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Long-Range Plan Draft Supplemental Environmental Impact Statement

On June 13, 2014, Sound Transit released the Long-Range Plan Update Draft Supplemental Environmental Impact Statement (Draft SEIS) for public comment in accordance with the Washington State Environmental Policy Act (SEPA). Analysis and public feedback will help the Sound Transit Board determine how the agency's Long-Range Plan should be updated. In addition, it may also help inform the Board where mass transit should expand after the current set of projects are complete in 2023, funding for which was approved by voters in 2008.    

The comment period on the Draft SEIS concluded on July 28, 2014. Comments provided on the DSEIS this summer will help the Sound Transit Board identify future transit expansions after the light rail extensions are complete in 2023. All comments will be responded to in the Final SEIS, expected in Fall 2014.

Sound Transit hosted six open house/public hearings in July 2014.

Copies of the Draft SEIS: Hard copies of the Draft SEIS are available for $20.00 and hard copies of the separately bound Transportation Technical Report (Appendix K) are available for $15. The Executive Summary and a CD including the Draft SEIS, the Transportation Technical Report, and all other appendices are available at no charge. Please contact Karin Ertl for copies at 206/398-5360 or


Documents in .pdf format require the free Adobe Acrobat Reader to view.


Cover Letter, Fact Sheet, Table of Contents and Acronyms (577 KB)

Executive Summary (3.3MB)

Chapter 1: Purpose and Need (273 KB)

Chapter 2: Alternatives Considered  (949 KB)

Chapter 3: Transportation Impacts and Mitigation (1 MB)

Chapter 4: Environmental Impacts and Mitigation (6.5 MB)

References, Glossary, List of Preparers, and Distribution List (240 KB)


Appendix A: Current Plan and Potential Plan Modifications Alternatives: Corridors and Representative Projects/Programs/Policies  (264 KB)

Appendix B: Agency Coordination and Public Involvement (1.1 MB)

Appendix C: Water Resource Inventory Areas and Category 5 Listings (1.2 MB)

Appendix D: Regionally Important Ecosystem Resources (134 KB)

Appendix E: High Risk Hazardous Materials Sites in the Plan Area (278 KB)

Appendix F: Consistency with Land Use Plans, Policies, and Legislation (400 KB)

Appendix G: Parks and Recreation Facilities in the Plan Area (604 KB)

Appendix H: NRHP-listed Architectural Historic Properties and Districts in the Plan Area (526 KB)

Appendix I: Transportation Projects Considered for Cumulative Impacts Analysis (252 KB)

Appendix J: Environmental Justice Study (448 KB)

Appendix K: Transportation Technical Report (3 MB) 

*Printed versions are available on request for the cost of reproduction.