Transmission Programmatic Environmental Impact Statement (EIS)

In 2023, the Legislature asked us to study the environmental effects of building, upgrading, and operating electrical transmission facilities with a nominal voltage of 230 kilovolts or greater in Washington. This page lays out: (1) the background that led to this study; (2) details about the study's goals, areas studied, requirements for environmental review, and contributors to the study; and (3) explanation of the process used and presentation of the individual chapters with links to the draft programmatic environmental impact statement (PEIS) for electrical transmission facilities.

Background for the Programmatic EIS

Released on October 7, 2025, this Programmatic Environmental Impact Statement (EIS) generally evaluates direct, indirect, and cumulative adverse environmental impacts associated with the building, operating, maintaining, upgrading, and modifying of high-voltage transmission facility developments. We prepared the Programmatic EIS in accordance with the State Environmental Policy Act (SEPA) as outlined in Chapter 197-11 WAC, EFSEC's authorities defined in Chapter 80.50 RCW, and legislative directives codified in RCW 43.21C.405. It includes an analysis of the potential impacts on the natural and built environments mentioned in RCW 43.21C.405(3), WAC 197-11-444, and WAC 463-60-535.

This Programmatic EIS is intended for use in future planning and development of transmission facilities and during subsequent project-level environmental review of proposed transmission projects 230 kV or greater. It does not propose, evaluate or approve a specific project or project-specific application; and it does not eliminate the requirement for project-level SEPA environmental review. 

The Final Programmatic EIS identifies recommended mitigation measures to address potentially significant adverse environmental impacts from transmission facilities. Per RCW 43.21C.408, SEPA lead agencies must consider the document during their environmental review of transmission facilities; and it is structured so that future transmission projects that follow the recommendations developed within are considered to have mitigated for all probable significant adverse environmental impacts addressed in the Programmatic EIS.

This Programmatic EIS adds to other programmatic EISs that the Washington Department of Ecology released for onshore wind energy, utility-scale solar energy, and green hydrogen production and storage facilities (link, webpage) in June 2025.

Goals of the Programmatic EIS

This Programmatic EIS analyzes the environmental effects of high-voltage electrical transmission facilities but doesn't review any specific facility. Relevant SEPA lead agencies will need to perform their own SEPA environmental reviews for specific proposed transmission facilities.  

Our goals for this Programmatic EIS were to:

  • Broadly assess environmental impacts common to these facilities
  • Provide technical guidance to developers and SEPA lead agencies
  • Standardize, facilitate, and expedite environmental review
  • Support informed decision-making
  • Identify mitigation strategies to reduce adverse environmental impacts
  • Initiate public and stakeholder engagement

Study Scope

The geographic scope, or study area, of this Programmatic EIS includes areas throughout Washington where developers are likely to build transmission facilities. Tribal lands and underwater cables were identified as beyond the regulatory and technical scope of the Programmatic EIS and were not included in the final analysis. For details, see Section 1.5.1 Geographic Scope in Chapter 1 of the Programmatic EIS (link, 2 KB pdf).

The following resource areas were evaluated:

  • Earth resources
  • Transportation
  • Air quality, including greenhouse gases
  • Public service & utilities
  • Water resources
  • Visual quality
  • Vegetation
  • Noise & vibration
  • Habitat, wildlife, & fish
  • Recreation
  • Energy & natural resources
  • Historical & cultural resources, including Tribal rights, interests & resources
  • Public health & safety
  • Socioeconomics, environmental justice & overburdened communities
  • Land & shoreline use
  

Requirements for environmental review

This Programmatic EIS includes three categories of requirements for project-level environmental review:

  • General measures
  • Avoidance criteria
  • Mitigation measures

For details, see the introduction to Chapter 3 of the Programmatic EIS (link, 8.5 MB pdf) on the affected environment, significant impacts, and mitigation.

Project-specific applications would include details about the precise location and site-specific conditions. For most environmental resources, the Programmatic EIS provides sensitivity maps throughout Chapter 3, which are explained in the chapter's introduction (see Section 3.1.6 Environmental sensitivity map). Using these maps can make environmental planning more informative and efficient.  

Participants

We prepared this Programmatic EIS with the support of WSP USA, Inc. and contributions from the following local, state and federal agencies:

  • Benton County
  • Washington Department of Ecology
  • Bonneville Power Administration
  • Washington Department of Natural Resources
  • Grant County
  • Washington Department of Transportation
  • Washington Department of Fish & Wildlife
  • Washington Office of the Attorney General
  • Washington Office for Regulatory Innovation & Assistance
  • Washington Utilities & Transportation Commission
  • Washington Department of Archaeology & Historic Preservation
  • U.S. Department of Defense
  • Washington Department of Commerce
  

Process

In June 2024, EFSEC took the first step in developing the Programmatic EIS. It published the SEPA Scoping Document (link, 890 KB pdf) and opened a 30-day public comment period from June 28, 2024, until July 28, 2024. As part of this process, EFSEC also held two virtual public comment meetings during this period.

On March 31, 2025, EFSEC released the Draft Programmatic EIS. EFSEC staff made a public presentation of the document on April 8 and held two public comment meetings in April 2025. It took public comments until May 15, 2025.

On October 7, 2025, we released the Final Programmatic EIS, and a full list of the chapters within this document follows: