The reservoir was created in 1959 after a dam with a power plant was built in the Vltava valley between 1952 and 1959. This measure was intended to protect the region, especially the downstream towns of České Budějovice (Bohemian Budweis) and Prague, from flooding. Even then, the lake was nicknamed Jihočeské moře (South Bohemian Sea) or Šumavské moře (Bohemian Forest Sea).