RimbaWatch said satellite imagery showed that the reservoir is being muddied through deposits from the Ulu Muda river, which flows through logging operations upstream.

“Satellite imagery shows that logging operations re-commenced in Ulu Muda beginning in 2021, with activities accelerating in 2022 and 2023.

“It further shows that the lake began to be potentially tainted through mud and other sediments deposited from the Ulu Muda river in early 2023,” RimbaWatch said in a statement.

The NGO said satellite imagery also showed that in October and December 2023, the river was visibly muddied and was depositing this mud into the Tasik Muda reservoir.

“The Tasik Muda reservoir supplies water to Kedah and regulates water flow into the lower Muda river, where the Sungai Dua intake supplies up to 80% of Penang’s water,” it said.

It said impediments at the reservoir had affected Penang’s water supply in the past.

“While Penang has called for a halt to logging in the Ulu Muda area, Kedah has argued that it would lose state revenue if it stopped logging and has continued to allow timber activities in the state,” it said.

This is despite the fact that the Kedah government had in 2018 cancelled logging permits in Ulu Muda.

RimbaWatch said the state government must also put a stop to logging activities within the Ulu Muda forest reserve and investigate the impact of such activities on the reservoir’s environment.

It also urged Sirim to revoke timber certification for the Kedah forest management unit (FMU), under which the Ulu Muda forest reserve falls.

It urged the international forest certification body, Programme for the Endorsement of Forest Certification (PEFC), to investigate Sirim’s certification for FMUs and to declare a moratorium on endorsing the Malaysian Timber Certification Scheme (MTCS).

RimbaWatch said nations such as Japan, the Netherlands and the UK, as top consumers of Malaysian timber products, should halt imports until all issues identified can be rectified.