The Evolving "Best Available Science" Standard in Washington Land Use and Environmental Regulation

Governor Bob Ferguson's Executive Order 25-10, issued October 22, 2025, calls for a more meaningful, accountable relationship between Washington state and Tribal Nations. The Order directs all cabinet agencies to strengthen government-to-government consultation, increase collaboration with Tribal Nations in developing policies and programs, and build Tribal staff capacity. Notably, for land use and environmental regulation, state agencies must also incorporate tribally accepted Indigenous Knowledge into decision-making, research, policy development, interpretations, outcomes, findings, and recommendations when setting standards or making decisions based on "best available science." This change will directly affect how state agencies like Ecology, Fish & Wildlife, Natural Resources, and WSDOT make decisions and set standards related to wetland buffers, wildlife habitat, stormwater systems, geologic hazard areas, and major infrastructure projects.

As described in the Order, Indigenous Knowledge is a system of local and global observations, oral and written knowledge, practices, and beliefs that promote environmental sustainability and the responsible stewardship of natural resources through relationships between humans and environmental systems. As agencies begin implementation, this shift could also influence state guidance that local governments must follow, potentially leading to updated standards for local critical areas regulations and project review under the State Environmental Policy Act (SEPA).

Over the coming year, expect new guidance and engagement processes as Washington agencies align their practices with the Order and elevate Indigenous perspectives in shaping the future of the state's land use and environmental governance.