Regulating Works: Supplemental Environmental Impact Statement (SEIS)

The U.S. Army Corps of Engineers St. Louis District is responsible for providing a safe and dependable navigation channel, 9 feet deep and not less than 300 feet wide, with additional width in the bends as required, on the Middle Mississippi River (MMR). The MMR is defined as that portion of the Mississippi River that lies between the confluences of the Ohio and Missouri rivers. This is achieved through the authorized Regulating Works Project.

The Regulating Works Project consists of bank stabilization and sediment management to ensure adequate navigation depth and width. Project improvements are achieved through the construction of river training structures, revetment, rock removal, and construction dredging. The Regulating Works Project is maintained through dredging and any needed maintenance to already constructed features. The long-term goal of the Regulating Works Project, as authorized by Congress, is to alleviate or eliminate the amount of annual maintenance dredging and the occurrence of vessel accidents through the construction of river training structures to provide a sustainable navigation channel and reduce federal expenditures. Since the 1970s various environmental laws, regulations, and policies have resulted in considering the environment in the design and construction of the Regulating Works Project.

The National Environmental Policy Act (NEPA) requires federal agencies to analyze the impacts of their actions on the environment and disclose the impacts in Environmental Assessments (EAs) or Environmental Impact Statements (EISs). The EIS that analyzed the impacts of the Regulating Works Project was prepared in 1976. The 1976 EIS was recently reviewed by the District to determine whether or not the document should be supplemented. The District concluded that the Regulating Works Project has not substantially changed since 1976 but that there are significant new circumstances and information on the potential impacts of the Regulating Works Project on the resources, ecosystem and human environment to warrant the preparation of a Supplemental EIS (SEIS).

The Final SEIS was available for public review for 45 days from May 12 to June 27, 2017. The Record of Decision was signed on August 31, 2017.




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U.S. Army Corps of Engineers St. Louis District
Regional Planning and Environment Division North
1222 Spruce St.
St. Louis, MO 63103-2833