This dataset contains the contours, in feet, of the potentiometric-surface, spring 2018, Mississippi River Valley alluvial (MRVA) aquifer. The contours are referenced to the North American Vertical Datum of 1988 (NAVD 88). The contours were derived from most of the available groundwater-altitude data from wells and surface-water-altitude data from streamgages, measured in for spring 2018. The potentiometric contours ranged from 10 to 340 feet (3 to 104 meters) above NAVD 88. The regional direction of groundwater flow was generally towards the south-southwest, except in areas of groundwater-altitude depressions, where groundwater flows into the depressions, and near rivers, where groundwater flow generally parallels the flow in the rivers.