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Critical Areas

This page provides an overview of the critical areas regulations required of all cities, towns, and counties in Washington State under the Growth Management Act.


All cities and counties in Washington are required to adopt critical areas regulations by the Growth Management Act (GMA) (RCW 36.70A.060). As defined by the GMA in RCW 36.70A.030(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.

Counties and cities are required to include the best available science in developing policies and development regulations to protect the functions and values of critical areas (RCW 36.70A.172). All jurisdictions are required to review, evaluate, and, if necessary, revise their critical areas ordinances according to an update schedule. MRSC's page on the Periodic Update Process for Comprehensive Plans and Development Regulations provides additional information on the schedule and required updates.

General Critical Areas Information

Some of the handbooks and guidance materials are older; however, they provide useful general information for updating critical areas ordinances.

Legal References

Statutes and Administrative Regulations

Court Decisions

This section contains a selected list of court decisions about critical areas and the Growth Management Act.

Yakima County v. E. Wash. Growth Mgmt. Hearings Bd., 168 Wn. App. 680 (2012) – Best Available Science

The hearings board decided that the county's standard stream buffers were unsupported by the best available science, and that the minimum adjustments allowed to be made to stream and wetland buffers failed to comply with the GMA. The court of appeals held that the superior court erroneously reversed the hearings board's decision on stream buffer widths, noting that the record did not show the county systematically analyzed the efficacy of the stream buffers in place since 1995, or that “for the most part” these buffers had adequately performed their intended function. However, the court of appeals ruled that the superior court properly reversed the hearings board's decision to invalidate the county's decision not to designate and regulate type 5 ephemeral streams under the county's critical areas ordinance. The court determined that the county provided a reasoned justification in deciding not to designate or regulate ephemeral streams as critical areas.

Olympic Stewardship Found. v. W. Wash. Growth Mgmt., 166 Wn. App. 172 (2012), review denied, 174 Wn.2d 1007 (2012) - Best Available Science

Olympic Stewardship Foundation challenged the county's vegetation regulations applicable to rivers subject to channel migration, arguing that the regulations violated the GMA's "best available science" requirement and that the Legislature's 2010 amendment to RCW 36.70A.480 invalidates the county's nonconforming use regulation for critical areas. The court held there was no duty on a county to describe each step of the deliberative process that links the science that it considers to the adopted policy or regulation; rather, the county must address on the record the relevant sources of best available scientific information included in the decision-making. The court also found that, by prohibiting vegetation removal and development only within those areas determined to be "high risk" critical areas, any dedications of land within the critical areas are de facto "reasonably necessary as a direct result of the proposed developments," in compliance with RCW 82.02.020.

Stevens County v. E. Wash. Growth Mgmt. Hearings Bd., 163 Wn. App. 680 (2011), review denied, 173 Wn.2d 1019 (2012) - GMA/Subdivisions

The court concluded that the county subdivision code failed to protect critical areas, as required by the GMA. Significantly, the code did not address impervious surface coverage in multiple important contexts, it did not apply county-wide, and it did not mention methods for addressing storm water or impervious surface coverage.

KAPO v. Central Puget Sound Growth Mgmnt. Hearings Board, 159 Wn. App. 270 (2011) - GMA/Shorelines Management

Following 2010 legislation (Chapter 107, Laws of 2010) that applied retroactively, the court held that the Growth Management Act was to regulate critical areas in shoreline areas until such time as Shoreline Management Act plans are updated.

Stevens County v. Futurewise, 146 Wn. App. 493 (2008), review denied, 165 Wn.2d 1038 (2009) - GMA

The court held that substantial evidence supported the growth board's decision that the county's critical habitat code provisions did not comply with the GMA, because the county failed to designate all critical habitats and failed to consider the best available science in designating critical habitats, as required by RCW 36.70A.172(1). The county had to use some kind of scientific methodology in a reasoned process of analysis to designate the habitats.

Swinomish Indian Tribal Community. v. W. Washington Growth Mgmnt. Hearings Board, 161 Wn.2d 415 (2007) - "No Harm" Standard

The tribe challenged the county's critical areas ordinance alleging, among other things, that a "no harm" provision failed to protect critical areas, as required by RCW 36.70A.060(2). The court concluded that the "no harm" standard protected critical areas by maintaining existing conditions. The GMA does not impose a duty on local governments to enhance critical areas. The county did not need to require buffers near rivers, where previously existing buffers had long since been removed (there is no requirement to enhance). The court also concluded that, while best available science needed to be considered and included in its record, the county did not need to follow it. A county may depart from the best available science if it provides a reasoned justification for doing so.

Clallam County v. W. Washington Growth Mgmnt. Hearings Board, 130 Wn. App. 127 (2005), review denied, 163 Wn.2d 1053 (2008) - Agricultural Land

The court concluded that preexisting agricultural uses are not exempt from all critical areas regulation. The court also held that the county was not limited to exempting only designated agricultural resource land from full critical areas regulation and that it may expand its exempt agricultural land to meet its local conditions. However, the county must balance such expanded exemption with corresponding restrictions that take into account the specific harms threatened by the expanded class of farm lands.

Best Available Science (BAS)

Under the state GMA, local governments are required to use the best available science when reviewing and revising their policies and regulations on critical areas. The Department of Commerce, Growth Management Services, and the state Department of Ecology have provided helpful guidance on addressing the GMA's best available science requirements.

Critical Areas Updates

The following includes materials related to updating critical areas ordinances from cities and counties in Washington State.

Examples of City Ordinances

  • Bainbridge Island Municipal Code Ch. 16.20 - Critical Areas
  • Bothell Municipal Code Ch. 14.04 - Critical Area Regulations
  • Bremerton Municipal Code Ch. 20.14 - Critical Areas*
  • Ellensburg Municipal Code
  • Mount Vernon Municipal Code Ch.15.40 – Critical Areas 
  • Mukilteo Municipal Code Ch. 17.52 - Critical Areas Regulations*
  • Olympia Municipal Code Ch. 18.32 - Critical Areas
  • Port Townsend Municipal Code Ch. 19.05 - Critical Areas*
  • Redmond Zoning Code Ch. 21.64 - Critical Areas Regulations

* Local example recommended by Washington State Department of Commerce, Growth Management Services

Examples of County Ordinances

Examples of Handouts and Application Forms

A few examples of critical areas handouts and application forms are presented here.

Recommended Resources

Last Modified: August 07, 2017