As sewage continues to filter in through urban centres, the number of polluted river stretches in the State has gone up in the past three years. A total of 17 stretches of rivers in Karnataka have been classified as polluted in the Central Pollution Control Board (CPCB’s) River Stretches for Restoration of Water Quality report published in September. In the 2015 report, there were 15 such stretches in the State.
However, what is also telling is that many stretches have been bumped up a notch in the priority for restoration. In the 2015 report, all the major rivers were classified in Priority IV or V, that is, the biological oxygen demand (BOD) measures were consistently between 6 and 10 milligrammes per litre (for Priority IV) or between 3 and 6 mg/l (for Priority V).
However, in the 2018 report, Arkavathi, Lakshmanthirtha, Malaprabha, and Tungabhadra have been classified as Priority III stretch for restoration as the BOD levels have exceeded 10 mg/l. Arkavathi remains the most polluted river with 14 mg/l as measured near Kanakapura town. Three years ago, Arkavathi registered an average BOD of less than 8 mg/l.
In the recent report, Assangi nala (Belagavi), Kumaradhara and Netravathi rivers (both in Dakshina Kannada district) have made it to the list, perhaps as a reflection of the increased water quality stations being used. The CPCB monitored data in over 445 rivers, including in 61 locations in Karnataka. Much of the pollution stems from the 24 urban centres that have sprawled along the rivers.
Worsening situation
A look at the Karnataka State Pollution Control Board’s (KSPCB’s) monitoring data between 2015-16 and 2017-2018 shows a stagnation in the water quality of major rivers, even though much has been spent on sewage treatment plants in major urban centres. Of the 82 rivers being monitored, just seven could be used for outdoor bathing, while 12 could no more be drinking water sources. The majority — 63 — needed advanced disinfection if they were to be used for drinking purposes.
“Most towns and cities here have no method of disposing sewage. In some towns, Sewage Treatment Plants (STPs) are being constructed, but it may take at least four years to see any sort of result,” said Lakshman, KSPCB Chairman. This has seen rivers such as the Malaprabha, Tungabhadra and Arkavathi — which receives much of the industrial effluents from Peenya and Bengaluru — deteriorate in quality. He claimed the regulatory body had already brought many temples along the rivers to manage the sewage generated, while notices have been sent to sugar industries that are major polluters, to treat their effluents.
Surprisingly, Lakshmanthirtha, a tributary of the Cauvery, which has very few major urban centres around it, has deteriorated in the KSPCB’s monitoring: from ‘C’ grading, signifying drinking water after disinfection in 2015 to ‘E’ grade, the lowest possible quality in a water body.
However, Mr. Lakshman blames this on their monitoring station.
“It is currently placed next to a drain in Hunsur. During summers, it only registers sewage quality water for the whole river, which is misleading. The KSPCB will be shifting this and other monitoring stations to get a better picture of the rivers,” he said.
