Several dead fish have been discovered along the Yamuna River near Burari in north Delhi since the night of October 11, prompting worries about the river’s water quality and potential industrial pollution. Wildlife experts and activists have raised alarms, suggesting that untreated industrial effluents and low levels of dissolved oxygen may be contributing factors.

Wildlife conservationist Hemant Garg, who observed the dead fish, noted that the area is usually clean and is frequently visited for conservation activities. He mentioned that thousands of dead fish were seen upstream, specifically around shank numbers 10, 11, and 12. Garg emphasised the importance of monitoring this section of the river, as it serves as a drinking water source.

Ranjan Mukhia, a local boatman, reported a strong odour emanating from the water and indicated that the fish deaths are not confined to the Burari stretch. He stated that fellow boatmen upstream in Haryana have also reported similar incidents, highlighting the need for immediate action to remove the carcasses to prevent further pollution.

Possible Causes of Fish Mortality

Bhim Singh Rawat, a Yamuna activist and member of the South Asia Network on Dams, Rivers and People (SANDRP), pointed out that mass fish deaths are typically observed during the summer months when high temperatures lead to reduced dissolved oxygen levels. He expressed concern over the possibility of untreated industrial effluents being responsible for the current situation, citing specific drains from Panipat and Burari that may have discharged harmful substances.

Rawat also mentioned that the river’s flow has been restricted, which could exacerbate the ecological crisis. In light of these developments, Yamuna activist Pankaj Kumar has reached out to the Delhi Pollution Control Committee, urging immediate intervention. Kumar highlighted that fish mortality serves as a critical bio-indicator of severe ecological stress, with low dissolved oxygen and the presence of toxic industrial effluents being primary concerns.

In a post on X, the New Delhi Nature Society reported that hundreds, possibly thousands, of fish were found dead on October 14, with locals alleging that chemical waste discharged from Haryana could be a contributing factor. They also speculated whether the recent acid rain on October 12 could be linked to the incident.

Historical Context and Water Quality Data

This incident is not isolated; in May 2026, a similar occurrence was noted at Sanjay Lake in east Delhi amid a heatwave, attributed to high temperatures and concentrated pollutants. Earlier, in April 2026, thousands of dead fish were reported in Najafgarh drain, with industrial effluents from Haryana suspected as the cause. Previous incidents in May 2025 and July 2024 also recorded significant fish mortality along the Yamuna banks near Burari.

The monthly water quality report for September indicates that, despite the monsoon season, the river stretch in Delhi has not shown significant improvement in pollutant levels. A comparison of water quality reports from September 2025 and September 2026 reveals alarming increases in biochemical oxygen demand (BOD) and faecal coliform levels at various locations along the river.

At Palla, faecal coliform levels rose from 790 units last year to 1,100 units this year. At the ISBT Bridge, levels surged from 2,800 units to 35,000 units, while Okhla barrage recorded a rise from 3,500 units to 21,000 units. These figures highlight the presence of untreated sewage, as the acceptable limit for faecal coliform should ideally be below 500 units. Additionally, BOD and chemical oxygen demand (COD) levels have also seen significant increases, raising further concerns about the river’s ecological health.

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