The level of the Rhine near Basel has fallen so low because of the current drought that shipping is being hampered.
On Saturday it was only 4.95 metres deep, the shallowest it has been since the hot summer of 2003.
Barges are able to load only between a quarter and a third of their normal cargo, otherwise they would be too low in the water, Peter Sauter of the Swiss Rhine Ports told the Swiss news agency.
Heinz Amacker, head of the container shipping company Danser Switzerland told the Basler Zeitung that he was having to spread loads, which means chartering more vessels. "In the long term that is not economic for us," he warned.
Basel is home to four ports, where goods shipped to and from centres down river as far as Rotterdam are loaded onto land transport. Low water levels are affecting the Rhine in Germany as well.
Passenger shipping upstream is also facing difficulties. Traffic has been halted on the 10 kilometre stretch between Stein am Rhein and Diessenhofen, and ships replaced by buses.
No immediate improvement of the situation is in sight: the dry weather is forecast to continue.
swissinfo.ch and agencies