King County: Updates to Critical Areas Ordinance (CAO)
King County Executive Dow Constantine transmitted a proposed ordinance to King County Council Chair Dave Upthegrove on December 5, 2024, seeking to update the county's critical areas regulations. The existing regulations, last comprehensively revised in 2004, are being updated in accordance with the Growth Management Act (GMA) and Revised Code of Washington. This update, initiated in 2022, involved consultation with Tribes, state and federal agencies, and community partners, and aims to establish updated development limits and requirements for areas surrounding critical areas.
The GMA mandates the use of best available science (BAS) in protecting critical areas and prioritizing the preservation of anadromous fisheries. While adhering to this principle, the proposed ordinance includes some departures from BAS, which are documented in an enclosed October 2024 report. These departures are intended to balance the GMA’s requirements with other planning goals outlined in the King County Comprehensive Plan, such as promoting equity, environmental protection, open space preservation, affordable housing, economic development, property rights, and agriculture. The justification and risk assessment associated with these departures are also detailed in the report.
The proposed ordinance includes several key updates. It increases riparian area widths for all aquatic areas in both rural and urban unincorporated King County. Protections are enhanced for high-value wetlands (Category 1), estuarine wetlands, and coastal lagoons. The ordinance also increases the required mitigation area for unavoidable impacts to wetlands, aquatic areas, and riparian areas. New alluvial fan standards are proposed, allowing flood risk reduction actions in specific circumstances involving river sediment deposits. To support climate resilience, the ordinance allows the use of "climate-smart plants" in mitigation and restoration projects. Finally, it updates provisions for regulatory flexibility within critical areas for agricultural activities, including farm field access drives, grazing, and farm-related structures, under certain conditions.
The letter emphasizes the importance of documenting any amendments to the Critical Areas Ordinance that deviate from BAS, including risk assessments and justifications, as required by state law. The County completed its comprehensive plan update in December 2024 and has until December 2025 to finalize the associated critical areas regulations updates, under a reasonable progress exception. A State Environmental Policy Act (SEPA) review will be conducted by the Executive branch before the County Council takes final action. The update also addresses requirements from the National Marine Fisheries Service’s 2008 Biological Opinion related to the National Flood Insurance Program (NFIP) and Endangered Species Act compliance. King County staff will coordinate with FEMA regarding the CAO review process, including any council amendments, to maintain local NFIP eligibility. The Executive concludes by expressing confidence that the proposed regulations will effectively manage growth while protecting the environment and ensuring GMA compliance.