Assessment of Water Quality Index of the Yamuna River - Delhi, India

Abstract

The Yamuna River traverses approximately 22 km through the National Capital Territory of Delhi, receiving enormous quantities of domestic sewage, industrial effluents, and urban runoff. Despite its ecological and cultural significance, the Delhi stretch contributes nearly 75–80% of the river\'s total pollution load. This study assesses the Water Quality Index (WQI) of the Yamuna River across six strategically selected sampling stations — Signature Bridge, Majnu Ka Tilla, Shastri Park, Wazirabad, Budh Vihar, and Yamuna Bazar — using the Weighted Arithmetic Index method. Key physico-chemical parameters including pH, dissolved oxygen (DO), biochemical oxygen demand (BOD?), total dissolved solids (TDS), electrical conductivity (EC), chloride, turbidity, and total hardness were measured during both pre-monsoon and post-monsoon seasons (2024). WQI values ranged from 78 (post-monsoon, Signature Bridge) to 142 (pre-monsoon, Budh Vihar), placing all stations in the \'poor\' to \'unsuitable for drinking\' categories. The findings underscore the urgent need for comprehensive wastewater treatment infrastructure, ecological flow restoration, and multi-stakeholder governance reform.

Introduction

The study examines the water quality of the Yamuna River in Delhi, a highly polluted 22 km stretch that receives a large proportion of the river’s total pollution load due to untreated sewage, industrial effluents, and urban runoff.

Six monitoring stations from upstream (Wazirabad) to downstream (Yamuna Bazar) were analyzed during pre-monsoon and post-monsoon seasons (2024). Key physico-chemical parameters such as pH, DO, BOD, COD, TDS, EC, turbidity, chloride, and hardness were measured using standard APHA and BIS methods.

Results show severe pollution across all stations, especially downstream areas like Budh Vihar and Yamuna Bazar, where dissolved oxygen is critically low and organic pollution (BOD and COD) is very high. Pre-monsoon conditions are the worst due to low river flow, while post-monsoon rainfall provides some dilution but does not restore safe water quality.

The Water Quality Index (WQI) indicates that:

• All stations are polluted beyond drinking standards
• Pre-monsoon WQI ranges from 98 to 142, and post-monsoon from 78 to 115
• Most sites fall into the “Very Poor” or “Unsuitable for drinking” categories

Conclusion

This study provides a spatially resolved, seasonally differentiated assessment of Yamuna River water quality across the Delhi region using the Weighted Arithmetic WQI framework. The principal conclusions are: 1) Pervasive and severe pollution: All six sampling stations recorded WQI values above 78, placing the entire Delhi stretch in the \'Poor\' to \'Highly Polluted\' classification. No station met the criteria for water safe for direct human use under any season. 2) Downstream intensification: WQI deteriorated progressively from upstream (Wazirabad, Signature Bridge) to downstream (Budh Vihar, Yamuna Bazar), consistent with cumulative sewage loading from over 22 major drains and the reduction in the river\'s hydraulic capacity to dilute and re-aerate. 3) Monsoon provides partial, temporary relief: Post-monsoon WQI values improved by 16–28% relative to pre-monsoon, driven by rainfall dilution of ionic constituents. However, this improvement was insufficient to shift any sta to an acceptable quality class, and turbidity worsened post-monsoon due to stormwater-borne suspended solids. 4) DO and BOD? as primary degradation drivers: Low dissolved oxygen and high biochemical oxygen demand — direct consequences of untreated sewage — were the dominant contributors to elevated WQI, particularly at Budh Vihar (DO 2.2 mg/L; BOD? 14.8 mg/L pre-monsoon), contributing an estimated 55–65% of the total weighted score at downstream stations. Without systemic transformation — universal sewage treatment, ecological minimum flow maintenance, riparian habitat restoration, and robust real-time monitoring — the Yamuna faces progressive biological impoverishment and loss of its capacity to serve as a safe water source for Delhi\'s population exceeding 20 million.

