While shippers await a possible easing of congestion at the Panama Canal in the coming weeks, the volume of U.S. LNG heading through the key route has fallen to a record low.

Under normal conditions, the canal provides the fastest roundtrip voyage from the Gulf Coast to Japan at roughly 49 days. However, persistent drought conditions in the region since last summer have pushed the Panama Canal Authority (PCA) to restrict passages, spiking wait times and auction prices for passage slots.

“Faced with low water levels at the Canal’s reservoirs, which are essential to its operations, we were forced to start restricting transits for the first time ever,” PCA’s Ilya Espino de Marotta, deputy administrator said in a recent operations summary. “This decision was crucial to...