An expansive, multidecadal agricultural dataset is now available from Purdue University. The Southeast Purdue Agricultural Center (SEPAC) drainage research data are from a long-term subsurface drainage project that was conducted at SEPAC in Jennings County, Indiana, from 1984 to 2020. SEPAC is one of eight Purdue Agricultural Centers (PACs) across Indiana that researchers use to conduct applied field crop and animal research. This project was funded in part by the Agricultural Research and Graduate Education (ARGE) office at Purdue and the USDA National Institute of Food and Agriculture.