Litter can be a personal issue. For some, the shock of seeing sea lions munching on plastic bags spurs the urge to volunteer for beach clean-ups. For others, the importance of keeping our water clean hits home when family members get sick after a swim at a contaminated beach. But for many, soda bottles, food wrappers, and cigarette butts are just bits of muck that hit the street and wash away, forgotten. That waste doesn't just disappear, though, and it can be costly to clean up. As revealed in a new report produced on behalf of the Natural Resources Defense Council by Kier Associates, California cities, towns, and tax payers, are shouldering $428 million per year in costs to stop litter from becoming pollution that harms the environment, tourism and other economic activity.