Introduction

The Yamuna is a tributary of the holy Ganges. The main stream of the Yamuna River originates from the Yamunotri Glacier at Bandar Panch (38°59'N, 78°27'E) in the Mussoorie Ranges of the lower Himalayas, at an average altitude of about 6387 meters above sea level in the Uttarkashi district (Uttrakhand) increase. The Yamuna basin includes the states of Uttarakhand, Uttar Pradesh, Himachal Pradesh, Haryana, Rajasthan, parts of Madhya Pradesh and Delhi.  The Yamuna is a sub-basin of the Ganges river system. Area of Ganges basin is 861,404 km². Yamuna and its basin together contribute a total of 345,848 km² or 40.14 per cent of the total Ganges basin (CPCB, 1982- 83). It is important to protect its water quality since a large population depends on the river Yamuna. 

The river is polluted from both point and nonpoint sources, with the National Capital Territory (NCT). Delhi is the main contributor of pollutants, followed by Agra and Mathura. About 85 percent of total pollution originates from Delhi sever water. 

The Yamuna flows 1,370 km through the plains of Uttar Pradesh to its confluence with the Ganges at Allahabad. The major tributaries of the Yamuna River are Thong, Betwa, Chambal, Ken and Sind. The Yamuna basin covers 40.14 per cent of the Ganga basin and 10.7 per cent of the country in terms of area. Water in Yamuna was described as having a light blue color in the early 20th century. However, due to its high population density and rapid industrialisation, the Yamuna in Delhi is currently one of the most polluted rivers in the world especially the capital city of India. 2 per cent of the river's length passes through Delhi between Wazirabad and Okhla, but the city contributes about 76 percent of the river's total pollution. Sewage and industrial wastewater are discharged into the sewer system of Delhi. The National Green Court has issued a series of guidelines and imposed environmental compensation on departments and agencies that fail to provide appropriate industrial wastewater and wastewater treatment plants prior to discharge, treated into sewers and water bodies. A large portion of Delhi residents live in settlements with no planning, no sewage system, or even in places where sewage systems refuse to connect. Many domestic industries are prohibited from carrying out industrial activities that discharge wastewater into the sewer system. In addition, tons of construction wastes were dumped into sewers and rivers that the authorities responsible for monitoring did not take any coercive measures.

The water quality of the Yamuna River has deteriorated severely over the years. The physical, chemical and biological components determine water quality (Allee and Johnson, 1999). Substances such as heavy metals, pesticides, detergents and petroleum form the chemical composition (Tiwari et al., 2020). Turbidity, color, and temperature make up the material composition, while biological arrangements include pigments and plankton.

Within the ambit of this research, using secondary data, how the exponential rise in the population is contributing to the increase in the overall demand, which is the primary contributing factor behind the rise in industrialisation and urbanisation that ultimately increases pollutant discharge in the water causing severe pollution. This will further analyze the level of various contributing pollutants via analysing the physicochemical characteristics of the water in River Yamuna and its impacts, which is the ultimate reason behind the categorisation of Yamuna as dying or ailing river. 

Review of Literature

There are scholarly research works on the condition of deterioration of water resources available as well as there are also works that the deteriorating condition of River Yamuna in Delhi. The researchers have also analyzed the physicochemical characteristics have discussed the various issues that has been caused due to the effluent discharge and rapid unplanned urbanisation. Increased water demand, and poor sewage treatment plants is seriously affecting water resources and change the environment and ecosystems. 38 per cent of municipal wastewater is treated (CPCB, 2015) in India and 80 per cent of the freshwater sources are polluted (Dey 2015). Water quality along the entire Yamuna River basin has been analyzed by the Central Water Commission (CWC) and the Central Pollution Control Commission in the recent years. The investigation revealed six distinct sections of the river characterized by flow characteristics, pollution sources, and water quality. 

