Mumbai’s Mithi among the three most polluted rivers in Maharashtra

Data from study of 29 rivers by pollution control boards between 2012 and 2015 revealed the poor condition of these rivers

Mithi in Mumbai, Mula in Pune and Kundalika in Raigad district are the three most polluted rivers in the state. This information was revealed through a reply by the Central Pollution Control Board (CPCB) to an application under the Right To Information (RTI) Act filed by city-based non-governmental organisation NGO Vanashakti.

Along with Mithi, Mula and Kundalika rivers in Maharashtra have been identified as most polluted. (HT File)

The rivers were classified as the state’s dirtiest after measuring biological oxygen demand (BOD) in the water. BOD indicates the concentration of oxygen required to sustain aquatic life. High levels of BOD indicate concentration of untreated sewage. Unpolluted rivers have a BOD below 1 mg/litre, while the level is between 2 and 8 mg/L in moderately polluted rivers. Untreated sewage averages between 200 and 600 mg/L while treated sewage has levels of 20 mg/L or less. The study said Mithi, Mula and Kundalika have an average BOD level of 50mg/l, almost nine times the accepted national standard. The source of sewage for all three river stretches were identified as untreated domestic sewage and industrial effluents.

The data, which has not been reported so far, comes from a joint study of 29 rivers by the CPCB and the Maharashtra Pollution Control Board (MPCB) between 2012 and 2015.

“This was a pan-India study under our National Water Quality Monitoring Programme where pollution levels were checked at 150 major river stretches,” said a senior official from CPCB.

The official said the analysis divided the rivers into five main priority lists — from high pollution (priority 1) to the lowest (priority 5). “State pollution control boards were directed to take immediate action to improve water quality at priority 1 rivers and overtime ensure all rivers were cleaned up,” he said. ”Water bodies with BOD of more than 6 mg/L are considered polluted and identified for remedial action.”