Lake Tahoe, USA

Lake Tahoe has been inundated by tourists and people who have purchased second homes in the area. This means car traffic around the lake as skyrocketed, which affects the quality of the water, according to The League To Save Lake Tahoe’s website. The lake is famous for its pristine blue water, but too many people and too much traffic can increase the sediment pollution into the lake, according to Fodor’s.