Mouse River Enhanced Flood Protection Phases MI-6, MI-7, MI-8 and MI-9

U.S. Army Corps of Engineers, St. Paul District
Published June 22, 2023
Expiration date: 7/28/2023

There has been a history of flooding along the Souris River (also referred to as the Mouse River) in northcentral North Dakota. In 2011, the flood of record occurred in the Souris River Basin, and caused more than $1 billion in damages to homes, businesses, public facilities, agriculture, and infrastructure along the entire length of the Souris River.

The Souris River Joint Board (SRJB; the “requester”) is pursuing a plan to reduce future flood risks throughout the U.S. portions of the Souris River Basin by constructing a series of new levees, floodwalls, and other flood risk-reduction features. This plan has become known locally as the Mouse River Enhanced Flood Protection Project (MREFPP). The MREFPP would be constructed and permitted in a number of stages over the course of multiple decades, depending on available funding. Ultimately, at completion of construction, the MREFPP would provide flood risk reduction to 27,400 cubic feet per second (cfs), flows equivalent to those experienced during the 2011 flood.

Construction of the MREFPP would require alterations to a number of U.S. Army Corps of Engineers (USACE) flood risk-reduction projects, collectively referred to as the Souris River Basin Project. The SRJB submitted a letter to the USACE to initiate the process for obtaining approval under Section 14 of the Rivers and Harbors Act of 1899 (33 United States Code (USC) 408 (hereafter referred to as Section 408) to allow alterations to existing USACE projects in the Souris River Basin. USACE may issue Section 408 permission to alter a USACE project if it is determined that the modifications are not injurious to the public interest and will not impair the usefulness of the project. The proposed alterations and modifications would further reduce the risks for future flood events for communities along the river. This document supplements previous environmental and other compliance reviews outlined in the MREFPP Programmatic Environmental Impact Statement (PEIS) and adds more specificity to Milestone 2 – the South Minot System (Phases MI-6, MI-7, MI-8, and MI-9) of the MREFPP.

Please note: The Supplemental Environmental Assessment (SEA) includes Appendix 1 and Appendix 2, both of which are available upon request.  Please see the Public Notice for contact information to request these appendices, or for submitting comments on the SEA.