Floating debris accumulation in storage reservoirs of three dam sites in the river Drina catchment area in Serbia have been causing difficulties in operations and occasional loss of electricity. In the previous research it was suggested that the origin of floating debris could be related to landfills near the riverbanks. This paper attempts to strengthen the apparent connection between landfills and floating debris. As a first step, an inventory of landfills in the Drina River catchment area was assembled. It was found that all municipal landfills in the catchment area are uncontrolled, with mixed, partly hazardous waste. Most of the landfills were located at the riverbanks or in the floodplain. Much of the wastes in contact with the surface water became floating debris. The landfills identified as potential sources of floating debris were potentially the sources of water pollution and could have a profound impact on the river environment. It appears that the most affected water body is the last downstream reservoir of the Drina River due to a cumulative effect of the upstream landfill activities, as well as due to other anthropogenic pressures. The international watershed of the Drina River includes three countries: Bosnia and Herzegovina, Montenegro, and Serbia, thus the problem of floating debris is a regional ecological problem. In order to address this problem and find solutions, it was proposed to identify floating debris as a common and urgent problem in this area, and furthermore to develop a comprehensive plan for future actions.