KUALA LUMPUR, April 21 — Around a million people in Johor may be affected by water disruptions as three dams in the state supplying raw water to treatment plants have fallen below their critical marks.

The Sunday Star reported the National Water Services Commission (SPAN) as saying the Lebam, Upper Layang, and Pulai 2 dams are now at 15.9, 21.8, and 36.1 per cent, respectively.

The decline is due to the prolonged heatwave in some parts of the country despite occasional thunderstorms elsewhere.

Lebam dam provides water to treatment plants that supply around 100,000 people living in Bandar Penawar, Kota Tinggi, Pengarang, Tanjung Balau, and Teluk Ramunia.

The Upper Layang dam supplies water to the Sultan Iskandar treatment plant that serves 600,000 residents in Pasir Gudang and the eastern part of Johor Baru, including Bandar Seri Alam, Johor Jaya, and Permas Jaya.

SPAN also indicated the weather has resulted in drops to Sungai Sedili Kecil’s water level, resulting in a fall in treated water output at the Lok Heng plant in Kota Tinggi that disrupted 4,004 households and premises until last Sunday.

It urged all state governments and water operators to closely monitor the situation in dams and rivers supplying water to treatment plants so that early measures can be taken to deal with any possibility of water supply disruption.

Separately, SPAN said the water level situation remains normal in Selangor, with storage dams all above 79.2 per cent.

The same goes for Melaka, Negri Sembilan, Perak, and Penang, with the Air Itam dam rising from 49.9 last month to 52.8 per cent, as of last Thursday.