Kozjak Hydro Power Plant is a large hydroelectric power plant on the river Treska which creates an artificial lake Kozjak, the largest in North Macedonia.

The impounded reservoir is stretched along municipalities of Želino, Brvenica and Makedonski Brod.

The primary purpose of the dam is flood control but it also serves for power generation.

The lake is 32 km (20 mi) long, with maximum depth of 130 m (430 ft).

The reservoir started filling in May 2003, and the two power generators finally operated in July and September 2004.