New Delhi: A report by the Central Pollution Control Board (CPCB) submitted to the National Green Tribunal (NGT) has found that water quality during the recently concluded Maha Kumbh in Prayagraj was fit for bathing, as per statistical analysis.

Faecal coliform—microbes from human and animal excreta—had earlier been a major concern. On February 17, CPCB had informed the tribunal that several locations in Prayagraj did not meet primary water quality standards for bathing due to elevated faecal coliform levels. The report had stated, “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.” It attributed the increase in faecal contamination to the large number of devotees bathing in the river, especially on auspicious bathing days.

Statistical analysis conducted due to fluctuating water quality parameters
The latest CPCB report, dated February 28 and uploaded on the tribunal’s website on March 7, noted that a statistical approach was necessary due to "variability of data" in water samples collected from the same locations on different dates and from different locations on the same day. This variability, it said, did not reflect the overall river water quality throughout the river stretch.

Monitoring conducted twice a week at multiple locations
The CPCB conducted water monitoring twice a week from January 12 onwards, including on auspicious bathing days, at five locations on the Ganga and two locations on the Yamuna.

"There is a significant variability in the values on various parameters, viz pH, dissolved oxygen (DO), biochemical oxygen demand (BOD) and faecal coliform count (FC) for the samples taken from the same location on different dates," the report noted. It further highlighted that these values also fluctuated across different locations on the same day. It may be noted that 

DO, which measures oxygen levels in water, BOD, indicating organic matter decomposition, and FC, a marker of sewage contamination, are key indicators of water quality.

Expert panel assesses data fluctuations
An expert committee examined the variability in data, attributing it to factors such as upstream human activities, water flow rate, sampling depth, river currents, and mixing patterns.

"The data represents a snapshot of water quality at a specific location and time and may vary significantly depending upon multiple factors," the report stated, adding that the values recorded might not fully represent the overall river water quality.

Statistical findings indicate water quality within permissible limits
Given the inconsistencies, the CPCB undertook a statistical analysis of key parameters across 10 mass bathing locations from January 12 to February 22, conducting 20 rounds of monitoring.

"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.

The median FC value stood at 1,400 per 100 ml, well within the permissible limit of 2,500 units. DO levels were recorded at 8.7 mg per litre, surpassing the minimum requirement of 5 mg per litre, while BOD measured 2.56 mg per litre, remaining within the allowable limit of 3 mg per litre.

Previous report flagged non-compliance on faecal coliform levels
On February 17, CPCB had informed the NGT that several locations in Prayagraj during the Maha Kumbh did not meet primary water quality standards for bathing due to elevated faecal coliform levels.

"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," the report had said. It attributed the rise in faecal contamination to the large number of devotees bathing in the river, especially on auspicious bathing days.

Tribunal to hear the matter on April 7
The NGT has scheduled the next hearing for April 7. Advocate Saurabh Tiwari appeared for the petitioner in the case.