However, the Vltava River wasn't always like this. During the period of communist rule and the Velvet Revolution, the Vltava was one of the most polluted rivers in europe. It was used as a dump by heavy industry, and chemicals like PCBs were poured directly into the river. In addition, because the water treatment plants for sewage were ineffective, the river had an unpleasant smell.
Beginning in the 1990's, the decline of heavy industry and major upgrades in water treatment improved the water quality immensely. Pollution levels have dropped to a tenth of pre-1989 levels and fish previously unable to survive, like trout and salmon, are making a comeback. Combined with the revitalization of the waterfront, the Vltava River is once again a beautiful place.