Ecologists attribute the phenomenon to the rise in pollution. “A small number of fish have died apparently due to pollution. The possibility of the fish dying of a disease is remote for the number in that case would have been larger,” an official said.

Ishwar Singh, deputy conservator of forests and other officials visited the far-end of the water body this evening. It appeared that the organic matter at the bottom of the lake was decaying, resulting in a stench, sources said.

Ecologists feel the time is running out for the administration to save the lake from an ecological calamity. Trash dumped at the lake is spelling doom for the aquatic fauna in the water body, promoted as a tourist destination.

The waste material degrades the quality of water thereby harming the ecological balance and making the survival of aquatic flora and fauna difficult, ecologists say.