Yamuna’s water still worsening, now 42 times worse than permitted limit: DPCC

BOD is the amount of dissolved oxygen required by microorganisms to decompose organic matter in the water body.

Water quality in the Yamuna river has worsened, with the biological oxygen demand (BOD) levels spiking to over 42 times the permissible standard, a latest report from the Delhi Pollution Control Committee (DPCC) showed. The report, titled “Progress in Rejuvenation of the River Yamuna”, has BOD levels from three prominent locations in the river between January 2023 and March 2025.

The worst readings were recorded downstream of the Shahdara drain, where the river is close to exiting Delhi. (HT Archive)

BOD is the amount of dissolved oxygen required by microorganisms to decompose organic matter in the water body. It is an indicator of the water body’s ability to sustain aquatic life alongside dissolved oxygen (DO) and should not be more than 3mg/l (milligrams per litre) in case of a river, as per Central Pollution Control Board (CPCB).

The DPCC report showed data from the outfall of Najafgarh drain, ISBT Kashmere Gate, and from the downstream of Shahdara drain near Kalindi Kunj. While the report assesses progress of existing projects in the Yamuna, it also carries out a monthly assessment of the river’s water quality from eight locations, as mandated by the National Green Tribunal (NGT).

The data showed the BOD was 53 mg/l at Najafgarh drain on January 2023 and improved to 42 mg/l in August 2023. However, the reading shot up to 64 mg/l twice – in February 2024 and October 2024 – before touching a peak of 90mg/l on February 2025, the highest value in the last two years, the report mentioned.

The worst readings were recorded downstream of the Shahdara drain, where the river is close to exiting Delhi. While the BOD there was 56 mg/l in January 2023, it touched a peak of 127 mg/l in January 2025 – this location’s the highest reading in the last three years.

Meanwhile, experts said the spike is likely due to a combination of low environmental flow in the river and no change in the existing sewage and effluent treatment plants in the city. “The river’s flow has been reducing since last monsoon as there has not been enough non-seasonal rainfall in Delhi or in the higher reaches. Normally, the rain dilutes the river and the pollution. At the same time, we have not seen any improvement in the quantum of sewage or effluents being released into the Yamuna. Our STPs (sewage treatment plants) and ETPs (effluent treatment plants) are at the same level as they were two years ago,” Bhim Singh Rawat, an activist for Yamuna and member of the South Asia Network on Dams, Rivers and People (SANDRP), said.

HT reported on Tuesday that the Delhi Jal Board (DJB) is working on developing 12 new STPs in the Capital with the aim to reduce untreated sewage being dumped from the Najafgarh drain into the Yamuna river. This included work on a 13MGD (million gallons per day) capacity wastewater treatment plant in southwest Delhi’s Chhawla along with 11 units of smaller decentralised STPs (DSTPs) and pumping stations.

Presently, Delhi has 37 STPs, with a combined capacity of 764MGD. Delhi generates around 792MGD of sewage every day.