The Midwest Regional Carbon Sequestration Partnership (MRCSP) was founded in 2003 as part of the U.S. Department of Energy?s (DOE?s) Regional Carbon Sequestration Partnership initiative. Since its founding, MRCSP has made significant strides toward making CCUS a viable option for states in the region. The public/private consortium, funded through the DOE Regional Carbon Sequestration Initiative, brings together nearly 40 industry partners and 10 states. Battelle, as the project lead, oversees research, development and operations and coordinates activities among the partners. The incremental, phased approach has built a valuable knowledge base for the industry and paved the way for commercial-scale adoption of CCUS technologies. From 2008 to 2020, MRCSP Phase III focused on the development of large-scale injection projects. This report is part of a series of reports prepared under the Midwestern Regional Carbon Sequestration Partnership (MRCSP) Phase III (Development Phase). These reports summarize and detail the findings of the work conducted under the Phase III project. MRCSP monitoring efforts began in February 2013, with an overarching goal of monitoring at least 1 million metric tons (MT) of net CO<
sub>
2<
/sub>
stored at a CO<
sub>
2<
/sub>
-EOR complex in northern Michigan. This report highlights the mass balance accounting of injection, production and recycling activities at ten CO<
sub>
2<
/sub>
-EOR reefs. The reefs that were monitored for CO<
sub>
2<
/sub>
-EOR operations include a late-stage depleted reef, eight active CO<
sub>
2<
/sub>
-EOR reefs and two new reefs added to the CO<
sub>
2<
/sub>
-EOR complex where a CO<
sub>
2<
/sub>
flood was initiated.