Yamuna's water quality hits new low: BOD levels 'dangerously' high - 'not enough fresh water flow'

Yamuna river froth

The quality of water in the Yamuna River has severely deteriorated, with Biological Oxygen Demand (BOD) levels rising far above the safe limit, according to a recent report by the Delhi Pollution Control Committee (DPCC).

The report, titled ‘Progress in Rejuvenation of the River Yamuna’, includes BOD data collected between January 2023 and March 2025 from key locations in Delhi.

BOD indicates the quantity of oxygen required by microorganisms to decompose organic substances present in the water. Elevated BOD levels signify that the water is considerably contaminated and unfit for aquatic organisms. The Central Pollution Control Board (CPCB) states that BOD levels in a river must not go above 3 milligrams per litre (mg/l).

The DPCC monitored water quality at three major points: the outfall of the Najafgarh drain, ISBT Kashmere Gate, and the area downstream of the Shahdara drain near Kalindi Kunj. The data shows that BOD levels in these locations are dangerously high.

In January 2023, BOD was measured at 53 mg/l in the Najafgarh drain. It came down to 42 mg/l in August 2023 but surged once more to 64 mg/l in both February and October 2024. The maximum amount noted was 90 mg/l in February 2025, 30 times greater than the permissible limit.

The most concerning statistics emerged from downstream of the Shahdara drain, near the point where the Yamuna leaves Delhi. In this instance, the BOD concentration increased from 56 mg/l in January 2023 to an alarming 127 mg/l in January 2025, marking the highest level documented over these three years.

According to a report by Hindustan Times, the worsening condition is due to two main reasons: low water flow in the river and stagnant development of sewage and industrial waste treatment systems. “The river hasn’t had enough fresh rainwater to dilute pollutants since the last monsoon, and that the capacity of sewage and effluent treatment plants hasn’t improved in the past two years,” Bhim Singh Rawat, a member of the South Asia Network on Dams, Rivers and People (SANDRP) was quoted by HT as saying.

Meanwhile, the Delhi Jal Board (DJB) is working on constructing 12 new sewage treatment plants (STPs) across the city. This includes a large 13-million-gallon-per-day (MGD) plant in Chhawla and 11 smaller decentralised STPs with new pumping stations. These projects aim to reduce the volume of untreated sewage entering the Yamuna, particularly from the Najafgarh drain.

Currently, Delhi has 37 STPs with a total treatment capacity of 764 MGD. However, the city produces around 792 MGD of sewage daily, leaving a gap that leads to untreated waste being dumped directly into the river.