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State Environmental Policy Act

This page provides an overview of the State Environmental Policy Act (SEPA) in Washington State, including relevant court decisions and examples of local code provisions.


The State Environmental Policy Act (SEPA), Washington State's most fundamental environmental law, was enacted in 1971 as chapter 43.21C RCW. SEPA's basic policy of maintaining and improving environmental quality is implemented primarily through extensive procedural requirements designed to insure that governmental agencies give proper consideration of environmental matters in making decisions on actions, whether proposed by private parties or the governmental entities themselves, that may impact the environment. If initial governmental review of a proposed action indicates that the action will have probable and significant adverse environmental impacts, preparation of a detailed environmental impact statement (EIS) will be required. The procedural requirements governing this environmental review process are contained in detailed regulations enacted by the Department of Ecology (DOE) in chapter 197-11 WAC.

In 2ESSB 6406, the 2012 legislature enacted a number of amendments to SEPA and directed DOE to update its SEPA regulations to increase the range of activities that are exempted from SEPA review.. 

Legal References

Statutes and Administrative Regulations

Selected Recent Court Decisions

Ellensburg Cement Products, Inc. v. Kittitas County, 179 Wn.2d 737 (2014) – Open record hearing required on SEPA appeal

The county considered the appeal of a DNS for a conditional use permit application for rock crushing and related activities on agricultural-zoned property in a "closed record" hearing, and it then held an "open record" public hearing on the underlying permit application. The state supreme court held that the county, because it provided an administrative SEPA appeal process, was statutorily required to hold an "open record hearing" on the appeal of the SEPA DNS. The SEPA appeal hearing must be consolidated and simultaneous with the hearing on the underlying permit decision, and must provide for the preparation of a record, including testimony under oath, for use in subsequent proceedings.

Lands Council v. Wash. State Parks & Recreation Comm'n, 176 Wn. App. 787 (2013) – EIS required

The commission issued a mitigated determination of nonsignificance (MDNS) for its classification of an area in the state park as “recreation,” allowing development of skiing facilities. The classification was conceptual in nature and subject to modification of specific locations of proposed facilities. The MDNS included a commitment to future EIS preparation when an actual detailed development proposal is made. The court held that an EIS is required before an agency makes an official classification of land if the classification would effectively approve a proposed development as described in a conceptual plan, subject only to specific siting decisions.

Spokane County v. E. Wash. Growth Mgmt. Hearings Bd., 176 Wn. App. 555 (2013) – Postponement of environmental analysis

The court emphasized that, for a nonproject action such as a comprehensive plan amendment or rezone, the agency must address the probable impacts of any future project action the proposal would allow. Thus, the hearings board did not err in finding SEPA noncompliance because the County failed to fully disclose or carefully consider the comprehensive plan amendment's environmental impacts before adopting it and at the earliest possible stage under RCW 43.21C.030(2)(c) and WAC 197-11-330(1). The hearings board properly recognized that the SEPA checklist could not postpone environmental analysis to the project review stage because the comprehensive plan amendment approved the property's existing nonconforming use, thereby affecting the environment even if the property owners or their successors never pursue subsequent project action.

Int'l Longshore & Warehouse Union, Local 19 v. City of Seattle, 176 Wn. App. 511 (2013) – MOU not an "action"

A memorandum of understanding (MOU) specifying city and county participation in the financing and operation of the proposed sports arena was not an "action" under SEPA because their commitments were expressly contingent on a future decision to proceed with their participation in the project after completion of an EIS. The MOU was not an “action” because, by itself, it had no environmental impact.

Davidson Serles & Assocs. v. City of Kirkland, 159 Wn. App. 616 (2011) – SEPA challenge to comprehensive plan and zoning code amendments 

The Growth Management Hearings Board has exclusive jurisdiction to review challenges to comprehensive plans and development regulations that are based on SEPA. Also, no EIS is required for planned action projects because the environmental impacts of the individual planned action projects will have been addressed in an EIS prepared earlier in conjunction with one of the six activities listed in RCW 43.21C.031(2)(a)(ii).

Brinnon Group v. Jefferson County, 159 Wn. App. 446 (2011) – Legal support for mitigation condition

A single citation to an environmental policy in support of several mitigation conditions may be sufficient to satisfy the requirement in WAC 197-11-660(1) that the basis for a mitigation condition delineated in an environmental impact statement be supported by citation to an environmental protection policy. Nothing in RCW 43.21C.060, which authorizes mitigation conditions, or WAC 197-11-660(1), which establishes the citation requirement, requires a government agency to separately cite an environmental policy for each mitigation condition specified in an environmental impact statement. of the rule.

