The barge clearance level at Kaub, a choke point for vessels heading to southern Germany and Switzerland, dropped as low as 21 centimeters (8.3 inches) overnight, the lowest since records began in 1880. It edged up slightly Tuesday morning, but is unlikely to offer lasting relief, as the Rhine typically bottoms out later in the summer. Forecasts already point to a drop to 17 centimeters by Saturday.
