By Nithin Sridhar
A recent study conducted by the Bangalore University (BU) on the management of odor that is being emanating from the waste water in the Vrushabhavathi valley has concluded that the cause for the foul smell in the surrounding areas is hydrogen sulphide present in the water due to the dumping of domestic and industrial waste into the river. These wastes have made the river water highly poisonous. But, this was not the case always.
The past grandeur of Vrushabhavati
River Cauvery is one of the most important rivers that flow through Karnataka. She has many tributaries like Kabini, Kapila, Hemavati, Arkavati etc. River Vrushabhavati, which flows through the south of Bengaluru, is one of the tributaries that feed Arkavati, which in turn feeds Cauvery.
The river is said to have sprung from somewhere near Dodda Ganapathi Temple on Bull Temple Road in Basavanagudi and flows parallel to present day Mysore road touching various localities in Bengaluru like Guddadahalli, Bapujinagar and RR Nagar.
It was a fresh-water stream that flowed in grandeur and fulfilled the drinking and other water needs of the people at one point of time. The river was not only fulfilling the daily needs of the people, but it was also considered as very sacred. As a result, in 1425, Sri Vyasaraya of Channapattana, who was also the Rajguru of Vijayanagara Empire, established a temple dedicated to Lord Hanuman called “Gali Anjaneya Temple” at the confluence of Vrushabhavati with Suvarnamukhi in south-west of Bangalore, which is still present.
Fresh-water river becomes a waste-water river
But, today the fresh-water river has completely dried and it has been replaced by a river of waste water that carries industrial effluents from more than 100 industries and sewage of Bengaluru with up to 300 million liters per day (MLD) of waste water flowing into the Vrushabhavati valley. These industrial effluents and domestic sewage that were diverted to the river especially in last few decades has killed the original fresh-water river and replaced it with a river of waste water.
The current condition of Vrushabhavati
A 2008 study found that around 57% of the total 30 samples collected from Vrushabhavati were non-potable. The major factors contributing to the non-potability of the water were hardness and excess of nitrates. Hardness contributed to the non-potability of water in 40% of the samples, whereas nitrates were present in excess in 43.33% of samples.
The report says that the excess of nitrates must have been caused due to water flowing through soil containing industrial and domestic wastes, as well as due to septic tanks and garbage disposals. Though the average concentration of nitrates was 47.6 mg/l, which is just below the Bureau of Indian Standards (BIS) permissible level of 50 mg/l, in some samples, the nitrate concentration was as high as 157 mg/l. Excess nitrates cause blue baby disease in infants.
The maximum values for hardness were as high as 1960 mg/l against BIS standard of 600 mg/land the major contributor for hardness were again the sewage and industrial effluent. The other causes of non-potability of Vrushabhavati water are the presence of calcium, fluoride, chloride, iron, dissolved solids etc.
Calcium was beyond permissible limits in around 23% of the samples whereas very high levels of fluoride were found in around 13% of samples. Four out of thirty samples had iron content higher than the permissible level of 1 mg/l. Excess chloride contributes towards 10% of non-potability, with the maximum chloride level being 1338 mg/l as against the permissible BIS limit of 1000 mg/l. The study further analyzed ten samples for bacteria and found that five samples, i.e. fifty percent were contaminated.
A 2013 report says that the levels for BOD and COD were much above the Indian Standards (IS) permissible levels. BOD or Biological Oxygen Demand refers to the amount of dissolved oxygen required for aerobic microbes to break down organic materials in water and is used to access the quality of water. The BOD levels in Vrushabhavati was around 253 mg/l at upstream and 248 mg/l at downstream as against IS level of 30 mg/l. COD or Chemical Oxygen Demand is also another parameter for assessing the quality of water. It was 340 mg/l and 320 mg/l at upstream and downstream respectively as against the IS level of 250 mg/l. These clearly imply that water is completely contaminated.
Another 2013 study concludes: “The analysis of Vrushabhavati river water samples reveals that the water is highly contaminated at selected points which are not suitable for drinking and irrigation. Pb, Cr, Mn, and Fe concentration is above the permissible limit. Even though the other metal concentration is below permissible limit, it is necessary to prevent excessive build-up of these pollutants which are transferred to soil and finally food.”
In 2013, following Karnataka High Court’s notice to the State government, Bangalore Water Supply and Sewerage Board (BWSSB) and other authorities, the Ramanagaram district administration had decided to take up the cleaning of Vrushabhavati river stream. But, much has not been done as shown by the recent study by Bangalore University.
There is only a single Sewage Treatment Plant (STP) that is treating the waters in the Vrushabhavati. Apart from this, Bengaluru has 13 more STP’s across the city. According to a 2007 report of Central Pollution Control Board, most of these 14 STP’s operate at only their 50% design capacity. As a result, much of the sewage is let into the rivers and streams without treating them.
It is high time that the government not only makes the present STP’s to run at their full capacity and build newer STP’s to cater to growing demands, but also makes efforts to revive the dead Vrushabhavati fresh-water stream, which would then help to fight water scarcity in Bengaluru.