Looks historically unprecedented (?). This is a run-of-the-river type dam (relatively small elevation drop between upstream and downstream), but one with an enormous reservoir, with a volume (1.8e10 m³ nominal) larger than e.g. Banqiao (4.9e8 m³) or Mosul (1.1e10 m³). It is/was #48 on Wikipedia's ranking of world's largest water reservoirs.
https://en.wikipedia.org/wiki/Kakhovka_Hydroelectric_Power_P...
https://en.wikipedia.org/wiki/Banqiao_Dam