Perlis DOE director Fitri Said said an investigation paper had been opened for further action.

He urged industries to always comply with measures prescribed under the Environmental Quality Act 1974 to safeguard the environment and rivers in the state.

“We have taken action to stop the operations of the factory near the area,” he said when asked to comment on the pollution in Sungai Ngulang.

He said action could be taken against anyone who breached the Environmental Quality Act 1974, which provides for a maximum fine of RM100,000 and up to five years’ jail upon conviction.

The Malaysian Nature Society (MNS) president Ahmad Ismail said pollution in the river was a recurring incident, reportedly due to effluents discharged from nearby industrial areas.

He said the DOE, the drainage and irrigation department, local authorities and the community should take action to ensure that the water quality index (WQI) of rivers remained in the first-class category.

“We are not against factories but they should comply with the criteria set by the authorities so that the discharge of effluents is better controlled to preserve rivers in the state,” he said.

Based on the DOE criteria, water from rivers with first-class WQI is safe for drinking, requires only minimum treatment and is suitable for aquatic life.

A food stall trader in Kampung Ngulang here, Norma Said, 60, said she hoped the problem of river pollution could be resolved immediately because the area was popular for fishing.

“When the river is polluted, the water turns black and is not clear as usual,” she said.