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State Environmental Policy Act

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

New Legislation: Effective July 23, 2023, 2SSB 5412 exempts project actions that develop residential housing units/middle housing within an urban growth area if specified criteria are met, or within a city west of the crest of the Cascade Mountains that meets specified population criteria, from the State Environmental Policy Act (SEPA). We will provide more information on our website soon.


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 ensure 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.

Certain land use actions are "categorically exempt" and do not require SEPA review. See WAC 197-11-720 and WAC 197-11-800.

For proposals requiring SEPA review – whether "project actions" such as the construction or alteration of public buildings, infrastructure, or private projects, or "non-project actions" such as the development of plans, ordinances, programs, or administrative rules – the lead government agency must make a "threshold determination" to determine whether the project is likely to have any significant adverse environmental impact. 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.

The threshold determination process will result in either a Determination of Nonsignificance (DNS) or a Determination of Significance (DS).

If the lead agency issues a Determination of Significance, preparation of a detailed environmental impact statement (EIS) will be required. Under state law, lead agencies must "aspire" to prepare the final EIS in as expeditious a manner as possible without compromising the integrity of the analysis. Specifically, state law calls upon lead agencies to prepare the final EIS within two years for the most complex decisions and to "far outpace" that timeframe for more straightforward decisions (RCW 43.21C.0311).

SEPA also allows for "planned actions" in which an EIS can be prepared in advance for a specific geographic area before individual projects are proposed, which then facilitates the environmental review of subsequent individual development projects. For more information, see our page Planned Action.

As the agency responsible for implementing state regulations, DOE maintains a wealth of information for local governments regarding SEPA on their website. In particular, we recommend you review the following resources:

Statutes and Administrative Regulations

Examples of Codes, Policies, and Procedures

City Codes

County Codes

Special Purpose District Policies and Procedures

Court Decisions

The following list of case summaries highlights key court decisions on SEPA issues that might be of special interest to local governments. This is not intended to be a comprehensive list of SEPA related court cases.

County correctly issued a determination of nonsignificance (DNS) on its land use code governing winery, brewery, and distillery facilities.

King County v. Friends of Sammamish Valley (2023) – This case involved challenges to a King County ordinance amending its land use code governing winery, brewery and distillery facilities. The ordinance was challenged before the Growth Management Hearings Board; the primary claim was that the ordinance would result in a proliferation of the facilities, which would have significant environmental consequences that the county failed to recognize and evaluate. The board agreed and invalidated the ordinance. The court reversed the board’s order of invalidity, concluding that the ordinance isn’t likely to lead to plaintiff’s predicted development and the county was correct in issuing its DNS. The court remanded the matter to the Board with instructions to reinstate the DNS and enter a finding of GMA and SEPA compliance. 

A legislative amendment to SEPA that eliminated the ability to review SEPA-related light and glare claims applied to a pending case challenging a development based on light and glare.

Fischer Studio Building Condominium Owners Assoc. v. City of Seattle (2023) — Fischer appealed the city’s design review approval of a proposed apartment building across an alley. Fischer first challenged the threshold determination that the proposal was not likely to have a probable adverse impact on the light and glare of the environment under SEPA. While the appeal was pending, the legislature modified SEPA to eliminate the ability to appeal based on light and glare for projects that are subject to local design review requirements, which curtailed the court’s authority to review SEPA-related light and glare claims. Because the amendment became effective while the case was pending appeal, the court was required to dismiss the light and glare claims. The second challenge claimed the city’s design review board applied its guidelines inconsistently as compared to an unrelated prior proposal for the same site; the court dismissed this claim because Fischer didn’t identify any specific guidelines the Board applied inconsistently and failed to identify which of the LUPA standards in RCW 36.70C.130 applied to their challenge.

When a local government assumes lead agency status from another local government, the threshold determination made by the former lead agency is void, but the SEPA process does not need to start all over again. Only decisions made in reliance on the threshold determination that implicate SEPA are void.

City of Puyallup v. Pierce County, 20 Wash. App. 2d (2021) — Pierce County issued a mitigated determination of nonsignificance (MDNS) under SEPA for a warehouse distribution project bordering the City of Puyallup. Puyallup attempted to assume lead agency status so it could issue a determination of significance (DS) and prepare an EIS. In prior litigation between the city and the county, the Washington Court of Appeals ruled that the city could assume lead agency status. 

On remand, the city argued that all county reviews, decisions, permits and approvals related to the project were null and void. The county argued that only decisions based on the MDNS were void and that land use applications for the project should be returned to the status of pending applications. 

The court ruled that the city’s order was too broad. Even though the MDNS was void, the SEPA regulations provide that reliance on decisions and reviews from a prior SEPA process “is logical and even required.”  On the other hand, the court noted that the county’s proposed order (which was adopted by the trial court) was flawed because it did not explicitly state that the MDNS was void.

See earlier 2019 decision below.

A city that has authority over (parts) of a proposal is an agency with jurisdiction for purposes of SEPA and, if an MDNS is issued, it may assume lead agency status.

City of Puyallup v. Pierce County, 8 Wash. App. 2d 323 (2019) — A developer sought to construct a warehouse, distribution and freight center in an area adjacent to the City of Puyallup and within the city’s Urban Growth Area. The project would be served by city sewer and partially by city water. Due to the increased traffic the project would create, street improvements would be required to the city’s street system. The county, after SEPA review, issued an MDNS requiring, among other things, that street improvements be made to city streets. Thereafter, the city issued a “Notice of Assumption of Lead Agency Status” and made a Determination of Significance (DS) for the project. The county objected, stating it would not recognize the city’s action. A lawsuit was brought, and the trial court found in the county’s favor. The city appealed.

