STREAM-BORNE FLOATING MISMANAGED WASTE IN A SMALL MIDWESTERN WATERSHED: FOCUS ON FOAM

Streams and storm drain systems link terrestrial roadside litter to rivers and lakes, which can eventually supply floating debris to the global ocean. To better understand this linkage, we evaluated the kinds and quantity of floating mismanaged solid waste being transported in five streams within the Lake Macatawa watershed in the environs of Holland, Michigan. We deployed floating litter booms in the four smallest streams. These consisted of a rip-stop nylon sleeve covering pool noodle floats strung on a wire rope. These were placed diagonally across the stream and anchored to fence posts set into the stream banks. In the largest stream, Paw Paw Creek, we used a Trash Trout Jr., a three-sided cage of chain link fencing mounted on pontoon floats. Collection took place between June 16 and July 12, 2023. Conditions during the collecting period were generally dry so the collection largely represents transport of litter during base flow.

Comparison of local roadside litter with items captured in streams revealed differences in composition. Plastic items exclusive of foam constituted 52.5% of collected roadside litter while expanded plastic foam accounted for an additional 8.1% of the total items collected. In contrast, expanded plastic foam comprised the majority of floating litter items collected at each of the five stream sites, ranging from 56.8% to 82.4% of the items captured. Much of this foam was degraded into fragments. The ability of foam to float and its tendency to break readily into small pieces may account for its high prevalence. The frequent transport of foam under normal flow conditions suggests that it could be a productive focus for efforts to reduce water-borne litter. Fortunately, reasonable substitutes for many foam items are available, increasing the likelihood of success for campaigns aimed at producers, retailers, or consumers to replace foam products or reduce their consumption.