KUALA LUMPUR, Nov 10 — Early investigations by the Selangor Water Management Authority (Luas) indicated the odour pollution of Sungai Selangor could have come from an unsanctioned effluent discharge at an Indah Water Konsortium facility in Rawang.

It identified the plant as IWK GBK 225 waste treatment plant in Taman Velox, Rawang, which it said had released the effluents without authorisation through a nearby manhole.

"The distance of IWK plant to the Rantau Panjang water treatment plant is estimated to be 12km,” Luas said in a statement.

The Rantau Panjang plant was forced to shut down operations at 12.20pm, followed by the SSP1, SSP2, and SSP3 plants by 1pm.

This was after odour pollution was detected in the Selangor river. Up to eight tonnes of odour pollution was detected face-down (muka sauk) at the Rantau Panjang plant, and four tonnes at the SSP1, SSP2 dan SSP3 plants.

"Luas has activated its Code Red per its water source pollution emergency manual, as well as taking steps to decontaminate this by placing 37 bags of activated carbon to control the pollution at the location.

"We have also activated the Bestari Jaya pool pumping operation (Operasi Pengepaman Air Kolam) of up to 192 million litres a day, to increase the dilution factor,” it said.

The river gates in Baraj Bestari Jaya have also been raised to flush out the water and increase the flow to the river stream.

"This unscheduled water disruption is expected to affect 1,139,008 accounts encompassing 1,279 areas in Kuala Lumpur, Petaling, Klang, Shah Alam, Kuala Selangor, Hulu Selangor, Gombak, and Kuala Langat.

"Luas, Air Selangor and other parties are working around the clock to conduct investigations and take mitigation steps to overcome this incident,” Luas said.