Ganga’s water did not improve during lockdown; less flow may have deteriorated quality
The quality of the water in the Ganga did not improve and rather deteriorated at many stretches including possibly due to the discharge of untreated or partially treated sewage despite curbs on human activities during the 68-day lockdown imposed from March 25 to check the Covid-19 pandemic, according to a Central Pollution Control Board (CPCB) report released on Wednesday. Seven out of 19 major rivers in India, including the Brahmani, however, recorded an improvement in water quality in April, as compared to the period before the lockdown, it added.
The Ganga’s compliance with primary water quality reduced from 64.6 % to 46.2% during the lockdown. The report suggests that this may also have been because of negligible seasonal flow, which increases the concentration of pollution, and no freshwater discharges from the upstream. Compliance also reduced in the Beas, the Chambal, the Sutlej, and the Swarnarekha.
The Baitarani, the Mahanadi, the Narmada, and the Pennar were 100% compliant with outdoor bathing water quality criteria.
The CPCB sought to assess percentage variation (increasing or decreasing) trends in water quality only for bathing criteria parameters such as pH, DO (dissolved oxygen), BOD (biological oxygen demand), and FC (Fecal Coliform excluding Fecal Streptococci). These are all measures that show if a river can sustain life and is safe for bathing.
For the Ganga, during pre-lockdown, 42 out of 65 monitored locations (64.6 %) and during the lockdown, 25 out of 54 monitored locations (46.3 %), were found to be within the desirable limits of primary water quality criteria for outdoor bathing.
The Brahmani river’s compliance with primary water quality criteria for outdoor bathing improved from 85% in the pre-lockdown period to 100%. For the Brahmaputra, it improved from 87.5 % to 100 % and for the Cauvery from 90.5 % to 96.97 %. In the case of the Godavari, it went up from 65.8% to 78.4 %, the Krishna 84.6 % to 94.4 %, the Tapi 77.8 % to 87.5 %, and the Yamuna 42.8 % to 66.67 %.
Manoj Mishra, convenor of the Yamuna Jiye Abhiyan, said the lockdown happened during the lean season for all rivers, particularly those originating from the Himalayan region. “The river flow contributes to the dilution of pollutants. So, their analysis pertaining to the Ganga and other Himalayan rivers is correct.”
Mishra said rivers including the Narmada, the Pennar, and the Mahanadi anyway have a low industrial effluent load. “So, it is not a surprise that they met bathing water quality standards before and during the lockdown.”
Mishra said CPCB should not have compared apples with oranges because the issues facing these rivers are very different. “The clear impact of lockdown was seen in the Yamuna downstream of Wazirabad because it has high industrial effluent load which became nil during the lockdown and in March and April… there was rain in Yamuna’s catchment leading to higher water discharges.”
The 2,525-kilometre-long Ganga originates in the northernmost part of Uttarakhand, flows through Uttar Pradesh, Bihar, Jharkhand, and West Bengal before it discharges into the Bay of Bengal.
The report said the lockdown period offered a unique situation to carry out assessment of water quality of surface water bodies including major rivers. It provided an opportunity to re-comprehend and redesign existing frameworks and put in place robust mechanisms to cleanse identified polluted river stretches, it added.
CPCB scientists said there might be separate reasons behind the improvement of water quality in Yamuna during the lockdown and the worsening of the condition around the same period in many stretches of the Ganga.
“We found that the water in the Ganga had improved in Uttarakhand and some stretches of UP during the lockdown. However, no improvement was seen in West Bengal and Bihar in the downstream. This combined with a lean flow led to fewer locations recording improvement in the quality of the river water. Sewage may have a higher contribution to pollution in these stretches. While in Yamuna the contribution from industrial effluents, which was nil during the lockdown, appears to be moderate. Yamuna in Delhi received freshwater from upper reaches during the lockdown. There were rains in the river’s catchment areas in upper reaches in March, according to our analysis,” said a CPCB scientist, who was involved with the study, on condition of anonymity.
CPCB separately observed its 46th Foundation Day on Wednesday and announced its plans for the next decade until 2030 to provide technical leadership for “science-based environmental management” and guiding policy decisions to the government.