Marine debris is more than just a litter problem; it kills marine wildlife, hurts the Bay's aesthetic qualities, and is expensive for coastal communities to clean up. Over 4000 tons of trash are collected from Los Angeles County beaches annually, at a cost of $3.6 million to Santa Monica Bay communities in fiscal year 1988-89 alone. While much of it is left by the approximately 51 million beachgoers who visit the Bay each year, much is also carried there through storm drains.

Debris includes plant remains such as trees, kelp, and grass clippings as well as the shells, bones, and carcasses of animals. It also includes aesthetic nuisances such as paper, plastic, and wood, as well as fishing line and nets. More dangerous items include glass and metal objects which pose physical hazards on the beaches and on the bottom of the Bay, and some plastic items which can harm or kill marine life if they are eaten or if animals become entangled in them.