Floodwaters that broke through a dike and submerged villages last week poured back into the swollen Oder River on Sunday, raising levels downstream to record highs and forcing evacuations.
Officials ordered the 17,000 people in the Polish border city of Slubice - just across the water from Frankfurt an der Oder - to evacuate again for fear the river would break through the dike.To the north, about 15,000 people on the German side were told to be ready to leave at a moment's notice. Hundreds of sandbaggers worked furiously to prevent a new tear in the weakening dike from worsening.
"The war is not yet won," said Brandenburg state's governor, Manfred Stolpe.
The north-flowing Oder, which forms a natural border between Poland and Germany, started flooding about three weeks ago after heavy rains in Poland and the Czech Republic.
Breaks in the 100-mile-long dike, 50 miles east of Berlin, turned a low-lying village region into a small lake last week.
Early Sunday, that water broke through the dike again and started flowing back into the river, raising the water level in Frankfurt an der Oder to a record high of about 21 feet.
That was only 1.5 inches from the top of the dike. Workers were filling new sandbags to make it taller.
In Poland, however, officials feared their dike would not hold and ordered residents to leave. Some people had just returned to their homes after being ordered to evacuate last weekend because of the first wave of flooding.
Those determined to stay in their homes had to sign a government statement saying they were doing so at their own risk.
"The situation is tragic," rescue worker Lidia Markindorf told Radio Zet. "We want to evacuate everybody because the stability of the dikes is very uncertain."
Elsewhere in Poland, the situation was improving.
About half of the 3,000 people evacuated two weeks ago from the historic city of Wroclaw were returning to their homes and beginning the nasty task of cleaning up.