BERLIN (AP) — Germany's main industry lobby group warned Tuesday that factories may have to throttle production or halt it completely because plunging water levels on the Rhine River are making it harder to transport cargo.

Water levels on the Rhine at Emmerich, near the Dutch border, dropped by a further four centimeters (1.6 inches) in 24 hours, hitting zero on the depth gauge.

Authorities say the shipping lane itself still has a depth of almost 200 centimeters (six feet, six inches), but the record low measurement Tuesday morning highlights the extreme lack of water caused by months of drought affecting much of Europe.

“The ongoing drought and the low water levels threaten the supply security of industry,” said Holger Loesch, deputy head of the business lobby group BDI.

Loesch said shifting cargo from river to train or transport was difficult because of limited rail capacity and a lack of drivers.

“It's only a question of time before facilities in the chemical and steel industry have to be switched off, petroleum and construction materials won't reach their destination, and high-capacity and heavy-goods transports can't be carried out anymore,” he said, adding that this could lead to supply bottlenecks and short-time work might result.

Loesch warned that energy supplies could also be further strained as ships carrying coal and gasoline along the Rhine are affected.

He echoed concerns that climate change could make droughts more frequent in the future, and urged the government to help closely monitor water levels and react early to potential transportation problems on Germany's waterways.

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