The U.S. Army Corps of Engineers, Walla Walla District (USACE), in partnership with the Confederated Tribes of the Umatilla Indian Reservation (non-federal sponsor), is conducting an aquatic ecosystem restoration study under the authority of Section 206 of the Water Resources Development Act (WRDA) of 1996 (Public Law 104-303), as amended, and Section 165(a) of WRDA 2020. The study is focused on improving fish passage and water quality conditions within the Mill Creek Flood Control Project (MCFCP) in Walla Walla, Washington.

The purpose of the study is to identify and address physical and thermal barriers to fish migration that affect ESA-listed mid-Columbia River steelhead and bull trout, as well as tribally reintroduced Chinook salmon. The proposed action area begins four grade control structures downstream of the Division Works and extends across 63 structures, covering approximately 0.8 miles. Building on ongoing and planned fish passage improvements within the MCFCP, the study seeks to improve connectivity to approximately 26 miles of upstream spawning and rearing habitat.

The study includes coordination with key stakeholders, including local and state agencies, tribal nations, and conservation organizations. It will also evaluate past USACE and sponsor-led projects within the Mill Creek system and identify opportunities for further ecosystem improvements, while considering flood risk management constraints.

Public Comment and Review:

The documents associated with this study include the draft Integrated Feasibility Report and Environmental Assessment (IFR/EA), the draft Finding of No Significant Impact (FONSI), and associated appendices. These documents can be electronically accessed within the “Links” section on the right-hand side of this webpage.

USACE is soliciting public comments and review on the study's findings.

Comments will be accepted from Apr. 15 through May 20, 2026. 

A virtual Q&A will be held on May 13th, 2026. Virtual meeting links will be published here at a later date.

How can I comment?

There are several ways that you can provide input on this study.

You can submit a comment through the NEPA Online Comment Form, https://www.nww.usace.army.mil/EnvironmentalComplianceComment/ or by emailing NEPANWW@usace.army.mil, inserting “Umatilla Mill Creek Aquatic Ecosystem Restoration” in the subject line.

You may submit written comments via U.S. Mail to:

Comments need to be submitted or postmarked no later than May 20, 2026 for consideration.  All comments submitted will be considered and become part of the public record.

For more information on the public meetings or about this study, please contact Austen Whelan at Austen.P.Whelan@usace.army.mil.