References

[1] APHA (2017). Standard Methods for the Examination of Water and Wastewater, 23rd edn. American Public Health Association, Washington D.C. [2] BIS (2012). IS 10500: Indian Standard Drinking Water — Specification (2nd Revision). Bureau of Indian Standards, New Delhi. [3] Brown, R.M., McClelland, N.I., Deininger, R.A. & Tozer, R.G. (1970). A water quality index — do we dare? Water and Sewage Works, 117(10), 339–343. [4] CPCB (2021). Water Quality Monitoring in India — Annual Report. Central Pollution Control Board, Ministry of Environment, Forest & Climate Change, New Delhi. [5] Horton, R.K. (1965). An index number system for rating water quality. Journal of Water Pollution Control Federation, 37(3), 300–305. [6] Kaur, R. & Sharma, S. (2015). Assessment of water quality of Yamuna River in Delhi using WQI approach. International Journal of Engineering Research and Applications, 5(4), 50–56. [7] Khwakaram, A.I., Majid, S.N. & Hama, S.A. (2012). Determination of WQI for Qalyasan Stream, Kurdistan Region. International Journal of Plant, Animal and Environmental Sciences, 2(4), 148–157. [8] Meena, H., Singh, S. & Khan, M.A. (2019). Comparative analysis of NSF and CPCB WQI methods for Yamuna River. Indian Journal of Environmental Protection, 39(5), 412–418. [9] Sargaonkar, A. & Deshpande, V. (2003). Development of an overall index of pollution for surface water in Indian context. Environmental Monitoring and Assessment, 89, 43–67. [10] Sharma, D. & Kansal, A. (2011). Water quality analysis of River Yamuna using WQI in the national capital territory, India. Applied Water Science, 1(3–4), 147–157. [11] Tiwari, T.N. & Mishra, M.A. (1985). A preliminary assignment of water quality index of major Indian rivers. Indian Journal of Environmental Protection, 5(4), 276–279. [12] WHO (2017). Guidelines for Drinking-Water Quality, 4th edn. World Health Organization, Geneva. [13] Bhardwaj, R., Gupta, A. & Tiwari, J.K. (2017). Assessment of water quality using principal component analysis and regression analysis. Environmental Monitoring and Assessment, 189(3), 110–125. [14] Singh, V., Rai, S.P. & Bhatt, M.P. (2020). Spatio-temporal variation of heavy metals and associated health risk assessment in Yamuna River, Delhi. Environmental Science and Pollution Research, 27(8), 8334–8351. [15] Delhi Jal Board (2022). Annual Report on Sewage Treatment Capacity and Infrastructure, Government of National Capital Territory of Delhi, New Delhi. [16] Ramakrishnaiah, C.R., Sadashivaiah, C. & Ranganna, G. (2009). Assessment of water quality index for the groundwater in Tumkur Taluk, Karnataka State, India. E-Journal of Chemistry, 6(2), 523–530. [17] Tyagi, S., Sharma, B., Singh, P. & Dobhal, R. (2013). Water quality assessment in terms of water quality index. American Journal of Water Resources, 1(3), 34–38. [18] Chaturvedi, M.K. & Bassin, J.K. (2010). Assessing the water quality index of Wazirabad, Delhi. Applied Water Science, 1(1–2), 39–46. [19] Suthar, S., Sharma, J., Chabukdhara, M. & Nema, A.K. (2010). Water quality assessment of river Hindon at Ghaziabad, India: impact of industrial and urban wastewater. Environmental Monitoring and Assessment, 165(1–4), 103–112. [20] Akhtar, N., Syakir Ishak, M.I., Bhawani, S.A. & Umar, K. (2021). Various natural and anthropogenic factors responsible for water quality degradation: a review. Water, 13(19), 2660. [21] Mishra, A. & Tripathi, B.D. (2008). Seasonal and temporal variation in physicochemical and bacteriological characteristics of river Ganga in Varanasi. Environmental Monitoring and Assessment, 140(1–3), 243–254. [22] Patel, P., Raju, N.J., Reddy, B.C.S.R., Suresh, U., Gossel, W. & Wycisk, P. (2018). Geochemical processes and multivariate statistical analysis for the assessment of groundwater quality in the Sattankulam Aquifer, Tamil Nadu. Applied Geochemistry, 101, 55–70. [23] Kumar, R., Kumar, S., Pandey, R. & Trivedi, R.K. (2016). A review on water quality index: significance and methods. International Research Journal of Engineering and Technology, 3(11), 1054–1060. [24] Nemerow, N.L. & Sumitomo, H. (1970). Benefits of Water Quality Enhancement. Report No. 16110 DAJ, prepared for the US EPA, Syracuse University, Syracuse, NY. [25] Chabukdhara, M., Gupta, S.K. & Kotecha, A. (2017). Groundwater quality in Kala-Amb, Himachal Pradesh, India: spatial distribution and health risk assessment. Chemosphere, 179, 167–177. [26] Garg, S.K. (2018). Environmental Engineering, vol. II: Sewage Waste Disposal and Air Pollution Engineering. Khanna Publishers, Delhi, India. [27] Verma, R. & Dwivedi, P. (2013). Heavy metal water pollution — a case study. Recent Research in Science and Technology, 5(5), 98–99. [28] Bunting, L., Leavitt, P.R., Simpson, G.L., Wissel, B. & Cumming, B.F. (2016). Increased variability and sudden ecosystem state change in Lake Winnipeg. Limnology and Oceanography, 61(6), 2090–2107. [29] Shiklomanov, I.A. (1993). World fresh water resources. In: P.H. Gleick (ed.) Water in Crisis: A Guide to the World\'s Fresh Water Resources. Oxford University Press, New York, pp. 13–24. [30] Pesce, S.F. & Wunderlin, D.A. (2000). Use of water quality indices to verify the impact of Cordoba city (Argentina) on Suquia River. Water Research, 34(11), 2915–2926. [31] Abbasi, T. & Abbasi, S.A. (2012). Water Quality Indices. Elsevier, Amsterdam, The Netherlands. [32] Giri, S. & Singh, A.K. (2014). Assessment of surface water quality using heavy metal pollution index in Subarnarekha River, India. Water Quality, Exposure and Health, 5(4), 173–182.

Copyright

Copyright © 2026 Amrita Kashyap, D.C. Rahi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.