Several power plants along the long river use the water to cool their reactors, but as the water recedes, nuclear power plants in both Romania and Hungary have reduced capacity, and hydroelectric plants in Serbia have been affected.
The Romanian government has asked the public to save electricity so the country does not have to increase energy imports and the use of natural gas.
In Serbia, temperatures are expected to rise towards 40 degrees this week, and the heat could last for almost two weeks.
In Bezdan, near the border with Croatia and Hungary, the lowest water levels in more than 50 years have already been measured, and if they fall even further, the water shortage could threaten agricultural supply.
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