When complete, it is to cover a surface area of 19 km2 (7.3 sq mi), making it one of the biggest artificial lakes in the country.

However, the water volume of Geiseltalsee is almost three times larger at 0.423 cubic kilometres (0.101 cu mi).

The largest reservoir (i.e. an artificial lake created via a dam) in Germany by surface area is Forggensee in Bavaria with a surface area of 15.2 square kilometres (5.9 sq mi) and a maximum water volume of 0.168 cubic kilometres (0.040 cu mi).

However, this lake is reduced to a "rump" of 3.2 square kilometres (1.2 sq mi) surface area in winter.

Flooding started in 2019[2][3] but had to be interrupted several times due to low water levels in the nearby Spree River.