Low water levels on Indonesia's Mahakam River have disrupted coal barge shipments in East Kalimantan, forcing operators to reduce cargo loads and raising the risk of inventory build-ups at mines and loading ports, Bloomberg Technoz reported on September 8, citing the Indonesian Coal Mining Association (APBI).

The decline in river levels, linked to dry conditions associated with the El Nino weather pattern, has restricted the draft capacity of coal barges operating along one of Indonesia's key coal transportation routes.

"Current conditions could affect the smooth delivery of coal supplies and potentially increase temporary stocks at mining sites and loading port stockpiles," APBI Executive Director Gita Mahyarani said.

The association said it was not yet able to estimate the volume of coal exports affected by the disruption, but warned that logistics constraints could continue if dry conditions persist.

The Mahakam River, which runs through Indonesia's coal-producing hub of East Kalimantan, is a critical transportation corridor used by barges carrying coal from mines to export terminals.

The Samarinda Port Authority (KSOP) has instructed companies and port operators to limit coal loads on barges to around 5,500-6,000 tonnes, compared with a normal capacity of about 7,000 tonnes, to reduce the risk of vessels running aground in shallow waters.

"Under normal conditions, one barge can carry around 7,000 tonnes, but the load must now be reduced because the draft affects navigation safety," KSOP Samarinda head Mursidi said.

Some barges were still facing difficulties navigating the river even after reducing their cargo loads. The lower carrying capacity has increased the number of trips required and pushed up coal transportation costs.

Indonesia is one of the world's largest coal exporters, with China and India among the main destinations for coal shipments from East Kalimantan.

The disruption comes as other major coal routes in Kalimantan, including the Barito River, also face water-level declines. Industry groups have warned that prolonged dry conditions could delay millions of tonnes of coal shipments and pressure export flows.

Coal producers and traders are closely monitoring the situation, as extended transportation bottlenecks could affect supply availability, export schedules and logistics costs in Southeast Asia's largest coal-exporting nation.