Yamuna River in Delhi Reaches Cleanest Levels in a Decade Amid Flooding

According to the latest monthly report from the Delhi Pollution Control Committee (DPCC), the water quality of the Yamuna River in Delhi reached its cleanest levels since 2013 in September 2025. Experts have credited this rare improvement to the river being in spate during recent flooding, which flushed out pollutants and diluted sewage.

The September data stands out as the most dramatic improvement in Yamuna's water quality in the last decade. Faecal coliform, a key marker of sewage contamination, dropped to just 3,500 most probable number (MPN)/100 ml at the Okhla barrage, close to the permissible limit of 2,500. This is a significant improvement from the 54,000 units recorded last month and the staggering 9.2 million units seen in July.

Dissolved oxygen (DO), which typically disappears downstream of Wazirabad, remained between 3.7 mg/l and 5.1 mg/l, with 5 mg/l being the minimum needed to sustain aquatic life. Biological oxygen demand (BOD), another critical indicator, also improved significantly, dropping to 13.5 mg/l at the Okhla barrage, down from 24 mg/l in August and 70 mg/l in July.

Experts attribute this improvement to Delhi experiencing its third-highest Yamuna level on record on September 4, at 207.48 metres. The high water levels diluted pollutants, while flood-control measures meant many drains were shut to prevent backflow, further reducing sewage entering the system.

However, the experts caution that this improvement is likely to be short-lived. Once the flood flow reduces, the river's pollutants are expected to dominate again, highlighting the need for long-term solutions to tackle the Yamuna's chronic pollution issues.