Europe’s busiest commercial waterway is being closely watched after dryness last summer left it effectively unnavigable. As well as moving fuels like diesel and heating oil inland, the Rhine also handles coal, chemicals and metals. 

The barge clearance level at Kaub, a narrow point on the river that vessels can struggle to pass on their journey inland, are at their lowest for the time of year for at least 30 years. Water levels at that point are forecast to drop through July 1. 

Barges hauling fuel from the Rotterdam area beyond Kaub can currently carry just over 1,200 tons of fuel, according to Riverlake Barging. That has fallen from about 2,000 tons a week ago.

Last year’s dry weather, coupled with a spate of refinery outages in south Germany, left parts of inland Europe short of fuel. One of four oil-processing plants in south Germany has suffered disruption in diesel production this week, also tightening supply of fuels in the area. 

Barge rates for moving heating oil to the Upper Rhine are already high for the time of year. 

Bayernoil, which operates an oil-processing complex, took a big diesel-making machine known as a hydrocracker out of service this week, according to Wood Mackenzie. The complex has suffered disruption to wholesale diesel supplies this month.