A new report by the Central Pollution Control Board submitted to the National Green Tribunal has said that as per statistical analysis, the water quality during the recently-concluded Maha Kumbh in Prayagraj was fit for bathing.
The Central Pollution Control Board (CPCB) report said the statistical analysis was necessitated because of "variability of data" in the samples collected from the same locations across different dates and on different locations on the same day, because of which these did not reflect the "overall river water quality throughout the river stretch".
The report dated February 28 and uploaded on the tribunal's website on March 7 said the board had conducted water monitoring twice a week from January 12 onwards, including on auspicious bathing days, at five locations on Ganga river and two locations on Yamuna river.
"There is a significant variability in the values on various parameters, viz pH, dissolved oxygen (DO), biochemical oxygen demand (BOD) and fecal coliform count (FC) for the samples taken from the same location on different dates. The values of the afore-mentioned parameters also vary at different locations for the samples collected on the same day," the report said.
The DO or the amount of oxygen in water, BOD, which measures the amount of oxygen needed to break down organic matter in water, and FC, a marker of sewage contamination, are key indicators of water quality.
The report said that an expert committee examined the issue of "variability in data" and said that "the data represents a snapshot of water quality at a specific location and time and may vary significantly depending upon factors such as upstream anthropogenic activities (human actions), rate of flow, depth of sampling, time of sampling, river current and mixing of currents, sampling location and such other multiple factors".
"As a result, these values reflect water quality parameters at the exact time and place from where these water samples were collected, and may not fully represent the overall characteristics of the river, therefore, not necessarily reflecting the overall river water quality throughout the river stretch," it said.
The report also said that because of the variability, a statistical analysis of water quality data of various monitoring locations for the key parameters was undertaken from January 12 to February 22 at 10 locations of "mass bathing" and that 20 rounds of monitoring were done.
"It is submitted that as per the above-mentioned statistical analysis, the median value (central tendency of the data) of pH, DO, BOD and FC for the monitored stretches is within the respective criteria/permissible limits," the report noted.
According to the report, the median value for FC was 1,400 as compared to the permissible limit of 2,500 units per 100 ml, while the DO was 8.7 vis-a-vis the stipulated norm of being greater than 5 milligram per litre, and the BOD was 2.56 against the stipulated limit of less than or equal to 3 mg per litre.
On February 17, the CPCB had informed the tribunal through a report that various locations in Prayagraj during the Maha Kumbh were not conforming to the primary water quality for bathing with respect to the level of faecal coliform.
"The river water quality was not conforming to the primary water quality for bathing with respect to faecal coliform at all the monitored locations on various occasions.
"A large number of people bathe in the river at Prayagraj during the Maha Kumbh Mela, including on auspicious bathing days, which eventually leads to an increase in faecal concentration," the report had said.
At present, the matter has been posted for hearing on April 7.
Advocate Saurabh Tiwari appeared for the petitioner in the case.
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