The rivers downstream of coal mining areas and cement plants have acquired the colour blue since five years back, a phenomenon baffling even environmental scientists of the state.
The Delhi-based Central Laboratory of the Central Pollution Control Board, which conducted an analysis of water samples collected from these rivers, said that the water was highly `acidic` rendering it unsuitable to support life forms.
The latest report, submitted by the Meghalaya State Pollution Control Board to the state government and the Central Pollution Control Board, Delhi, said, "Mine run off from coal mines are the major probable causes of water pollution in the area."
"The undesirable change in water quality affects a variety of flora and fauna of the rivers. Fish, as such, are susceptible to acidity and low pH values are unsuitable for most aquatic organism," the report said.
Five years back, river Lukha in the Khliehriat sub-division turned blue and all aquatic life, including fish, died and were found floating in the river. .
The board said, "Acidification of natural water is mainly due to acid effluents discharged from coal mines."
The state pollution control board had in 2007 also conducted a thorough investigation into the sudden blue pigmentation of the Lukha river.
The report of the investigation said, "The blue colour of the Lukha is possible because the river receives untreated waste discharge from coal mine areas of Sutnga, Ladrymbai and Sakhain, compounded by heavy rain."
Incidentally, water samples collected downstream of a cement plant (Umtyrngai river) is alkaline in nature and did not `contribute` to the acidity of the Lukha river, a confluence of Lunar river and Umtyrngai.
The MSPCB said, "The prevailing condition of water quality in the area requires urgent need for initiating preventive and control measures to minimize impact of mining activities on water quality."
It also suggested filling up of abandoned mines to prevent generation of acid mine drainage or initiate proper management of it by treating it actively or passively.