The Washington State Growth Management Act (the "GMA" codified in Chapter 36.70A RCW) presents 13 planning goals (RCW 36.70A.020).

Goal 10 is Environment

Protect the environment and enhance the state's quality of life, including air and water quality, and the availability of water.

The law requires counties and cities to designate and protect "critical areas," a GMA term that encompasses sensitive environmental features.

RCW 36.70A.030 Definitions. (5): "Critical areas" include the following areas and ecosystems: (a) Wetlands; (b) areas with a critical recharging effect on aquifers used for potable water; (c) fish and wildlife habitat conservation areas; (d) frequently flooded areas; and (e) geologically hazardous areas.

For critical areas, the definitions section of the Act at .030 includes (9) "Geologically hazardous areas" and (20) "Wetland" or "wetlands."

The State Legislature directed the State Department of Community, Trade & Economic Development (CTED) to adopt rules to implement GMA. RCW 36.70A.050 tasks CTED with adopting minimum guidelines to classify critical areas; these were adopted in 1991 as WAC 365-190-080 within Chapter 365-190 WAC. Definitions related to critical areas-beyond those in the GMA-appear in WAC 365-190-030.

Best Available Science Requirement

RCW 36.70A.172 Critical areas-Designation and protection-Best available science to be used. The GMA was amended in 1995 to include the requirement that local jurisdictions consider "best available science" (BAS) when establishing protection measures for critical areas.

The State Legislature directed CTED to adopt rules to implement the BAS requirement. The adopted rules form Part Nine of Chapter 365-195 WAC.