WARSAW — The rain has stopped, at last, but the danger persists in flood-ravaged Serbia, where a lake of water is pushing its way down the Sava River, toward the Danube, threatening the capital, Belgrade, and the power plant southwest of the city that provides half of the nation’s electricity.

Workers already had been struggling around the clock to build a barricade of sandbags to save the coal-fired Nikola Tesla power plant in the hard-hit town of Obrenovac, along the Sava. So far, they have been successful.

But the storm surge, which was subsiding in eastern Bosnia and Herzegovina and also western Serbia, was expected to edge into the Belgrade area late Monday and crest sometime Wednesday.