Douglass v. City of Spokane Valley, 154 Wn. App. 408 (2010) – EIS requirement upheld

The court upheld the hearing examiner's decision reversing the city planning department and requiring preparation of an EIS for a proposed housing development to address egress from the area of the proposed development (an area of high fire risk) in the event of a firestorm event that would require evacuation of the area.

Clallam County Citizens for Safe Drinking Water v. City of Port Angeles, 137 Wn. App. 214 (2007) – Fluoridation decision exempt from SEPA review

A city council's decision to fluoridate the public water supply is categorically exempt from environmental review under SEPA. However, nothing in SEPA or the SEPA rules precludes an agency from issuing a DNS on a project determined to be categorically exempt.

Regional Transit Authority v. Miller, 156 Wn.2d 403 (2006) – Condemnation proceedings are not subject to SEPA.

In re Jurisdiction of King County Hearing Examiner, 135 Wn. App. 312 (2006) –  Hearing examiner jurisdiction

The court held that the hearing examiner lacked jurisdiction to hear a challenge to a supplemental EIS after having a decision upholding the adequacy of the final EIS. Also, RCW 43.21C.240 allows counties and cities to determine that a project's environmental impact will be mitigated through its own development regulations and existing environmental documents.

City of Olympia v. Thurston County Bd. of Comm'rs, 131 Wn. App. 85 (2005), review denied, 158 Wn.2d 1003 (2006) – Review authority over plat mitigation

Where a mitigation measure identified in a mitigated determination of nonsignificance is required as a condition of plat approval, review is according to procedures for review of the plat, not according to proceduress for seeking review of the threshold determination. A mitigation measure is not a threshold determination under SEPA rules.

Boss v. Department of Transportation, 113 Wn. App. 543 (2002) – Previously prepared NEPA EIS   

When an adequate EIS has been previously prepared under the National Environmental Policy Act (NEPA) for the same project, a SEPA EIS is not required, under RCW 43.21C.150.

Thornton Creek Legal Defense Fund v. Seattle, 113 Wn. App. 34 (2002), review denied, 149 Wn.2d 1013 (2003) – Supplemental EIS not required

A proposed development's effect upon a hypothetical habitat restoration project is not an adverse environmental impact under SEPA. Also, the city's circulation of a "notice of availability" of an EIS addendum rather than a "notice of adoption" of the addendum, as required by law, was harmless error.

Boehm v. City of Vancouver, 111 Wn. App. 711(2002) – Cumulative impacts

An analysis of the cumulative impacts of a proposed project is not required under SEPA unless (1) there is some evidence that the project will facilitate future action that will result in additional impacts or (2) the project is dependent on subsequent proposed development. A project's cumulative impacts that are merely speculative need not be considered.

Moss v. City of Bellingham, 109 Wn. App. 6 (2001), review denied, 146 Wn.2d 1017 (2002) – SEPA/GMA integration

The city granted preliminary plat approval after issuing a determination of nonsignificance, thus obviating the need for preparation of an EIS. RCW 43.21C.240, as implemented by WAC 197-11-158, substantially streamlined the threshold determination process for cities and counties planning under the GMA by authorizing the SEPA official to rely on existing plans, laws, and regulations in meeting SEPA requirements.The preliminary plat approval included numerous conditions in mitigation of the environmental impacts of the proposed development. The court held that an environmental impact statement was not required where the requirements of the local comprehensive plan and regulations and conditions of plat approval mitigated all of the significant environmental impacts of the proposed development. 

Wells v. Water Dist. 10, 105 Wn. App. 143 (2001) – Supplemental EIS

An agency is not required to supplement an existing final environmental impact statement (FEIS) where new information regarding a project's potential impacts does not establish that significant adverse impacts are probable, meaning reasonably likely to occur. The mere possibility of those impacts occurring is not sufficient to require a supplement to the FEIS. A claim that "new information" requires supplementation of an FEIS is subject to the 21-day limitation in RCW 43.21C.080(2)(a) for challenging a governmental action under SEPA. A challenge after that 21-day period is not allowed unless there has been a substantial change in the proposed action that would likely have new significant adverse impacts or an impact previously identified as needing further evaluation.

West Coast, Inc. v. Snohomish County, 104 Wn. App. 735 (2000) – Mitigated DNS

A developer granted preliminary plat approval for which a final and binding mitigated determination of nonsignificance (MDNS) has been issued may not undermine that determination by seeking revision of the preliminary plat in an attempt to remove an express condition of plat approval on which the MDNS is based.

