SÃO PAULO, BRAZIL — A severe drought in northern Brazil has significantly lowered water levels on the Tapajos waterway, bringing grain shipments to a standstill.

Brazilian port terminal group Amport, which represents firms such as Cargill and Louis Dreyfus, told Reuters that navigation of barge convoys carrying grains in the Tapajos has been halted since Oct. 4, and is expected to resume in November if rains arrive as forecasted.

Tapajos links Brazil’s central and north regions. It is an important corridor to transport grains from agricultural heartlands in states, including Mato Grosso, Brazil’s top soybean producer, to ports in the Amazon region. Amport said companies are waiting for the river to rise by at least 20 centimeters (7.9 inches) to safely resume navigation.

The drought also halted shipping of grains in September through the Madeira River, another important grains corridor for Brazil, the world’s largest producer and exporter of soybeans and second largest for corn.