Massive fish die-off witnessed in Sabarmati

AHMEDABAD: Hundreds of fishes in the Sabarmati have died due to pollution and water stagnation in the river. With no release of fresh Narmada water, severe algae bloom has occurred depleting dissolved oxygen in the river.

At the same time, summer temperatures have affected the water which is heating faster locally due to stagnation and lack of current causing fishes to die.

Experts say reduced level of oxygen in the river and pollution are the key reasons for the death of fishes in the Sabarmati.

The algae bloom, however, has been marked as the main cause causing lowering of dissolved oxygen levels in the water. Along with this, temperatures above 40 degrees celsius seriously affect water quality in stagnant water which is not reasonably deep — causing death of fishes said experts.

A senior AMC official said that the fish deaths and algae bloom is due to dumping of waste and untreated sewage in the Sabarmati. He said the summer could not be blamed, as then fish deaths would have occurred in all water bodies, like the Kankaria lake.

The officer pointed out that on an average the river receives 15% of the 960 million litres of untreated sewage which the city generates every day.

The city has the capacity to treat 817 MLD of sewage. A report by the Gujarat Pollution Control Board (GPCB) states that the Sabarmati had biological oxygen demand (BOD) of 8.6 and the chemical oxygen demand (COD) of 29 at the entry point of the city but the levels rise to 80 and 224 respectively at Vasna-Narol Bridge.

The permissible limit of BOD is 30.