Flood prevention official Zoran Cavlovic told Hina on Wednesday the Sava was at its lowest level since 1878 because there had been no significant precipitations in the past 20 months.
According to the national weather service, no major rainfall is expected in the next ten days. It said this summer was also characterised by long term drought and four heat waves, the last of which is currently under way.
On Friday and Saturday, the highest temperature in most regions will be between 35 and 40 degree Celsius, while on Monday it is expected to drop to a maximum 30.
Production in hydroelectric plants will be 11 per cent below plan and down about 25 per cent from years with average hydrological conditions, HEP told Hina, adding that the market would have to buy 1.5 terawatt hours in additional electricity.