Lake Ormož (Slovene and Croatian: Ormoško jezero) is a reservoir on the Drava River in north-eastern Slovenia and north-western Croatia, forming a part of the border between the two countries.

It was named after the nearby Slovenian town of Ormož on the left bank of the Drava River, just next to its northern end, and has an area of approximately 3 km2.

[1] The reservoir was constructed in 1975, when both Slovenia and Croatia were part of Yugoslavia, to serve the Varaždin Hydroelectric Power Plant.

The dam and the power plant are on the Croatian side of the border and represent the southern end of Lake Ormož.

[1] After the sugar factory was closed, the six retention basins became a marsh in a matter of years, eventually being protected as a nature reserve on a national level in 2017.