At least two rivers in eastern Meghalaya have turned blue again apparently due to “high acid content”, resulting in death of scores of fishes.

The Lukha river in East Jaintia Hills district and certain sections of the Myntdu river in West Jaintia Hills district have changed their colour to a bright sky blue indicating a very high acid content. “We have observed that the Lukha has slowly changed its colour in the past few days after the monsoon rainfall subsided. The colouration has worsened and the whole river has turned into bright sky blue,” Sonapyrdi headman J S Lamare told PTI.

Although the colouration was first detected way back in 2007, no one has been able to find out the reason for the colouration, leaving scientists and environmentalists baffled. The Meghalaya State Pollution Control Board (MSPCB) in its 2012 report blamed acid effluents from coal mines as the major probable causes of water pollution in the area.

The Delhi-based Central Laboratory of Central Pollution Control Board had earlier ruled out the possibility of the water sustaining any life form due to its high acid content besides declaring it unfit for human consumption. Local environmentalist HH Mohrmen has demanded a thorough and independent test to find out the causes.