In this data release, we provide the data used to compute total annual phosphorus loads from tributaries and direct drainages to the Great Lakes during 2012-18 using the model load ratio approach and the unit area load approach and the resulting annual loads for 2012–18. This data release consists of: (1) measured loads at 24 sites, computed using the surrogate regression approach (Robertson et al., 2018; Koltun, 2020) that were monitored as part of the Great Lakes Restoration Initiative project, (2) estimated annual loads at point source facilities throughout the Great Lakes Basin obtained from the U.S. Environmental Protection Agency and state agencies, (3) loads subdivided into nonpoint and point source contributions, (4) extrapolation factors for each basin (nonpoint model load ratios, nonpoint yields, point source delivery factors), and (5) estimated annual loads for each tributary and direct drainage area to the Great Lakes during 2012–18. This data release consists of three tab delimited files: (1) ReferenceSite.txt, which contains all of the information (site data and phosphorus loads from SPARROW (Robertson and Saad, 2019) and measured during 2012–18 for the 24 reference (extrapolation sites) used in this study, (2) PointSource.txt, which contains all of the measured or extrapolated point source information for wastewater treatment plants in the Great Lake Basin for 2012–18; and (3) ExtrapolatedLoads.txt, which contains all of the nonpoint model load ratios, point source delivery ratios, measured wastewater treatment plant loads, and resulting annual loads for each tributary and direct drainage area in the Great Lakes Basin for the long-term average and 2012–18.