Months of scarce rainfall and hot sunny weather drove water levels on the Rhine to a record low, forcing ship operators to suspend services to keep vessels from running aground.
"We haven’t had any new ships in Cologne since last week—they stop in Duisburg" 80 kilometres (50 miles) north, Oliver Grossmann, head of shipping company CTS, told AFP.
He said that under normal conditions, "three or four" of his big vessels would stop each day in the city known for its Gothic cathedral.
The few barges still chugging along the river have had to drastically reduce their cargo to stay afloat.
Sitting in his office overlooking the mountain of containers, Grossman said rail links can only fill part of the gap as long as river transport is paralysed because of a lack of infrastructure and train engineers.
‘Need intense, widespread rainfall’ At the entrance to the port of Duisburg, a small tower houses a Rhine measuring station.
On its roof are two LED panels reading 1.55 meters (5.09 feet).
"This is the lowest level ever measured here," said Jan Boehme, a hydrologist with the Water and Shipping Authority.
But since the dry spell began, industrial giant Thyssenkrupp has had to cut back production at its Duisburg plant "because a sufficient supply of raw material cannot be assured", a company spokesman said.
Abandoned and long-submerged bicycles have resurfaced by the hundreds.