“Over the past century, dams made in the West have become more mismatched with their ambient climate. The Hoover Dam, for instance, was designed based on a 30-year period that had markedly higher precipitation levels than today. As a result of a decade of drought, the dam is now operating at only 30 percent of its capacity, said Matthews, and new mechanisms have been added to cope with the lower water levels.”
World’s Dams Unprepared for Climate Change Conditions: Scientific American