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SR 520 - Environmental documents

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


What is an environmental impact statement?

An environmental impact statement (EIS) is a document that discloses potential effects from a proposed project under the requirements of the National Environmental Policy Act (NEPA) and the State Environmental Policy Act (SEPA). 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