During the July 2021 European floods approximately 8 million pieces of plastic dairy packaging were flushed from a severely damaged dairy processing facility located at the Vesdre river in Belgium. Some of these dairy packaging 'buttertubs' were ultimately flushed into the Meuse river and counted on riverbanks along the Dutch Meuse between July 2021 and July 2023. In addition to recording when and where they were found, some were collected for analysis on their development of mass over the two years between July 2021 - July 2023. The article attached to this dataset is called "Flood-induced buttertub spill reveals riverine plastic transport dynamics" and has the DOI 10.1186/s12302-024-00962-1. Dataset 1 contains the locations where buttertubs were found over the two years, with the location coordinates and sampled area of riverbank. Dataset 2 contains the mass analysis of the collected buttertubs before and after they were cleaned and dried. Dataset 3 contains pictures of the buttertubs analyzed for their mass prior to cleaning.