While floatable debris in the open waters of Long Island Sound is less concentrated than in the neighboring New York-New Jersey Harbor estuary and in western Long Island Sound embayments, it is present in great enough quantities to mar the aesthetic enjoyment of the Sound. These slicks can wash ashore fouling beaches and the coastline. Floatable debris is also a nuisance and hazard for boaters. Floating lines can foul a boat's propellers, and sheets of plastic or plastic bags can block an engine's cooling water intake, resulting in the engine overheating. Collisions with larger, heavier floatable debris can cause hull or propeller damage to boats.
Floatable debris can harm wildlife when it is ingested or when organisms become entangled in it.
Ingestion can cause suffocation or starvation. Undigested plastic pellets can stay in the stomachs of wildlife, leaving no space for real food. Floatable debris can have a particularly detrimental effect on endangered species, where the loss of an individual is devastating to a small population. The ultimate source of floatable debris is people who litter and improperly dispose of their waste. Litter anywhere in the Sound's drainage basin can ultimately enter the Sound.