The big picture

During the 2025 Delhi state assembly elections, the pollution of the Yamuna emerged as a significant concern for voters. Most experts wrote articles that primarily focused on controlling pollution in the river, while other connected issues, such as the Yamuna’s flow and the need for a comprehensive Delhi water policy, found only brief mentions.

A river is a hydrological system that cannot be divided along administrative boundaries, whether longitudinally or laterally. Longitudinal connectivity emphasises the river’s connection with upstream and downstream points, while lateral connectivity focuses on its interaction with floodplains, tributaries and river ecosystems such as wetlands, all of which are essential for maintaining the health and function of the entire river ecosystem. Additionally, there is the vertical aspect to consider—the fragile connection between surface water and groundwater, with groundwater playing a key role in maintaining the river’s base flow. This connection is particularly vital during dry periods to sustain river water levels and aquatic ecosystems.

Viewing a river in a fragmented manner, defined by administrative boundaries, and focusing only on issues like pollution or governance failures does a disservice to the river and leaves the broader problem unresolved. Understanding the many facets of river management—specifically the environmental flow requirements, pollution control, water demand management and the impacts of climate change—can pave the way for long-term solutions.

Restoring flow

A river like the Yamuna serves many roles—hydrological, ecological, social and cultural. At the heart of all these is its fundamental right to flow, which is critical for recharging groundwater, transporting sediment, supporting biodiversity and sustaining riparian ecosystems. Over the decades, the average flow of the river, particularly downstream of the Hathnikund Barrage System in Haryana’s Yamuna Nagar district, has significantly reduced. Unsustainable water extraction and diversion to meet the demands of hydropower, irrigation, industry and potable water leaves the river with little to no flow for nearly nine months a year. Media and government reports say nine such structures have already been built, six are under construction and 31 projects have been proposed in the Yamuna basin.

The 1994 agreement among the five Yamuna basin states—Uttar Pradesh (then including Uttarakhand), Haryana, Rajasthan, Himachal Pradesh and the National Capital Territory of Delhi—established the Upper Yamuna River Board (UYRB), which lapsed last year but had mandated an environmental flow of 10 cubic metres per second (cumecs) downstream of the Hathnikund Barrage system. However, this flow is not only poorly enforced but also highly inadequate, as much of it evaporates or percolates before reaching Delhi. A 2019 study by the National Institute of Hydrology, Roorkee, Uttarakhand, concluded that the current flow is insufficient and recommended increasing it to 23 cumecs. A review of water allocation among the party states under UYRB is scheduled for this year.

As population and economic growth continue to rise, there has been an exponential increase in reliance on water storage and abstraction structures, driven by the belief that allowing untapped water to flow into the sea is wasteful. As a result, rivers are left with insufficient water. This also diminishes the river’s self-purification capacity, which is crucial in cities like Delhi, where pollution levels are among the highest. Furthermore, rampant encroachment of floodplains, sand mining from riverbeds, and over-extraction of groundwater reduce the flow in the river. Although laws like the River Ganga (Rejuvenation, Protection, and Management) Authorities Order, 2016—which prohibits construction on the floodplains of the Ganga and its tributaries—and the Sustainable Sand Management Guidelines, 2016, are in place, they have not led to major improvements in river flow, as the real challenge lies in their enforcement.

Restoring environmental flow in the Yamuna, including in Delhi, needs a comprehensive approach to watershed restoration. This would entail safeguarding the pristine catchments that currently exist, while progressively restoring the de-graded ones, including the rejuvenation of the river’s tributaries. Key actions would include mindful rewilding, careful planning of water abstraction structures and even the demolition of aging or unnecessary structures. Strict enforcement of laws related to floodplains, sand mining and groundwater extraction will be critical to this restoration.

Tackling pollution

The Yamuna in Delhi, deprived of its natural flow, is heavily polluted with wastewater and solid waste from the city. Despite comprising just 2 per cent of the river’s total catchment area, the National Capital Territory of Delhi contributes 79 per cent to the river’s overall pollution, making this section of the Yamuna the most polluted. The main source of pollution in the Yamuna in Delhi is domestic waste, accounting for about 85 per cent of the total pollution. Other major contributors include industrial effluents, agricultural runoff, solid waste and microplastics.

A recent parliamentary panel highlighted that Dissolved Oxygen (DO), which reflects a river’s ability to sustain life, is virtually absent in the Delhi stretch of the Yamuna. The required standard for DO is greater than 5 mg/l, but levels are far below this threshold. Inadequate treatment capacity, sewage treatment plants (STPs) not operating at full efficiency, poorly maintained sewer systems, and inadequate sewage interception for treatment contribute to the poor water quality.

Of the 790 million gallons a day (MGD; 1 gallon equals 3.8 litres) of sewage generated in Delhi, 550-600 MGD is treated in STPs. But most of the treated wastewater is discharged back into drains, where it mixes with untreated water from unauthorised settlements before flowing into the river through 22 major drains. Of the 37 STPs in Delhi, 21 failed to meet the required standards across various parameters last year. Additionally, of the 33 industrial areas in Delhi, 16 lack Common Effluent Treatment Plants (CETPs).

To effectively address pollution in the Yamuna, it is vital to enhance the capacity of existing STPs, add new STPs and CETPs, closely monitor the performance of the STPs and CETPs, implement efficient solid waste management, improve sewage interception, regulate desludging tankers in unsewered areas, desludge the river bed, reconstruct and rehabilitate the sewer system, promote eco-friendly detergents and explore nature-based solutions for water purification.

Managing demand

Delhi heavily relies on external sources to meet its massive water demand of approximately 1,290 MGD. According to the Delhi Jal Board (DJB), the city’s raw water supply comes from four main sources: 40 per cent from the Yamuna, 25 per cent from the Ganga, 22 per cent from the Bhakra Nangal Dam, and the remaining 13 per cent from subsurface sources like tube wells. This water is treated at nine water treatment plants, with a supply ranging from 977 MGD to 993 MGD, which still falls short of the demand. While significant efforts have been made to increase the water supply to the city, little has been done to manage the growing demand.

Demand management can be achieved through innovative strategies such as gradually lowering domestic water supply norms, promoting water-saving devices, recycling and reusing treated wastewater, enhancing rainwater harvesting across public and private spaces, and addressing freshwater losses in aging water infrastructure. To ensure the effectiveness of these initiatives, workshops should be conducted to educate citizens on the benefits for the river and their own well-being.

Global warming is causing glaciers—which provide crucial water to rivers during dry months—to shrink. This loss threatens to turn major rivers like the Ganga and the Yamuna into seasonal rivers in the coming decades. Tackling the impacts of climate change needs global efforts to reduce carbon emissions as well as local measures such as catchment restoration and water harvesting.

A comprehensive approach that addresses all facets of river management is essential to tackle the Yamuna issue. Experts advocate the need of a comprehensive water policy for Delhi to navigate these challenges. In 2017, the Indian National Trust for Art and Cultural Heritage (INTACH), New Delhi, prepared a water policy for DJB, which could serve as a starting point. Only through holistic, integrated efforts can the Yamuna truly flow.

(Ritu Rao is a consultant with Indian National Trust for Art and Cultural Heritage, New Delhi, working on river-related projects)

This article was originally published in the June 16-30, 2025 print edition of Down To Earth