The marker at Kaub, west of Frankfurt, is forecast to drop to the critical depth of 40cm early on August 12, according to the German Federal Waterways and Shipping Administration. At that level, most barges that haul goods from diesel to coal are in effect unable to transit the river. It’s set to continue dropping, to 37cm the following day.

Europe is facing its worst energy crisis in decades as Russia curbs natural gas flows, with regional tension high over its invasion of Ukraine. That’s sent prices soaring and pushed companies to use more oil and coal instead. The energy crunch has spilled over into the broader economy, sending factory costs surging and threatening to push some of the continent’s largest economies into recession.

While some barges will still be able to navigate the Rhine at Kaub, the dwindling water level illustrates how a climate crisis is compounding the region’s energy woes. Benchmark German power prices jumped to a new record on Wednesday. European natural gas and coal futures also surged.

Used by vessels to haul vital commodities, the Rhine snakes about 1,300km from its source high in the Swiss Alps through some of Europe’s most important industrial zones before emptying into the North Sea near Rotterdam. Companies including chemicals giant BASF and steelmaker Thyssenkrupp rely on the river to supply major industrial plants with fuels and raw materials.

“If levels at Kaub drop to 35cm-55cm in the next two weeks, some barges won’t be able to cross the Rhine at all, while others would carry less cargo,” BASF said Wednesday.

A mix of glacial run-off and rain feeds the river, but contributions from glaciers have dwindled in recent years as summer melting outpaces winter ice formation due to climate change. Below-average snowfall last winter and continued glacial attrition mean the waterway is particularly likely to fall to crisis levels, according to Switzerland’s federal weather service.

When the marker at Kaub hits 40cm or less, it becomes uneconomical for most barges to sail any further, according to Germany’s Federal Institute of Hydrology. That in effect halts the flow of most shipments beyond the waypoint.

Barges are still passing the river at Kaub, an official from the WSA, the German state waterways agency, said Wednesday by phone. He expects the vessels to continue to operate until the Kaub marker drops by about 20cm from current levels.

Further downriver at Duisburg, near Cologne, the level is at 172cm, with 150cm seen as the threshold that makes it uneconomical to transport materials like coking coal and iron ore by barge.

The measured water level isn’t the actual depth of the river, but rather a marker for navigability. Shipments have already been hampered for weeks, with low water limiting how much barges can carry. The rate to haul some fuel to Basel in Switzerland is now 267 euros (R4,455) a ton, compared with about 25 euros a ton in early June, data from Insights Global show.

The low levels could cause planning headaches for utilities like EnBW and Uniper, the latter of which recently received a $17-billion bailout from the German government to prevent a collapse of its energy network.

Grosskraftwerk Mannheim, which operates one of the country’s biggest coal-fired power plants, said that while shipments are currently restricted, enough coal is stockpiled at the facility to continue power generation for several weeks.

Companies will still be able to supply factories and power plants by road or rail, but those modes of transport are significantly more expensive, leading to a squeeze on margins.

“Railway capacities are not sufficient to compensate for missing barges,” said Juergen Osterhage, managing director for the German Coal Importers’ Association.