channel
Migration Zone (CMZ) regulations and expanded mapping, and (3) updated requirements for
wetlands protection. Wetlands are one of the five types of critical areas identified in the GMA. The
GMA requires specific protections for wetlands because they provide a wide variety of essential
environmental benefits. Without protection or mitigation, even minor disturbances to wetlands can
reduce or eliminate these benefits. The Department of Ecology provides Wetland Guidance for
Critical Areas Ordinance (CAO) updates for Western and Eastern Washington. Their publication is
informed by their earlier best available science (BAS) document, Wetlands in Washington State –
Volume 1: A Synthesis of the Science (Sheldon et al., 2005) and stems from the guidance in
Wetlands in Washington State, Volume 2: Guidance for Protecting and Managing Wetlands
(Granger et al., 2005). The guidance is a concise and current representation of the many strategies
and approaches for managing wetlands found in those earlier volumes. The guidance is for local
jurisdictions working on designating and protecting wetlands as critical areas under the
Washington State Growth Management Act (GMA). At this time, the Channel Migration Zone (CMZ)
is currently within the Shoreline Management Program regulations. We plan to locate it in the CAO,
which provides guidelines for how people can challenge the boundaries of the CMZ, such as, bank
stabilization along the Cedar River. The City is required to adopt the updated regulations by the end
of 2025.
Comparison of Existing vs. Proposed Wetland Buffer Width Changes
Wetland
Category
Habitat
Function
Existing
Buffer
Moderate
Land Use
Proposed
Buffer
Change
High Impact
Land Use
Proposed
Buffer
Change
Category I
– Bogs Moderate 200 ft. 190 ft. -10 ft. 250 ft. +50 ft.
Category I
– All
Other High 200 ft. 225 ft. +25 ft. 300 ft. +100 ft.
Moderate 125 ft. 110 ft. -15 ft 150 ft. No Change
Low 115 ft. 75 ft. -40 ft. 100 ft. -15 ft.
Category
II High 175 ft. 225 ft. +50 ft. 300 ft. +125 ft.
Moderate 150 ft. 110 ft. -40 ft. 150 ft. No Change
Low 100 ft. 75 ft. -25 ft. 100 ft. No Change
Category
III High 125 ft. 225 ft. +100 ft. 300 ft. +175 ft.
Moderate 100 ft. 110 ft. +10 ft. 150 ft. +50 ft.
Low 75 ft. 60 ft. -15 ft. 80 ft. +5 ft.
Category
IV All Habitat
Functions 50 ft. 40 ft. -10 ft. 50 ft. No Change
This table shows the changes in required buffer distances between wetlands and moderate and
high-impact land uses under new regulations. For each wetland category, habitat function and the
land use impacts (high, moderate, low), it compares the current buffer to what is proposed,
highlighting where setbacks would increase, decrease, or remain unchanged.
These updated buffer rules are designed to give greater protection to wetlands that perform vital
habitat functions, while adjusting or maintaining requirements where risks and functions are lower.
PROPOSED CODE AMENDMENTS
The proposed revisions are based on the latest scientific data. While the details are still being
finalized, it is expected that the updates will include establishing regulations and authority within
the CAO to regulate the Channel Migration Zone, changes to wetland buffer widths, and
incorporating general code cleanup. Staff is proposing changes to the following code section:
• RMC 4-3-050 CRITICAL AREAS REGULATIONS
STAFF RECOMMENDATION
Amend city code, as described above, to align the City’s regulations with Best Available Science by
the end of the year deadline.
IMPACT ANALYSIS
Effect on rate of growth, development, and conversion of land as envisioned in the Plan
There are no anticipated effects on the rate of growth, development, and conversion of land
envisioned in the Plan.
Effect on the City’s capacity to provide adequate public facilities
There are no anticipated effects on the City’s capacity to provide adequate public facilities.
Effect on the rate of population and employment growth
There are no anticipated effects on the rate of population and employment growth created by the
proposed changes.
Whether Plan objectives are being met as specified or remain valid and desirable
Objectives of the Plan would remain valid and desirable.
Effect on general land values or housing costs
There are no anticipated effects on general land values or housing costs.
Whether capital improvements or expenditures are being made or completed as expected
There are no anticipated effects on capital improvements or expenditures created by the proposed
changes.
Consistency with GMA and Countywide Planning Policies
The proposed amendments are consistent with the GMA and Countywide Policies.
Effect on critical areas and natural resource lands
The proposed changes are likely to have a positive impact on critical areas and natural resource
lands by improving protections (e.g., increased wetland buffers).