I-90 Exit 406 Interchange Modification Study and Environmental Assessment

Environmental Assessment Complete

Upon completion of the public comment period in October 2019, SDDOT and FHWA reviewed the Environmental Assessment (EA) along with the comments received for a determination on completion of the environmental review process. Through this review, FHWA and SDDOT made a Finding of No Significant Impact (FONSI) determination. The FONSI determination means that the EA adequately discusses the need, purpose, alternatives, environmental resources, and impacts of the Project. The FONSI includes a review of environmental commitments and mitigation measures, along with an Appendix of the comments received and responses to comments.

Project Overview

The South Dakota Department of Transportation (SDDOT), City of Brandon, Sioux Falls Metropolitan Planning Organization (MPO), and Federal Highway Administration (FHWA), have identified a need to revisit and further study the originally proposed alternatives and other potential improvements to the 1-90 Exit 406 interchange. The study includes an Interchange Modification Justification Report (IMJR) and associated environmental investigation.

Study Overview



Steve Gramm
SDDOT Project Manager

Ben White
Consultant Project Manager


Send Us Your Comments

Public Comment Summaries


Public Information Meeting #3

As part of the comment period, the project team hosted a public meeting on the evening of Wednesday, September 18th in Brandon. Details about the meeting, including the formal public advertisement are as follows:

Environmental Assessment Documents


Public Information Meeting #2

Build Alternative Figures

The following alternatives were carried forward for further evaluation in the development of a proposed action for this project.


Public Information Meeting #1