French authorities were alerted to cocaine that washed up on a beach along the English Channel in late February. But it wasn't just an amount that could've fallen out of someone's bag, it was 850 kilograms -- or nearly two tons -- of cocaine.

Steve Rolles of the U.K.-based Transform Drug Policy Foundation says it's not uncommon for large amounts of drugs to wash up on shore and explains why trace amounts of cocaine showed up in British wastewater samples.