The MRRRI Act establishes a federal program to protect and restore the Mississippi River ecosystem across nine states (Arkansas, Illinois, Iowa, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Tennessee, and Wisconsin) through a new Mississippi River National Program Office within the EPA. The bill authorizes funding for restoration projects in five key areas: water quality improvement, community flood resilience, fish and wildlife habitat protection, invasive species prevention, and scientific monitoring, with eligible projects including wetland restoration, dam removal, land conservation, floodplain restoration, and invasive species removal. The MRRRI Director must develop measurable success goals within one year and a comprehensive action plan within two years—updated every five years—with mandatory input from federal agencies, tribes, states, and the public. The legislation requires at least 5 percent of funding to support tribal projects through the Bureau of Indian Affairs and establishes three research centers within the U.S. Geological Survey to guide restoration science and identify research priorities. While the bill does not specify total funding amounts, it authorizes money transfers to federal and non-federal entities, with non-federal partners required to contribute 80 percent cost-sharing (100 percent for tribal governments).