Lockdown: Ganga flows cleaner though just marginally2 min read . Updated: 29 Apr 2020, 04:46 PM IST
- Sewage totalling about 3,500 million litres per day (MLD) is discharged into Ganga
- Experts have said the analysis downplays the impact of industrial effluents - significant source of pollution in Ganga
NEW DELHI: A significant drop in industrial wastewater discharges and agricultural run-offs amid the lockdown, in place since 25 March, has breathed fresh life into the otherwise polluted Ganga, the Central Pollution Control Board (CPCB) has said in its post-lockdown analysis of the river water quality.
The improved water quality comes on the back of a marginal increase in dissolved oxygen (DO) levels and reduced nitrate concentration in the river, according to the analysis carried out by CPCB after collecting data from the 36 real-time water quality monitoring stations in the river before and after the lockdown.
DO is a crucial indicator of water quality and thus provides a gauge of how well the water can support aquatic plant and animal life. A higher value indicates better water quality. According to the data, DO concentrations remained above the bathing criteria norms (5mg/l) at all locations, except in parts of Uttar Pradesh, where it has gone down.
“This may primarily be attributed to absence of industrial wastewater discharge, agricultural runoff and increased fresh water flow in the river. (A decline in) general human activities at ghats and entrainment of solid organic waste into the river may have also contributed," said CPCB.
It, however, clarified that the improvement was “not substantial" as there was no significant reduction in other indicators- biochemical oxygen demand (BOD) and chemical oxygen demand (COD) and concentrations of ammoniacal nitrogen, which is seen to have gone up in certain locations.
According to the analysis, this could be due to the unabated discharge of domestic wastewater from over 97 towns situated along the river in different states.
Sewage totalling about 3,500 million litres per day (MLD) is discharged into Ganga, of which only 1,100 MLD is treated discharge. About 300 MLD of it is industrial effluent comprising about 9% of total wastewater discharged into the river daily.
Experts, however, argue that the analysis downplays the impact of industrial effluents, which are significant sources of pollution in Ganga.
“Even if the industrial effluents contribute only 9% to the wastewater discharge, their impact is ten times more than sewage water. So, if there is no release of industrial effluents into the river, then water quality should have improved much more than what has been shown in this analysis," said Professor Vinod Tare, from Indian Institute of Technology (IIT), Kanpur, who also heads the Centre for Ganga River Basin Management and Studies.
Days into the lockdown, people living in the towns situated near the river have shared videos of how rivers have been flowing cleaner, with more aquatic life visible near the banks.
“There is so much visible evidence to show how our rivers have cleaned up. In some places, the water has become drinkable. CPCB should be closely monitoring this data every week for the entire period of lockdown, especially the role of industrial effluents which is key for the pollution control mechanism," said Himanshu Thakkar, environmentalist and water expert.
The CPCB has also analyzed water quality of Ganga's tributaries including Banganga, Rāmgangā, Kali, Pandu, Varuna and Gomati located in Uttar Pradesh and Falguni and Maya located in West Bengal, finding marginal fall in BOD, COD and nitrate levels and similar water quality as Ganga.