The 1879 law that established the MRC calls for its membership to consist of three U.S. Army Corps of Engineers officers, one member of the National Oceanic and Atmospheric Administration (formerly the Coast and Geodetic Survey), and three civilians, two of whom must be civil engineers. Each member of the MRC is nominated and appointed by the United States President. They are vetted by the Senate. The commission president also serves as commanding officer of the Mississippi Valley Division. 

The other military members typically serve as the commanding generals of the Corps of Engineers’ division offices responsible for managing the key contributors of water to the Mississippi River, such as the Ohio, Missouri, Arkansas, White and Red rivers.

The civilian members, in turn, bring representation from the world’s most innovative engineering and business pools of talent - the United States private sector.  

Representation from NOAA, the science agency of the Department of Commerce, equips the commission with accurate weather forecasts, objective analyses of climate changes, unmatched mastery of marine sciences and state of the art LIDAR technology.

The general duties of the MRC include the recommendation of policy and work flood control, navigation, and environmental projects on the Mississippi River, programs, the study of and reporting on the necessity for modifications to and conducting semiannual inspection trips and public hearings at various locations along the river. The work of the MRC is directed by its president and carried out by Army engineer districts from the watershed.