Army Corps of Engineers: Determinations That Projects Do Not Need Environmental Mitigation Should Be Clarified

The Army Corps of Engineers manages water infrastructure projects, such as levees to control flooding. But some projects can harm the environment, including fish and wildlife.

The Corps must report to Congress on its plans to mitigate environmental harms—or its determinations that mitigation isn't needed.

This Q&A reviews the Corps' plans and determinations that mitigation wasn't needed. For 2020-2025, the Corps submitted plans for 30% of its projects. But the Corps didn't clearly document why mitigation wasn't needed for the other projects.

We recommended it do so to keep Congress informed about projects' environmental impacts.

Army Corps Flood Control Project in New Orleans

Aerial view of a levee spanning a waterway, with an opening in the center.

Through its Civil Works program, the U.S. Army Corps of Engineers plans, constructs, and maintains water resources projects around the country. For any Civil Works projects submitted to Congress for authorization, federal statute requires the Corps to report its plans for environmental mitigation—that is, actions to avoid, minimize, or compensate for any expected losses to fish and wildlife and damage to ecological resources resulting from its projects. If the Corps determines no mitigation is necessary, it is required to report that determination.

Of the 74 Civil Works projects submitted to Congress for authorization during calendar years 2020–2025, the Corps determined that mitigation plans were needed for 22 projects and not needed for 52 projects. For the 22 projects with mitigation plans, GAO found that the plans generally included selected components from the 2008 Rule, “Compensatory Mitigation for Losses of Aquatic Resources.” For the 52 projects that the Corps determined did not need mitigation plans, GAO found that reports submitted to Congress for project authorization, and supporting feasibility reports, generally did not clearly document the Corps’s determination that no mitigation was needed and why.