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SR 520 - Environmental and Planning Documents

This page and its subpages contain the environmental impact statements and other planning documents created for the SR 520 reconstruction program.

What is an environmental impact statement? 

Under the requirements of the National Environmental Policy Act (NEPA) and the State Environmental Policy Act (SEPA), an environmental impact statement (EIS) is a document that discloses potential effects from a proposed project. An EIS describes the purpose and need of the project and proposed plans for its construction. It also provides comprehensive analysis about project operations and environmental effects.

View documents by geographic area

Seattle and the floating bridge (I-5 to Medina)
I-5 to Lake Washington (Seattle-specific process)
Eastside (Medina to SR 202)
Pontoon construction (Aberdeen, WA)
Program-wide 2006 Draft EIS ("I-5 to I-405 draft Environmental Impact Statement")
Other environmental documents