These are the Himalayas to Tajewala, the upper reaches from Tajewala to Wazirabad, the Delhi sector between Wazirabad and Okhla, the Delhi-Agra sector, and the confluence of Agra and Agra. Bio-agglomeration and high bacterial activity reduce turbidity in summer in Delhi (Bhargava, 1985a).  85 per cent of river pollution comes from domestic sources (CWC, 2009). The main sources of pollution are pollution from untreated sewage, industrial wastewater, garbage, corpse dumping, and water use in streams (CPCB, 2006). 

In addition, heavy withdrawals reduce the diluting capacity of rivers, further contamination. Delhi, the country's capital, is the leading source of pollution in the Yamuna River. Sewage Treatment Plants (STPs) have been built in various urban centers to maintain river water quality. Treated, untreated or partially treated effluents from these sewage treatment plants are discharged into rivers either directly or via carrier discharge (CSE India, 2007). This poses a major threat to water quality into rivers at some points without treatment (CPCB, 2006).

While reviewing information from the mentioned scientific works and the related data, this research paper highlights the most prominent and the most discussed issues of water pollution. The research primarily aims to highlight the level of various contributing pollutants, the physicochemical characteristics of the water in River Yamuna and its impacts, which is the ultimate reason behind the categorization of Yamuna as Dying or ailing river. 

Research Area

The Yamuna River flows into the National Capital Region (NCT). Prior to entering the NCT at Palla, the Yamuna River passed 393 km at its source and approximately 220 km at Hathnikund Dam. 

According to Haryana State Pollution Control Board (HSPCB), the numbers of industries in Yamunanagar, Kernal, Panipat, and Sonipat are 142, 9, 346, and 503, generating effluent of 16,420.90, 26.00, 65,696.97, and 15,668.50 KLD, respectively (August 2019). Several drains of Haryana state including 3 major drains at Dhanaura escape, Main Drain No.2, and Drain No. 8 also fallout in river Yamuna before reaching Palla. (Joshi.et.al, 2022). 

Objectives

Using the secondary data available, this study focuses on the following objectives: 

1) To study the physicochemical characteristics of River Yamuna.

2) To study the impacts on water quality of River Yamuna in Delhi.

Research Methodology

This paper tries to examine the various physicochemical parameters of surface water of the Yamuna River by quantitatively and qualitatively analysing the secondary data obtained from the Bureau of Indian Standards, the CPCB Annual Report and from the Delhi Pollution Control Committee. The descriptive analysis was done by taking the averages to find the trend of the levels of parameters present in water for the effective and efficient achievement of the object.

Results and Discussion

Permissible limit of physicochemical parameters of surface water

Table 1: Showing the permissible limit of physicochemical parameters of surface water (Bureau of Indian Standards)

Table 2: Water Quality of Yamuna River in Delhi { mg/l}

Contamination of PH in River Yamuna in Delhi

Water pH level is used to measure the acidity and alkalinity of water. It ranges from 0 to 14, with 7 meaning neutral. A pH less than 7 indicates how acidic the water is, and a pH greater than 7 indicates how alkaline the water is. 

The comparative analysis of water quality parameters, specifically pH levels, between 2011 and 2022 at different locations along the Yamuna River, raises significant concerns about environmental degradation. In Palla, there was a substantial decrease in pH from 8.6 in 2011 to 7.23 in 2022, indicating a noteworthy shift towards acidity. Wazirabad Barrage witnessed a slight decrease in pH from 7.96 (2011) to 7.41 (2022), while Kudesia Ghat experienced a substantial drop from 7.69 to 6.92 during the same period. ITO Bridge showed a decrease from 7.59 to 7.11, and Nizamuddin Bridge exhibited a decline from 7.68 to 7.24, both within the acceptable range but signalling a shift towards acidity. Agra Canal (Okhla) and Downstream Okhla Barrage also demonstrated decreasing pH values, from 7.75 to 7.3 and 7.74 to 7.33, respectively. The overall trend indicates a decline in pH levels across the locations, underscoring the need for immediate attention, continuous monitoring, and comprehensive measures to identify and address potential pollution sources. The observed changes raise concerns about the deteriorating water quality in these regions and emphasize the urgency of implementing sustainable management practices to mitigate further environmental impact.

