CAOs Must Balance Environment and Housing

Under Washington’s Growth Management Act (GMA), every city is required to adopt and enforce a Critical Areas Ordinance (CAO) to protect environmentally sensitive areas and safeguard the public from natural hazards. Cities must update their CAOs every 10 years using the Best Available Science. While the original deadline was the end of 2024, cities now have until December 2025 to complete their updates.

CAOs aim to preserve natural habitats, maintain species diversity, and prevent hazards. The GMA identifies five types of critical areas that cities must protect:

1. Wetlands
2. Critical Aquifer Recharge Areas
3. Fish and Wildlife Habitat Conservation Areas
4. Frequently Flooded Areas
5. Geologically Hazardous Areas

Historically, courts and hearings boards prioritized environmental protection over other GMA goals, contrary to legislative intent. The Legislature has since clarified—twice—that all GMA goals must be balanced, including housing, economic development, and environmental protection.

Each city must align its CAO with its Comprehensive Plan, which in turn must comply with Countywide Planning Policies and the GMA. Development regulations, including CAOs, must reflect this balance.

However, state agencies like the Department of Fish and Wildlife often advocate for larger buffers and stricter restrictions, which can conflict with cities’ obligations to accommodate housing under RCW 36.70A.020(4).

Seattle King County REALTORS® emphasize the need for cities to uphold the legislative mandate for balanced planning. REALTORS® should stay engaged as cities finalize their CAO updates to ensure housing needs are not overlooked.

Covington: REALTORS® Testify on CAO to Allow More Housing

In testimony before the Covington Planning Commission, Seattle King County REALTORS® (SKCR) urged the city to balance  environmental protection with its legal obligation to accommodate housing under HB 1220. SKCR supported the city’s science-based approach to stream buffer calculations, which rejected outdated methods based on theoretical tree heights in favor of locally observed conditions. They also advocated for maintaining current setback standards and preserving buffer averaging—tools essential for infill development and middle housing under HB 1110.  Alongside the Master Builders Association (MBAKS), SKCR emphasized that cities must not consider CAO updates in isolation, but rather as part of a broader planning framework that includes housing feasibility and affordability.

Renton: CAO Update Includes Code Cleanup, CMZ Mapping, and Wetland Protections

Renton’s Planning Commission held a public hearing on proposed updates to the city’s CAO, introducing three main categories of changes. First, a “code cleanup” will clarify regulatory language and references, and allow exemptions for routine maintenance and new trail construction. Second, new Channel Migration Zone (CMZ) regulations will expand mapping of stream corridors at risk of erosion or flooding, incorporate King County’s 2015 Cedar River study, and allow site-specific reassessments of CMZ boundaries.  Third, updated wetland protection standards will apply Best Available Science to buffer requirements, integrate detailed tables for mitigation ratios, and establish clear criteria for buffer reductions and averaging. These changes aim to improve ecological outcomes while providing regulatory clarity for future development.