Water quaity of Yamuna deteriorate sharply; Faecal Coliform levels jump to 92,000 units in December

New Delhi: Faecal coliform levels in the Yamuna, a key indicator of untreated sewage entering the river, rose sharply over a two-month period, according to the Delhi Pollution Control Committee’s (DPCC) monthly water quality reports for November and December 2025 released on Sunday, more than two months after the last disclosure.

The data shows faecal coliform levels increasing from 8,000 units per 100 ml in October to 24,000 units per 100 ml in November, before peaking at 92,000 units per 100 ml in December.

This is far above the safe limit of 2,500 units per 100 ml and the desired standard of 500 units per 100 ml. In October, when excess water was released upstream during Chhath Puja, pollution levels had been comparatively lower.

Despite the deterioration since October, the river remained significantly cleaner than during the same period last year. In December 2024, faecal coliform levels had touched 8.4 million units per 100 ml, while in November 2024 they stood at 7.9 million units per 100 ml.

Experts, however, flagged the steep year-on-year decline as improbable, noting that river flow is typically low during winter months, which usually leads to higher concentrations of pollutants.

The reports also highlight troubling trends in other pollution indicators. Biological oxygen demand (BOD), which reflects the amount of organic pollution in the water, was recorded at 25 mg per litre in October, rose to 33 mg per litre in November, and declined to 25 mg per litre in December. Even the lowest of these values is more than eight times the acceptable limit of 3 mg per litre.

Dissolved oxygen (DO), essential for sustaining aquatic life, showed wide fluctuations. In November, DO levels ranged between 0.5 mg per litre and 8.5 mg per litre, dropping to zero at two monitoring locations.

In December, levels ranged from 0.8 mg per litre to 8 mg per litre, again falling well short of the minimum required level of 5 mg per litre at several points.

By comparison, in December last year, BOD levels had reached 70 mg per litre, and while DO was within permissible limits at Palla and Wazirabad, it dropped to zero at six locations downstream. In November 2024, BOD stood at 54 mg per litre, with zero DO recorded at six locations below Wazirabad.

Water quality assessments are based on manual sampling at eight locations along the Delhi stretch of the Yamuna: Palla, Wazirabad, ISBT Kashmere Gate, ITO bridge, Nizamuddin bridge, Okhla barrage, Agra Canal, and Asgharpur, where the river exits the city.

The delayed release of the data follows a December 22 order by the National Green Tribunal directing the DPCC to place water quality data for the stretch between Wazirabad and Asgharpur on record.

Structural failur in clean Yamuna campaign:-Despite the completion of nine sewerage infrastructure projects under the Namami Gange Programme (NGP) and the utilisation of over ₹108 crore since January 2025, the Yamuna continues to face severe pollution due to a combination of structural, operational, and governance-related factors.

A key issue is that sewage generation in Delhi exceeds both installed and effectively utilised treatment capacity. While 1,268 million litres per day (MLD) of treatment capacity has been created on paper, not all sewage is being intercepted and conveyed to treatment plants.

Large volumes of wastewater continue to enter the river directly through nearly 20 major drains, many of which carry untreated or partially treated sewage, especially during low-flow winter months.

Operational inefficiencies further undermine the impact of existing infrastructure. Several sewage treatment plants (STPs) do not consistently meet discharge standards, particularly for faecal coliform and biological oxygen demand.

Inadequate maintenance, power outages, and outdated treatment technologies reduce real-world performance, meaning treated effluent often remains highly polluted when released into the river.

Another critical factor is the lack of sufficient freshwater flow in the Yamuna. During most of the year, especially after October, minimal water is released downstream of Wazirabad barrage.

With little dilution capacity, even treated effluent significantly degrades water quality. Experts note that without ensuring ecological flow, infrastructure investments alone cannot restore river health.

The rapid growth of unplanned and informal settlements also contributes to pollution. Many areas remain unsewered or poorly connected to the sewer network, leading to direct discharge of domestic waste into drains and the river.

Industrial effluents, though smaller in volume compared to sewage, add toxic loads due to weak monitoring and enforcement.

Governance and coordination gaps persist as responsibilities are split across multiple agencies, including the Delhi Jal Board, DPCC, municipal corporations, and central bodies. Delays in data disclosure, limited real-time monitoring, and weak accountability mechanisms make it difficult to assess outcomes and correct failures promptly.

Finally, river rejuvenation requires more than capital expenditure on treatment plants. Catchment management, drain remodelling, strict enforcement against illegal discharges, public participation, and continuous monitoring are essential. Without addressing these systemic issues, high financial investment alone is unlikely to translate into a visibly cleaner Yamuna.