Bellevue Farm Owners Assoc. v. Shorelines Hearings Bd., 100 Wn. App. 341 (2000) – Lead agency status

An agency has jurisdiction under SEPA if it must issue permits or approvals for the project. WAC 197-11-714(3). Another agency with SEPA jurisdiction cannot change a DNS unless it assumes lead agency status. WAC 197-11-390(2)(b). If another agency assumes lead status under WAC 197-11-948(1), the new lead agency can review the underlying materials and reverse the first lead agency's DNS. The new lead agency can then order preparation of an EIS. WAC 197-11-948(2). But the county's DNS for a proposed shoreline development did not preclude the Shorelines Hearings Board from later denying the permit for proposed development because of environmental impact.

King County v. Cent. Puget Sound Bd., 138 Wn.2d 161 (1999) – Consideration of alternatives

SEPA directs that "alternatives to the proposed action" be included in an EIS. Also, SEPA rules mandate consideration of "reasonable alternatives," which are defined as less environmentally costly action that could feasibly attain or approximate a proposal's objectives. An alternative considered for purposes of an EIS need not be legally certain or uncontested, it must only be reasonable. Thus, consideration of a one-acre lot subdivision as an alternative to the proposed urban planned development is permissible, even if the one-acre alternative may not legally be available as an option.

Saldin Sec. v. Snohomish County, 134 Wn.2d 288 (1998) – Availability of writ of review

Property owners who proposed to develop nearly 100 acres into separate residential subdivisions filed petitions for constitutional writs of certiorari seeking judicial review of the county council's decision requiring preparation of a limited EIS with respect to the issue of potential groundwater contamination. The county deferred action on the preliminary plat applications until completion of the EIS. SEPA, specifically RCW 43.21C.075(6)(c), requires that judicial review of any SEPA determination be coupled with an appeal of the final action on an application. The court held that SEPA did not provide effective review of the county council's requirement of an EIS, and that a constitutional writ of review is available if the project proponent alleges facts that, if verified, indicate that the council's decision was illegal or arbitrary and capricious. Here, the project proponent did not allege such facts.

Hayes v. City of Seattle, 131 Wn.2d 706 (1997) – Conclusory findings of adverse impacts

The city's decision to condition the grant of a master use permit on a reduction in the length of the proposed building was conclusory and, contrary to SEPA, did not specifically describe the adverse impact of the project or explain how reducing the size of the project would mitigate any such adverse impact.

Kiewit Construction v. Clark County, 83 Wn. App. 133 (1996) – EIS adequacy

Kiewit appealed the county's decision to require a supplemental EIS for a proposed asphalt manufacturing plant or, alternatively, to require Kiewit to construct a ramp from the site to a nearby freeway as a condition of granting the requested permit. The county required the supplemental EIS because it deemed the original EIS to be inadequate. The court, in upholding the county's decision, cited the rule that the legal adequacy of an EIS is tested under a rule of reason. Under this rule, an EIS is adequate if it provides a reasonably thorough discussion of the significant aspects of the probable environmental consequences of the proposed activity and presents sufficient information to allow the governmental decision maker to make a reasoned choice among alternatives. In addition to deciding that the requirement of the supplemental EIS satisfied this test, the court concluded that approval of the permit conditioned on the construction of a freeway ramp was a valid alternative to the supplemental EIS requirement.

Opal v. Adams County, 128 Wn.2d 869 (1996) – EIS adequacy/phased review

The plaintiff land preservation organization appealed the county's decision to grant a permit authorizing the use of a site in the county for a proposed regional solid waste landfill and recycling facility. Among other things, the plaintiff argued that the EIS should have included consideration of offsite alternatives. The court disagreed, concluding that this was a private project for which SEPA does not require consideration of alternatives. In looking at whether this was a public or private project, the court considered (1) which entity primarily sponsored or initiated the project and (2) whether the public entity is seeking to fulfill its responsibility to perform a traditional governmental function by way of a private project. The court also concluded that phased environmental review of this project was appropriate.


  • Bainbridge Island Municipal Code Ch. 16.04 - Environmental Policy
  • Bonney Lake Municipal Code Ch. 16.04 - Environmental Policy Act
  • Bothell Municipal Code Ch. 14.02 - State Environmental Policy Act
  • Chelan Municipal Code Ch. 14.06 - Environmental Procedures and Policies 
  • Clallam County Code Ch. 27.01 - Clallam County Environmental Policy
  • Federal Way Municipal Code Title 14 - Environmental Policy
  • Kent Municipal Code Ch. 11.03 - Environmental Policy  
  • Sultan Municipal Code Ch. 17.04 - State Environmental Policy Act
  • Sumner Municipal Code Ch. 16.04 - SEPA Procedures and Policies 
  • Whatcom County Code Ch. 16.08 - State Environmental Policy Act

Additional References

Last Modified: January 16, 2018