In a bid to improve the Yamuna’s water quality, the Delhi government will release treated wastewater from the Okhla sewage treatment plant (STP) — Asia’s largest — to boost the river’s environmental flow (e-flow). The plan will discharge 5.69 cubic metres per second (cumecs) of treated effluent into the river, aiming to address its critically low flow levels and pollution load.

Delhi’s stretch of the Yamuna requires a minimum 23 cumecs of e-flow to sustain ecological health, according to expert committees and parliamentary panels. Currently, it flows at just 10 cumecs. The additional treated water will provide partial relief to heavily polluted areas near Okhla and Kalindi Kunj, officials said.

The Okhla STP, which became fully operational in April 2024, treats 564 million litres per day (MLD) of wastewater. A 2,800 mm pipeline, being laid using micro tunnelling technology, will carry the treated water to the Abul Fazal drain, which discharges downstream of the Okhla barrage. Of the required 225-metre stretch, 100 metres have already been laid along Jasola Road.

Delayed due to clearance issues with the Uttar Pradesh Irrigation Department, the pipeline project is now expected to be completed by end-2025, with discharge to begin by February 2026.

The initiative, a joint effort of the Delhi Jal Board (DJB) and National Mission for Clean Ganga (NMCG), is intended to dilute pollutants, reduce frothing and foul odours, and improve ecological balance in the Yamuna.

However, experts have cautioned that this step alone is not enough. Bhim Singh Rawat, a member of the South Asia Network on Dams, Rivers and People (SANDRP), said, “The Yamuna currently acts like a drain. Cleaner discharge may help, but the real solution lies in stopping raw sewage discharge altogether.”

Rawat also emphasised the importance of strict water quality control and called for a comprehensive policy to use treated water for non-potable purposes across Delhi, ensuring effective use of recycled water and reducing waste.

This move represents a partial but important step in Delhi’s broader efforts to rejuvenate the Yamuna, which remains one of the most polluted rivers in India.