by Syed Akbar, originally posted on February 04, 2017

HYDERABAD: The quality of water in the Nagarjunasagar (NS) reservoir, the main source of drinking water for Hyderabad and thousands of villages in Andhra Pradesh and Telangana, is gradually deteriorating with researchers recording an increase in organic and mineral contaminants in five years. Over a crore people are dependent on the reservoir for drinking water and irrigation. Doctors warn of an irreparable health impact in the long run.

Mineral and organic contaminants in the reservoir’s water is a result of unchecked use of pesticides and fertilisers by farmers on thousands of acres in its catchment area. Agricultural waste -particularly nitrogen-phosphorus-potassium (NPK) fertilizers -is harmful.Researchers say there has been a 10-15% increase in pollutants in the reservoir since 2010.

Satellite images of the reservoir across the Krishna show how the level of contaminants changes depending on water inflows from upstream. While rainwater runoff during monsoon brings in large quantities of contaminants, this is diluted as water levels remain high during this period. The lowest contamination level can be seen in November and December. Pollution levels start rising from January and peak during AprilMay . In January , contamination starts at inlets and by May spreads to almost 90% of the reservoir when the total area of water spread is also reduced by half without rains.

Though contaminants do not pose an immediate danger, they accumulate in tissues of aquatic beings. Those consuming fish from such reservoirs, for instance, will have severe health issues in the long run, warn researchers. Food grown using such water gets contaminated as well.