The Kedah Department of Environment (DOE) is investigating the cause of the pollution upstream of Sungai Kulim, believed due to pig farming activities in Sungai Lembu, Seberang Perai Tengah, Penang.

Its director, Sharifah Zakiah Syed Sahab, said the investigation was conducted following a Notification of Pollution Event (NPE) Level 1 at Sungai Kulim received by the department at 11am last Friday.