National and local environmental groups want to see the Mississippi River Gulf Outlet in Louisiana closed and its ecology restored. Critics of the 76-mile-long waterway, known as "Mr. Go," contend that it acted as a funnel for Hurricane Katrina's surge last year.

In an appropriations bill enacted in June, Congress directed the Corps of Engineers to issue an interim report by Dec. 15, laying out a plan to deauthorize MRGO for deep-draft shipping. A Corps spokesman says the report is under review. The legislation also provides $3.3 million for the report.

Environmental Defense, the Coalition to Restore Coastal Louisiana and other groups recommend such steps as cutting or narrowing MRGO with fills, turning the waterway into a series of lakes.