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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.


The Growth Management Act (GMA) requires all cities and counties in Washington to adopt regulations protecting “critical areas” in order to preserve the natural environment, wildlife habitats, and sources of fresh drinking water. Critical areas regulation also encourage public safety by limiting development in areas prone to natural hazards like floods and landslides.

RCW 36.70A.030(5) defines five types of critical areas:

  1. Wetlands
  2. Areas with a critical recharging effect on aquifers used for potable water
  3. Fish and wildlife habitat conservation areas
  4. Frequently flooded areas
  5. Geologically hazardous areas

Counties and cities are required to develop policies and development regulations to protect the functions and values of critical areas using the best available science (RCW 36.70A.172). All jurisdictions are required to review, evaluate, and, if necessary, revise their critical areas ordinances according to an update schedule. For more information on the schedule and required updates, see our page on the Comprehensive Plan Update Process.

The state Department of Commerce provides many resources for creating an effective critical areas ordinance. The handbook and guidebook below provide a great overview of critical areas issues, as well as detailed guidance for each step in the process (from designating critical areas to specific protection methods and monitoring).

Note: The Department of Ecology has updated their critical areas guidance for wetland buffers as of July 2018. For more information on these changes, see their Local Wetland Regulations webpage.

Best Available Science

GMA requires local governments to use the best available science (BAS) when reviewing and revising their critical areas policies and regulations (RCW 36.70A.172).

Jurisdictions must demonstrate that the best available science has been considered when creating their critical areas ordinance by documenting scientific sources that support their approach to regulating critical areas and explaining when policies depart from science-based recommendations.

The Department of Commerce, Growth Management Services, and the Department of Ecology provide helpful guidance on addressing the GMA's best available science requirements. Examples from local governments in Washington are listed further down in the examples section.

Voluntary Stewardship Program

The Voluntary Stewardship Program (VSP) was created in 2011 and allows participating counties to develop local work plans that use voluntary and incentive-based tools, as an alternative to regulation, to protect critical areas and agricultural lands (see RCW 36.70A.710). Counties had to opt in by early 2012, and 28 counties chose to participate.

Counties participating in VSP create a work plan that is approved by the Washington State Conservation Commission and then implement the plan by recruiting local landowners to participate in incentive-based stewardship activities. Counties report their progress to the Conservation Commission.

See the examples section below.

Critical Areas Update Process

Critical Areas Ordinances must be evaluated and, if needed, revised every eight years. MRSC’s page on the Comprehensive Plan Update Process outlines the process and timeline for these updates in greater detail. The Washington Department of Commerce publishes a Critical Areas Checklist to help local governments update their critical areas ordinance and development regulations. See the examples section below.

Legal References

Examples of Critical Areas Ordinances and Documents

This section provides examples of city and county critical area ordinances and other related documents.

City Ordinances

County Ordinances

Update Processes

Best Available Science

Voluntary Stewardship Programs

Recommended Resources

Several state agencies provide a number of resources specific to each type of critical area. See the links below for more information.


Critical Aquifers Recharge Areas

Fish and Wildlife Habitat Conservation Areas

Frequently Flooded Areas

Geologically Hazardous Areas

Court Decisions

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

Best Available Science

Ferry Cty. v. Growth Mgmt. Hearings Bd., 184 Wn. App. 685 (2014) – The Department of Fish and Wildlife recommended 31 species for consideration for local importance designation in Ferry County. The county did not designate any species of local importance or areas for fish and wildlife conservation. The hearings board decided that Ferry County’s Critical Areas Ordinance was non-compliant with the GMA because it failed utilize the best available science (BAS) or provide a reasoned explanation for deviating from BAS to designate species of local importance or fish and wildlife conservation areas. The superior court ruled in favor of the county, but upon appeal the hearing board decision was reinstated. The court found that the county failed to use BAS and the reasoning provided for their ordinance was unsubstantiated.

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

Growth Management Act (GMA) / Subdivisions

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

Growth Management Act (GMA) / Shorelines Management

KAPO v. Central Puget Sound Growth Mgmt. Hearings Board, 160 Wn. App. 250 (2011) – Following 2010 legislation (Chapter 107, Laws of 2010) that applied retroactively, the court held that the GMA was to regulate critical areas in shoreline areas until such time as Shoreline Management Act plans are updated.

Growth Management Act (GMA)

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

"No Harm" Standard

Swinomish Indian Tribal Community. v. W. Washington Growth Mgmt. Hearings Board, 161 Wn.2d 415 (2007) – 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.

Agricultural Land

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

Last Modified: November 07, 2022