Slugfest shines spotlight on a key water pollutant in Yamuna

While the Yamuna is polluted when it enters the Capital from the north, it leaves the city in significantly worse shape – Delhi contributes to 76% of the river’s overall pollution.

The Aam Aadmi Party (AAP) has alleged that the Bharatiya Janata Party (BJP)-led Haryana government is poisoning the Yamuna’s waters, triggering a fresh flashpoint in the acrid Delhi elections campaign. But the claim has also turned the spotlight on a real problem – severely excessive ammonia levels in the Yamuna, especially in its stretch through the National Capital Region (NCR).

Ammonia levels usually rise between December and March, when the river’s flow begins to slow down after the monsoon’s effects begin to recede. (HT PHOTO)

Data and records from state agencies suggest that though Haryana does release water laden with ammonia into Delhi to an extent, this is largely due to systemic chinks in the region’s drainage networks and not a deliberate ploy. Further, while the Yamuna is polluted when it enters the Capital from the north, it leaves the city in significantly worse shape – Delhi contributes to 76% of the river’s overall pollution.

Experts and officials underscored that ammonia spikes (where its concentration crosses 1 part per million, or ppm) in Delhi’s water are regular and cyclical – the city has between 15 and 22 such episodes every year. Ammonia levels usually rise between December and March, when the river’s flow begins to slow down after the monsoon’s effects begin to recede.

To this end, the city’s water supply is currently dealing with the year’s first such ammonia spike, said an official of the Delhi Jal Board (DJB). This has led to production at two key treatment plants – at Wazirabad and Chandrawal – being curtailed because the plants can’t handle ammonia above a certain threshold.

“Our treatment plants use chlorination to treat the ammonia and they have the capacity to treat up to 1ppm ammoniacal nitrogen. Chlorination beyond these levels leads to generation of toxic chloramines. So ,the plant production is curtailed and the water is diluted from other sources like Munak canal,” the official said.

Data from the DJB quality control department at Wazirabad shows that ammonia levels in the river between December 2024 and January 2025 have been above 3ppm on 39 of 58 days.

These periodic spikes have long been a point of contention between the Delhi and Haryana governments. DJB argues that Haryana allows pollutants, including ammonia-based chemicals, dyes, chlorides and untreated chemicals to flow into the river from the Panipat industrial drain, 60km upstream of Palla on Delhi’s northern periphery, where the river enters the city.

DJB has also blamed the state for allowing industrial waste to mix into the water in Sonepat, where two canals carrying freshwater and industrial waste run parallel to each other.

Haryana, on its part, has denied these claims and insisted there are no pollution leaks in its industrial areas.

A DJB official said Haryana is working on laying a pipeline to prevent this intermixing, following a 2023 National Green Tribunal (NGT) order.

Industrial units in Haryana play their part in sullying the Yamuna’s waters, Delhi does far worse. Several experts have called the stretch of the Yamuna through Delhi a “dead river”.

The real degradation of the water begins after Wazirabad, when the Najafgarh drain – the biggest source of pollution for the Yamuna – meets the river.

Over its harrowing 22km journey through the national capital, the Yamuna meets an open drain roughly every 1.2km.

The Delhi Pollution Control Committee (DPCC) picks up water samples from the Yamuna at eight spots every month, checking them for a range of pollutants – like BOD, COD, dissolved oxygen (DO) and faecal matter. The findings from these collections underscore the acerbic effects Delhi has on the Yamuna.

DPCC data from December shows that DO – an indicator of the actual oxygen available in the water, essential for aquatic life – practically vanishes beyond Wazirabad. It was 6.1 mg/l at Palla, well within the Central Pollution Control Board’s (CPCB) 5 mg/l threshold.

This level drops to 5.3mg/l at Wazirabad, before becoming zero at ISBT bridge. It then remains zero for the rest of its journey through Delhi, leaving the city with no dissolved oxygen.

Bhim Singh Rawat, member of the South Asia Network on Dams, Rivers and People (SANDRP), said the frequent ammonia spikes in the river were on account of untreated effluents finding their way downstream from Haryana to Wazirabad.

“We know of drain number six in Sonepat and drain number two in Panipat, which frequently bring untreated effluents into the Yamuna. This leads to a spike in the ammonia content and the only solution is to crackdown on the source of these effluents.,” he said.

Referring to the Yamuna in Delhi as a “dead” river, Rawat said DO levels turning nil was a clear indicator of that.

“It shows no aquatic life can survive this stretch of the river and the solution remains simple. One, to trap sewage and connect them to sewage treatment plants. Secondly, the environmental or e-flow of the river needs to be increased. With increased flow, pollutants will naturally be flushed out to a large extent,” he said.

Faecal coliform levels are just as grim. The December data shows the faecal coliform touched readings of 8.4 million units/100ml at Asgarpur, where the river exits the Capital.

So, even as an ugly water war plays out between the BJP and AAP, data proves that a once-essential waterway, around which a thriving civilisation bloomed, dies a slow death for every inch that it passes through the city.