When the Associated Press reported in early December 2015 that the waters surrounding Rio de Janeiro had flunked a majority of clean-water tests, potentially putting Olympic athletes in danger during the 2016 games, not many were surprised. “There is sewage flowing directly into the bay there, most surfers avoid the area,” said Mara Dias, of Surfrider Foundation, a group dedicated to keeping America’s surf breaks clean. But, don’t think that it's just Rio that struggles with keeping water clean and safe, the issue touches all corners of the globe. Here in the United States, a myriad of groups are constantly battling corporations, utilities, and cities to keep the waterways we play in clean. But before you suit up and venture off for your next dip, here are some popular spots you'll want to avoid.