Faecal contamination, a key indicator of untreated sewage, peaked at 1.5 million MPN/100ml by the time the river exited Delhi, far above the acceptable limit of 500 units for outdoor bathing.
Yamuna remains severely polluted despite partial improvements, says April DPCC report
The latest assessment by the Delhi Pollution Control Committee (DPCC) reveals that the Yamuna river remains heavily polluted, with certain parameters worsening in April. Faecal contamination, a key indicator of untreated sewage, peaked at 1.5 million MPN/100ml by the time the river exited Delhi, far above the acceptable limit of 500 units for outdoor bathing.
This marks an increase from 1.3 million MPN/100ml in March 2025 and a sharp contrast to April 2024 levels, which were recorded at 430,000 units.
Sewage treatment plants underperforming
In a separate report, the DPCC found that 16 out of Delhi Jal Board’s 37 sewage treatment plants (STPs) failed to meet prescribed standards in April. These plants are critical to maintaining water quality, and their poor performance is directly linked to pollution levels in the river. The discharge of untreated or partially treated sewage into the Yamuna, especially via major drains like the Najafgarh and Shahadara, continues to be one of the biggest sources of contamination.
Biochemical oxygen demand shows slight improvement
The river’s biochemical oxygen demand (BOD), which indicates the amount of oxygen needed to break down organic matter, saw a marginal improvement. In April, BOD levels dropped to 56 mg/l from 70 mg/l in March. While this shows a modest positive trend, the levels remain far above acceptable limits, indicating the river water’s poor self-purifying capacity.
Phosphate levels decline significantly
One of the more encouraging findings in the April assessment was a drop in phosphate concentrations. Previously linked to detergent and textile industry discharge, phosphate levels peaked at 5.77 mg/l in March but dropped to 1.92 mg/l in April. This decline marks a significant improvement, although pollution levels continue rising downstream from the Nizamuddin Bridge.
Despite minor improvements in some areas, the dissolved oxygen (DO) level — a key indicator of aquatic life — remained at zero in April, as has been the case for years. This continued absence of DO suggests that the river remains biologically dead as it leaves Delhi.
Though there are signs of slight progress in phosphate and BOD levels, the overall condition of the Yamuna remains poor. Rising faecal contamination, underperforming STPs and persistently dead water quality highlight ongoing challenges in the effort to clean the river. The DPCC report underlines the urgent need for sustained interventions and stricter pollution control measures.