Slovenia's biggest energy group HSE, the owner of companies operating hydro plants on the Soča and Drava, told the STA that the river stage on both rivers has been lower than the long-term average this year.

"Because of lower river stages the production of electricity was also lower," HSE noted. While production at HSE's plants on the two rivers dropped by a third, the holding offset the losses with higher production at the coal-fired TEŠ power plant.

Gen energija, which operates hydro power plants on the Sava, meanwhile told the STA that the river stage was also lower than the average.

The flow at the Krško power plant stood at 55 cubic metres per second on average last week. In the past five years, it was only lower in 2012, when the August average dropped to 53 m3/s.

The company added that the rated output of hydro stations was reached at 500 m3/s, with the combined output of stations under the Savske elektrarne Ljubljana at 19 megawatts or at a third of the rated output.

The combined output of stations at the lower Sava currently stands at 20MW or less than a tenth of the rated output.