The Ganga, worshipped for centuries as India’s lifeline, is now fighting a different kind of battle, not against drying up, but against pollution. A recent study titled, “Holistic analysis of Ganga basin water quality: a statistical approach with WQI, HMCI, HMQI and HRI indices,” was conducted in the Prayagraj region, where the Ganga meets the Yamuna. It has revealed worrying levels of contamination that put both people and the river’s ecosystem at risk.
The study led by Dipti Tiwari and team examined water quality across eight locations along a 55-kilometre stretch of the Ganga and Yamuna between 2021 and 2022. Researchers chose sites that capture the full range of influences on the rivers from the spiritually significant Sangam, to areas affected by urban discharges (Sobatiyabagh), agricultural runoff (Draupadi Ghat), and cremation ghats (Rasoolabad and Daraganj).
Over 120 water samples were collected and analysed using a mix of conventional and advanced methods such as the Water Quality Index (WQI), Heavy Metal Contamination Index (HMCI), Heavy Metal Quality Index (HMQI), and Human Health Risk Index (HRI). Together, these offered a complete picture of the river’s condition.
The findings reveal a troubling reality. The Ganga, once a symbol of purity, is now burdened with waste from cities, factories, and farmlands. What flows through Prayagraj today carries the story of how rapid development has outpaced environmental care.
Water Quality Index: The WQI ratings showed a grim scenario: while some sites like Sangam and Rasoolabad were deemed to have “excellent” or “good” water quality, others such as Draupadi Ghat (S2) and Yamuna’s Arail Kachar (S8) registered WQI values exceeding 50, categorising them as “poor”. These ratings signal water that is “threatened or impaired”, unsuitable for drinking, risky for bathing, and hazardous for aquatic life.
Heavy Metal Contamination and Quality Index (HMCI & HMQI): Across all eight sites, HMCI values exceeded 700, far surpassing the safety threshold of 100. Particularly high contamination was noted at S4 (Daraganj) and S8 (Yamuna), where industrial discharge and untreated sewage were rampant. The HMQI results corroborated this, showing heavy metal loadings, especially of lead (Pb) and cadmium (Cd), well beyond WHO and BIS safety limits. These metals are known for their carcinogenic and neurotoxic properties.
Health Risk Index (HRI): The health implications are staggering. Calculations of daily metal intake and oral reference doses revealed HRI values >1 for both Pb and Cd at multiple sites—marking them as hazardous for chronic consumption. The toxicity of these metals manifests in neurological disorders, kidney failure, reproductive harm, and even cancer. As a consequence, millions living along these banks, drawing water directly for household use, face a silent but growing public health crisis.
Urban discharge and open defecation: Only 42.8% of Prayagraj’s 208 MLD sewage is treated before entering the river. The rest, alongside solid waste, carcasses, and untreated effluents, flows directly into the water. Draupadi Ghat and Daraganj proximal to high-density settlements—emerged as pollution hotspots.
Industrial effluents: Prayagraj hosts over 10,000 registered industrial units, ranging from textiles and chemicals to rubber and metal works. Sites like Sobatiyabagh (S1) and Daraganj (S4), surrounded by such industries, showed elevated levels of lead, cadmium, and chromium, indicating direct contamination via discharge or runoff.
Agricultural runoff: High concentrations of potassium, sodium, phosphate, and nitrate were found near agricultural areas such as Draupadi Ghat (S2) and Sangam (S5), pointing to the role of fertilisers and pesticides. These nutrients not only fuel eutrophication but also interact chemically with metals, altering their solubility and mobility.
Cremation and ritual practices: Sites like Rasoolabad and Chatnag are used extensively for cremation and religious ceremonies. Human remains, ashes, and ceremonial substances often rich in organic and inorganic materials add to the biological and chemical load of the rivers.
