The idea of ​​a tunnel that will divert some of the water from the river Vardar into the river Treska, i.e. from the location of Tenovo to the reservoir of Kozjak, is more than 50 years old. Based on the first Study regarding this idea, developed by a Norwegian consulting company, technical documentation was prepared only regarding the Tenovo-Kozjak Tunnel, which provides energy indicators and some financial analysis at today’s prices and in North Macedonia’s power system completeness. This endeavor of building a tunnel would actually divert part of the waters of the river Vardar, instead through the Polog Plain and Vardar River, to move through the river Treska after being used for energy generation in Treska Hydro-system (HS), and flow into the Vardar before Skopje.

In further support of this idea to build a diversion tunnel in order to divert water from the Vardar into the Treska and use it for power generation, is also the completion of Treska Hydro-system. By building Kozjak HPP (2004) and Sveta Petka HPP (2012) with their reservoirs, as well as with the revitalized and upgraded Matka HPP, the water diverted from the river Vardar would be additionally used in these three hydro-power plants, and it would be pumped into the river Vardar at the estuary of the river Treska before Skopje.

The tunnel envisaged to be build from the location of Tenovo (on the Gostivar-Tetovo stretch) to the Kozjak Reservoir is about 14.5 kilometers long, which is the shortest distance to divert part of the waters from Vardar River to Treska River.

Energy Benefits

• Additional power generation of power plants at Treska River of about 110 GWh annual average.
• Higher engaged power of Kozjak HPP due to the increased higher elevation operating time of Kozjak Reservoir.
• Operational work of hydro-power plants on the river Treska in high tariff periods as operational plants in a liberalized electricity market, which means a higher income for the power plant and ESM as an operator.
• Opportunities for additional production in newly built hydro-power plants on the Raven-Kozjak stretch.

Other Benefits (Flood Protection, Needs for Water Supply and Irrigation)

• Avoidance of overflows and floods of the river Vardar into the Polog Valley in periods of high water level, where part of the waters would be diverted to Treska River.
• Additional water for water supply of settlements in the Valley of Polog.
• Flow of the river Vardar regulated in its upper stream and a possibility for irrigation of Polog agricultural region.

 Tunnel Tenovo-Kozjak