Brown liquid in water: Ahmedabad's Raska plant remains shut

The Raska water supply plant remained shut for the fifth day on Saturday following the emergence of a dark brown liquid, but what is murkier is the failure of the authorities to diagnose the problem.

Officials now reveal that since Tuesday, there were three days when spurts of brown coloured Narmada-fed Mahi waters entered the Raska plant at least four times a day.

The AMC has been adamant about keeping the plant shut till it gets clear supply from the irrigation and water resources department.

Police, the AMC, and the Gujarat Pollution Control Board (GPCB) have been unable to agree on the cause of the dark discharge.

The AMC traces it to a chemical dump with high suspended solids (SS) detected near Jalampura village.

But the GPCB engineers say that the brown colour points to a particular species of algae present along the benthic (side lining) portion of the canal and also present in silt at Wanakbori dam.

But the AMC has strong reasons to debunk the theory. The suspended solids at Jalampura village towards Ahmedabad were detected at 1,414 miligrams (mg) per litre.

But at Wanakbori dam, the suspended solids were negligible, at just 14 mg per litre, while at Vasna village the value was 18 mg per litre.

As for chemical oxygen demand (COD) measured at Jalampura, the GPCB says the value of the dark brown liquid was 268 mg per litre, and it dropped to 25 mg per litre after the same liquid was filtered.