Dissolved oxygen content up from 8% to 56.5% in UP stretch of river Yamuna

The water quality in the stretch of river Yamuna that passes through Uttar Pradesh has improved considerably, thanks to the lockdown that has closed industries and

The water quality in the stretch of river Yamuna that passes through Uttar Pradesh has improved considerably, thanks to the lockdown that has closed industries and kept people away from the river.

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A report on water quality of river Yamuna, prepared by the Uttar Pradesh Pollution Control Board (UPPCB), said the dissolved oxygen (DO) level in the river has gone up in the range 8% to 56.5% during the lockdown period at six locations -- upstream, Vrindavan (39.6%), downstream, Vrindavan (38.46%), upstream, Mathura (48.3%), downstream, Mathura (56.5%), upstream, Kailashghat in Agra (12.5%) and downstream at Taj Mahal, Agra (8.0%) -- when compared to the pre-lockdown period.

According to UPPCB officials, the study took into account the pre-lockdown period (as on March 7, 2020) and lockdown period (as on April 8, 2020).

“To assess river health, we need to study f three parameters – DO, BOD and total coliform. It is required that BOD should be low and DO higher. If DO is low, then the aquatic life will not be able to survive. Likewise, contaminants in form of total coliform should also be low in order for improved water quality,” Utsav Sharma, regional manager, UPPCB, said.

A periodic report released in January 2020 by the UPPCB states that the DO level ranged between 1.5 milligrams/litre (mg/l) and 4.8mg/l at the 14 sampling points, starting at Okhla Barrage and ending at Firozabad in Uttar Pradesh.

In contrast, officials during the latest study found that on April 8 (during the lockdown period), the values of DO were considerably higher than on normal days and ranged between 5.4mg/l and 7.4mg/l at the six locations. On March 3 (pre-lockdown), the DO values ranged between 4.6mg/l and 5.6mg/l at these locations.

The biochemical oxygen demand (BOD) -- the amount of dissolved oxygen needed for organisms to break down organic material present in water -- also came down and was in the range of 17.6% to 23.1% during the lockdown period.

Another parameter of river water quality is the total coliform content. If the total coliform bacteria are found in a water sample, it indicates surface contamination has reached the water. The UPPCB study indicated that the total coliform content declined in the range 12.9% to 38.6% during the lockdown period, when compared to the pre-lockdown period.

“The decrease in total coliform in April 2020, as compared to that in March 2020 at all (six) locations indicates that the improvement in the water quality is principally due to dilution as a result of increase in water flow,” the report said.

According to UPPCB, the average discharge of water in river Yamuna from the Gokul Barrage during the pre-lockdown period (March 5 to March 7, 2020) was about 3,120.70 cusecs. But it was 7,938.3 cusecs during the lockdown period (April 6 to April 8, 2020), an increase of about 154.4%.

Experts said the data gathered during the lockdown period will provide a useful baseline for further studies.

“The lockdown was unprecedented. The data will give us a useful insight on the effect of pollution on the river’s health. Until now, our focus was more on treatment of sewage/drains etc. But during the lockdown, the drains/sewage are still discharging into the river, but industrial discharge is minimal. Now we will know how much industrial/commercial activities impact the river. Since the industrial activity is significantly reduced, in the future, we need to focus on the removal of all such sources of pollution,” Manoj Misra, convener, Yamuna Jiye Abhiyan, said.

“Near Okhla, there is reduced DO level but it increases near cities such as Vrindavan and Mathura. That is because for this 150km stretch of the river, there are no major cities along it. So the river gets a period of relief. The lockdown period study will also help us know the level of flow needed to maintain the health of Yamuna,” Misra said.

However, UPPCB officials said during the lockdown, the water quality of the river at all the locations was found under category ‘D’ which is useful for ‘propagation of wild life and fisheries’, still a far cry from category A, or fit for drinking after treatment.

“A study of tributaries of river Yamuna is also being done for the pre-lockdown and lockdown period,” an official of UPPCB, on condition of anonymity said.