Shillong, Feb. 24: A new scientific report on the cause of fish deaths and water contamination from the Lunar-Lukha confluence to the Ummutha river in Jaintia Hills has revealed that the water at several locations is not fit for human consumption.

The report, prepared by the Meghalaya Pollution Control Board, has warned that “under no circumstances should the water be used for drinking in this stretch.” The samples collected from eight locations of the river reveal that the water is unfit for human consumption.

In November, several dead fishes were found floating on the Lukha river after it had turned blue. Since 2007 the water has turned blue at regular intervals.

The Meghalaya State Pollution Control Board carried out a detailed scientific study after the first incident was reported in February 2007.

The report had cited unscientific coal mining as the reason behind the death of fishes.

The pollution board scientists collected samples from eight different locations, including the Lunar river, Myndihati village, Khaddum village, Lukha river and the point of confluence of the Lunar and Lukha, after fish deaths were reported again last year.

Samples were also taken from 20 metres downstream from the point of discharge of effluents from Cement Manufacturing Company Limited, which is producing Star Cement, to the Umtyrngai river and also from Ummutha river (downstream of the Umtyrngai).

These were the same areas from where the samples were collected in 2007 when the death of fishes was reported for the first time in the state.

The water characteristics in terms of pH, sulphate and iron concentrations indicate that there is significant deterioration of the river in comparison to 2007.

The report said in these areas there is low pH and high concentration of sulphate and iron.

Acid mine drainage from abandoned mines and mine runoff from coal mines were the major causes for water pollution in the areas investigated, the report added.

“The undesirable change in water quality affects not only human beings and their activities but also flora and fauna of the area. Fishes are very susceptible to changes in water quality mainly acidity and low pH values are unsuitable for most aquatic organisms,” the report said.

According to the report, as far as blue colour of the river is concerned, the monitoring data is not sufficient to accurately indicate the specific parameters responsible for such colouring phenomenon.

After the samples were analysed initially by the Pollution Control Board scientists, the pesticide analysis of the samples were carried out by the Central Laboratory of Central Pollution Control Board, Delhi.

The analysis was carried out in accordance with the standard procedure of American Public Health Association, American Water Works Association and Water Environment Federation.

The pH value of most of the sampling locations ranged from 2.7 to 4.3, lower than the desirable limit of 6.5-8.5 prescribed by Bureau of Indian Standards (BIS) for drinking water.

The colour of the water at several stretches was yellowish brown and in some areas blue. However, the colour of the water in the Lukha river near Sonapur bridge was found to be blue.