Skip to main content

Thurston County, Washington

Critical Areas Ordinance Title 24


Thurston County critical area regulations are detailed in Title 24 of the County Code of Ordinances.

Last Critical Areas Code Update: 2012.


Why the County Regulates Critical Areas: State Law Requires Protections for Five Areas

Washington state law RCW 36.70-Growth Management Act (GMA) requires cities and counties to limit development in five critical areas, including:

  • Frequently flooded areas  Fact Sheet.
  • Geologically hazardous areas (example: landslide zones)  Fact Sheet.
  • Land that drains into drinking water aquifers (also called Critical Aquifer Recharge Areas)  Fact Sheet.
  • Important fish and wildlife habitat areas  Fact Sheet.
  • Wetlands  Fact Sheet.


The first critical areas ordinance was adopted by Thurston's Board of County Commissioners in 1994, in response to the Washington Legislature enacting the Growth Management Act (GMA) in 1990. A GMA update in 2003 required counties to review and update critical area regulations every seven years to align with any state and federal law changes.