The U.S. Army Corps of Engineers - Walla Walla District (Corps) is preparing the Mill Creek Flood Control Project Operations and Maintenance Supplemental Environmental Impact Statement (SEIS).

The Corps is preparing this SEIS to update the National Environmental Policy Act compliance for operations and maintenance of the Mill Creek Project in Walla Walla, Washington. The SEIS is needed because changes in required operations and maintenance activities and new environmental conditions within the project area have occurred since the original 1975 project Final Environmental Impact Statement (FEIS) was prepared by the Corps for the operation, maintenance, and improvement of the federally managed portion of the Project.

The Corps proposes to operate and maintain the Mill Creek Project in accordance with its authorized purposes of flood risk management and recreation, while minimizing impacts to the environment, in particular impacts to Endangered Species Act protected fish and associated critical habitats. The SEIS will identify and evaluate current O&M actions that may not have been adequately addressed in the 1975 FEIS or have been implemented since completion of the 1975 FEIS, and actions that are proposed for the future. It will also identify and evaluate operational and structural measures the Corps has proposed to improve fish passage through the Mill Creek Project.

A public scoping period was conducted May 12 through June 12, 2017, including a public meeting held May 24, 2017, in Walla Walla, Washington. All information and comments submitted during the scoping period were considered in the development of the draft SEIS and included in the permanent public record.

The draft SEIS 46-day public comment period was conducted June 8 through July 23, 2018. The Corps’ draft SEIS and appendices are available below under “Links" on this webpage, along with the Corps' Notice of Intent in the Federal Register, Mill Creek Project’s 1975 FEIS and a topic-related fact sheets. All information and comments received during the draft SEIS comment period will be considered in the development of the final SEIS and included in the permanent public record. The District will keep the public informed by updating this webpage and distributing a news release once the SEIS is finalized.