Using Land Use and Land Cover (LULC) data from ESRI Sentinel-2 imagery, the study found clear spatial patterns. Areas with higher urban and industrial land cover recorded greater levels of electrical conductivity, dissolved solids, and heavy metals. In contrast, ghats with forested or green buffers, such as Chatnag (S7), showed better resilience and cleaner water — acting as natural filters. This insight highlights why land-use planning and green zones are essential for protecting river ecosystems.
The study used Principal Component Analysis (PCA) and Cluster Analysis to decode pollution patterns. PCA isolated two main pollutant profiles one dominated by ionic contaminants (TDS, EC, Cl−, SO₄²⁻), and the other by biological oxygen demand and sodium loadings. Cluster Analysis divided the sites into three groups:
Cluster 1: (S1, S3, S4, S7) – Urban/industrial impact
Cluster 2: (S5, S6) – Agricultural influence
Cluster 3: (S2, S8) – Mixed and extreme pollution scenarios
This classification allows for targeted interventions depending on the dominant pressure at each cluster.
Results were compared with drinking water standards established by the Bureau of Indian Standards (BIS) and the World Health Organization (WHO).
The findings offer both a warning and a roadmap. The Ganga and Yamuna in Prayagraj are not just religious and cultural icons, they are public health concerns, biodiversity hotspots, and economic engines. Water quality degradation has serious consequences for health, the environment, and livelihoods. Poor water quality can lead to a rise in health risk index (HRI) values, which in the future can result in an increase of kidney disease, neurological disorders, and cancer. It also harms the environment by causing eutrophication, reducing dissolved oxygen, and increasing metal toxicity, all of which disrupt aquatic life. Lastly, it threatens the livelihoods of people who depend on rivers, such as fishers, farmers, and pilgrims, who face declining returns and increasing risks.
Strengthen sewage treatment: Increase STP coverage to 100%, ensure compliance with CPCB discharge standards.
Regulate industry: Enforce Zero Liquid Discharge (ZLD) in industrial hotspots like Sobatiyabagh and Daraganj.
Green buffer zones: Protect and expand riparian vegetation buffers to filter runoff.
Land use zoning: Align LULC-based zoning with pollution potential to control future expansion of high-risk activities.
Public health monitoring: Set up regular screening of communities along S2 and S8 for heavy metal exposure.
Behavioural interventions: Promote eco-sensitive ritual practices, including cremation and idol immersion alternatives.
This study results consistently showed that water quality at several sites is far below desirable standards. At Draupadi Ghat (S2) and Arail Kachar (S8), WQI values of 51.97 and 66.98 indicated poor quality. Heavy metal contamination was severe, with HMCI values of 806.01 at Sobatiya Bagh (S1) and 981.33 at Arail Kachar (S8), reflecting high levels of lead (Pb) and cadmium (Cd). The HRI confirmed elevated health risks at these sites.
High concentrations of sodium and chloride further revealed pollution from agricultural runoff, sewage, industrial effluents, and improper waste disposal, alongside religious activities such as mass bathing during Kumbh Mela. These stressors threaten aquatic biodiversity, human health, and sectors like agriculture, fisheries, and tourism that depend on the rivers.
The findings underscore the urgent need for remediation, stricter regulation of industrial effluents, and continuous monitoring of water quality. Water treatment for drinking and irrigation may be necessary to protect communities. Without timely action, the cultural, ecological, and economic lifelines of the Ganga and Yamuna will remain at risk.
The story of the Ganga and Yamuna in Prayagraj is not just about data points and indices—it is about what we choose to see and what we choose to ignore. Behind every number lies a mother fetching water she no longer trusts, a child bathing in a river that once symbolised purity, and an ecosystem slowly gasping for breath.
Restoring these rivers is not only an act of environmental repair; it is an act of remembering who we are. The Ganga has always been more than a waterway—it has been a mirror reflecting the health of our civilization. When that reflection turns murky, it asks us to look inward and ask: how did a river worshipped as sacred come to carry the weight of our neglect? The time for care and renewal is now, before reverence becomes memory and the river’s flow, a whisper of what it once was.