On appeal, the court of appeals reversed. The city can become an “agency with jurisdiction” if it can show that “it has authority to approve, veto, or finance parts of the proposal.”  The city argued that, since it had authority over the required street improvements and must approve the sewer and water connections and service, it was an agency with jurisdiction. The county and developer disagreed, arguing that required work in the city was not part of the proposal and the city did not qualify as its role was that of a service provider.  The court concluded that the city, based upon the plain meaning of WAC 197-11-948, was an agency with jurisdiction due to its responsibilities over the street improvements and provision of sewer and water. An agency with jurisdiction may assume lead agency status if a DNS is issued. Although the county disagreed, the court concluded that an MDNS is a type of DNS, thus allowing the city to assume lead agency status.

See subsequent 2021 decision above.

Lease option to conduct feasibility studies was not a "project action" and therefore not subject to SEPA review.

City of Mukilteo v. Snohomish Cty., (unpublished) review denied, 188 Wn.2d 1019, 397 P.3d 119 (2017) — The court held that a lease option to conduct feasibility studies for commercial airline service at a portion of Paine Field was not a "project action" under WAC 197–11–704(2)(a)(ii). The option is not a decision to “[p]urchase, sell, lease, transfer, or exchange natural resources, including publicly owned land, whether or not the environment is directly modified.” Rather, the option granted a contractual right to enter the airport property to conduct feasibility studies and the right to exercise the option to lease the property at a later time. The county was therefore not required to complete a SEPA review before executing the option to lease because this option does not fall within this definition.

Lease did not bind the port so as to limit reasonable alternatives under SEPA.

Columbia Riverkeeper v. Port of Vancouver, 188 Wn.2d 80 (2017) — An environmental group brought a SEPA challenge against the Port of Vancouver, arguing that entering into a lease for a proposed petroleum facility prior to completion of an EIS violated the SEPA requirement that prohibits agency action that limits reasonable alternatives prior to completion of an EIS. Siting of the facility was subject to the Energy Facility Site Evaluation Council (EFSEC) approval. The lease included language stating that Tesoro could not occupy or develop the port property until Tesoro obtained “all necessary licenses, permits and approvals…for the Permitted Use.” The court held that the SEPA provision at issue did apply to the port, however the lease had sufficient escape clauses such that the port did not violate SEPA by entering into the agreement. 

Open record hearing required on SEPA appeal

Ellensburg Cement Products, Inc. v. Kittitas County, 179 Wn.2d 737 (2014) — 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. Since the county provided an administrative SEPA appeal process, the state supreme court held that the county 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.

Environmental Impact Statement (EIS) required

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

Douglass v. City of Spokane Valley, 154 Wn. App. 408 (2010) — 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.

Postponement of environmental analysis

Spokane County v. E. Wash. Growth Mgmt. Hearings Bd., 176 Wn. App. 555 (2013) — 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.

Memorandum of Understanding (MOU) not an "action"

Int'l Longshore & Warehouse Union, Local 19 v. City of Seattle, 176 Wn. App. 512 (2013) — 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.

SEPA challenge to comprehensive plan and zoning code amendments

Davidson Serles & Assocs. v. City of Kirkland, 159 Wn. App. 616 (2011) — 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).

Legal support for mitigation condition

Brinnon Group v. Jefferson County, 159 Wn. App. 446 (2011) — 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.

Fluoridation decision exempt from SEPA review

Clallam County Citizens for Safe Drinking Water v. City of Port Angeles, 137 Wn. App. 214 (2007) — 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.

Condemnation proceedings are not subject to SEPA

Regional Transit Authority v. Miller, 156 Wn.2d 403 (2006)

Hearing examiner jurisdiction

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

Review authority over plat mitigation

City of Olympia v. Thurston County Bd. of Comm'rs, 131 Wn. App. 85 (2005), review denied, 158 Wn.2d 1003 (2006) — 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 procedures for seeking review of the threshold determination. A mitigation measure is not a threshold determination under SEPA rules.

SEPA EIS is not required when an adequate EIS has been previously prepared under NEPA

Boss v. Department of Transportation, 113 Wn. App. 543 (2002) — When an adequate environmental impact statement (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.

Supplemental EIS not required

Thornton Creek Legal Defense Fund v. Seattle, 113 Wn. App. 34 (2002), review denied, 149 Wn.2d 1013 (2003) — 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.

Cumulative impacts

Boehm v. City of Vancouver, 111 Wn. App. 711 (2002) — 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.

SEPA / GMA integration

Moss v. City of Bellingham, 109 Wn. App. 6 (2001), review denied, 146 Wn.2d 1017 (2002) — 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. 

Supplemental EIS

Wells v. Water Dist. 10, 105 Wn. App. 143 (2001) — 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.

Mitigated DNS

West Coast, Inc. v. Snohomish County, 104 Wn. App. 735 (2000) — 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.

Lead agency status

Bellevue Farm Owners Assoc. v. Shorelines Hearings Bd., 100 Wn. App. 341 (2000) — 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.

Consideration of alternatives

King County v. Cent. Puget Sound Bd., 138 Wn.2d 161 (1999) — 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.

Availability of writ of review

Saldin Sec. v. Snohomish County, 134 Wn.2d 288 (1998) — 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.

Conclusory findings of adverse impacts

Hayes v. City of Seattle, 131 Wn.2d 706 (1997) — 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.

EIS adequacy

Kiewit Construction v. Clark County, 83 Wn. App. 133 (1996) — 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.

EIS adequacy / phased review

Opal v. Adams County, 128 Wn.2d 869 (1996) — 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.

Last Modified: August 11, 2023