HES Treska is consisted of two dams and hydropower plants, HPP Kozjak and HPP Sveta Petka. HPP Kozjak – the dam and hydro plant are located on Treska River, some 25 km upstream from its inflow into the Vardar River and 16 km downstream from HPP Matka in the vicinity of Skopje, and they represent the first level in the cascade of dams and hydro plants on the Treska River. It is designed and constructed with installed capacity of 80 MW and annual production of 156 GWh.

HPP Sveta Petka is located 12 km downstream of Kozjak and 6 km upstream of Matka. It is designed and constructed with installed capacity of 36,4 MW and annual production of 66 GWh.