​SEPA Guide for lead agencies

​This guidance is designed for local governments and state agencies responsible for leading the environmental evaluation of projects and actions under the State Environmental Policy Act (SEPA). 


​The State Environmental Policy Act (SEPA) is intended to provide information to local governments, state agencies, applicants, and the public to encourage the development of environmentally-sound proposals. Under the 1971 law, the environmental review process involves:

  • Identifying and evaluating probable environmental impacts.
  • Developing mitigation measures to reduce adverse environmental impacts.

This environmental information, along with other considerations, is used by local and state decision-makers to decide whether to approve a proposal, approve it with conditions, or deny the proposal.

SEPA applies to actions made at all levels of government in Washington. Agency decisions are the hub of SEPA if there is no agency action, SEPA is not required.
Our SEPA rules provide the basis for implementing SEPA, and establish uniform requirements for all agencies. By opening up the decision-making process providing an avenue for consideration of environmental consequences, agencies and applicants are able to develop better proposals.  Agencies may also deny proposals that are environmentally unsound.

Agency actions

SEPA environmental review is required for any state or local agency decision that meets the definition of an “action” and is not categorically exempt. Actions are divided into two categories: Project Actions and Nonproject Actions. 

Project actions 

These are agency decisions to license, fund, or undertake a specific project. For example, project actions include construction or alternation of:

  • Public buildings such as city or county offices, jail facilities, public libraries, and school buildings.
  • Public facilities such as water and sewer lines, electrical lines, and roads.
  • Private projects such as subdivisions, shopping centers, other commercial buildings, and industrial facilities.

Nonproject actions

These are agency decisions on policies, plans, and programs including adopting or amending:

  • Rules, ordinances, or regulations to regulate future projects such as water quality rules, critical area ordinances, and other state and local regulations.
  • Comprehensive plans and zoning codes.
  • Capital budgets.
  • Road and highway plans.

When deciding if a project requires SEPA review, remember that agency action includes not only a license but also an agency decision to fund or undertake a proposal. 

Project-level review at the planning stage

Cities and counties can integrate project-level environmental reviews under SEPA with planning-level decisions for urban infill areas. These provisions are intended to help meet planning objectives that focus on development proposals in existing urban areas while still providing the necessary environmental review under SEPA. These tools include:

  • Minor new construction flexible exemption levels
  • Planned actions
  • Subarea planning for urban centers and transit oriented development
  • Urban infill exemption levels

More information about these options can be found in SEPA's Flexible Tools for Project-level Review.

SEPA process summary

  1. Provide a preapplication conference (optional). Although not included in state SEPA rules, we recommend agencies offer applicants the opportunity to discuss a proposal with staff prior before a permit application or environmental checklist is submitted. The applicant and agency can discuss existing regulations, steps and possible review timeline, and other information an applicant needs to submit a complete application.
  1. Determine whether SEPA is required. Determine whether environmental review is required for the proposal by (1) defining the entire proposal, (2) identifying any agency actions (licenses, permits, etc.), and (3) deciding if the proposal fits one of the categorical exemptions.  If the project does not involve an agency action, or there is an action but the project is exempt, environmental review is not required.
  1. Determine lead agency. If environmental review is required, the "lead agency" is identified. This is the agency responsible for the environmental analysis and procedural steps under SEPA.
  1. Evaluate the proposal. The lead agency must review the environmental checklist and other available information to evaluate a proposal’s likely environmental impacts. The lead agency and applicant may work together to reduce probable impacts by revising the proposal or identifying mitigation measures to be included as permit conditions.
  1. Distribute draft checklist for interagency and tribal government consultation. Often the best opportunity to make changes to a proposal based on environmental impacts occurs before the threshold determination and a Determination of Nonsignificance or Determination of Significance has been issued. 
  1. Assess significance and issue a threshold determination - After evaluating the proposal and identifying mitigation measures, the lead agency must determine whether a proposal would still have significant, adverse environmental impacts. The lead agency issues either a Determination of Nonsignificance (DNS), which may include mitigation conditions. If the proposal is determined to have likely significant adverse environmental impacts, the agency will issue a Determination of Significance / Scoping notice (DS/Scoping) which kicks off the Environmental Impact Statement (EIS) process. The EIS will analyze alternatives and possible mitigation measures to reduce a proposal's environmental impacts.
  1. Use SEPA in decision-making - The agency decision-maker must consider environmental information, along with technical and economic information, when deciding whether to approve a proposal. Decision-makers may use SEPA substantive authority to condition or deny a proposal based on information in the SEPA document and the agency's adopted SEPA policies.