Contamination of Chemical Oxygen Demand (COD) in Yamuna River

COD is defined as the approximate amount of oxygen required by organic matter in the wastewater to be finally oxidized, and also defined as the amount of oxygen consumed by organic matter. 

The comparative analysis of COD levels in the Yamuna River at various locations in 2011 and 2022 reveals concerning trends. In Palla, COD has increased from 19.5 mg/L in 2011 to 37 mg/L in 2022. Wazirabad Barrage shows a substantial rise from 37 mg/L to 72 mg/L during the same period. Kudesia Ghat has witnessed a significant increase from 90 mg/L to 192 mg/L. ITO Bridge and Nizamudin Bridge also experienced an increase in COD levels, with values reaching 160 mg/L and 176 mg/L, respectively. Agra Canal at Okhla and Downstream Okhla Barrage show a rise from 91.64 mg/L to 168 mg/L and from 73.09 mg/L to 208 mg/L, respectively. These alarming increases in COD levels pose a severe threat to the Yamuna River, indicating elevated chemical pollution that could lead to the degradation of water quality and harm aquatic ecosystems. The rise in COD levels over the years suggests an increase in organic and inorganic pollutants, possibly originating from industrial discharges, urban runoff, or untreated sewage. 

To address this escalating pollution, immediate measures are essential, including stricter regulations on industrial effluents, improved wastewater treatment facilities, and public awareness campaigns to promote responsible waste disposal. Collaborative efforts from authorities, industries, and the public are crucial to mitigate the threat posed by rising COD levels and safeguard the ecological health of the Yamuna River.

Contamination of Biochemical Oxygen Demand (BOD) in Yamuna River

Biochemical Oxygen Demand (BOD) is defined as the amount of dissolved oxygen used by microorganisms during the biochemical metabolism of organic matter in water. More BOD reflects more suspended organic matter and less available dissolved oxygen.

The water quality data for the Yamuna River at various locations in 2011 and 2022 reveals a concerning increase in Biochemical Oxygen Demand (BOD) levels. In 2011, BOD levels ranged from 2.5 mg/L to 70 mg/L, while in 2022, these values escalated to a range of 2.07 mg/L to 54.25 mg/L. Palla and Kudesia Ghat witnessed a decrease in BOD levels, but the majority of locations experienced a substantial increase, with Wazirabad Barrage, ITO Bridge, Nizamuddin Bridge, Agra Canal (Okhla), and Downstream Okhla Barrage demonstrating notable spikes. Elevated BOD levels indicate increased organic pollution, posing a significant threat to the Yamuna River ecosystem. The surge in BOD can deplete dissolved oxygen (DO) levels, negatively impacting aquatic life and overall water quality. The data underscores the alarming state of pollution in the Yamuna River, and urgent measures are required to mitigate this threat. Efforts should focus on enforcing and enhancing water treatment practices, implementing stricter regulations on industrial and domestic wastewater discharge, and promoting public awareness to foster a collective responsibility for the preservation of this vital water resource. Additionally, regular monitoring and the adoption of advanced water treatment technologies are imperative to curb the escalating pollution levels and ensure the sustainable health of the Yamuna River.

DO in Water Quality of Yamuna River in Delhi

Dissolved Oxygen (DO) is a measure of the amount of dissolved oxygen in water - the amount of oxygen available to living aquatic organisms. The data for different water quality parameters in the Yamuna River at various locations in 2011 and 2022 reveals significant changes, particularly in Dissolved Oxygen (DO). In Palla, DO decreased from 8.1 mg/L in 2011 to 7.61 mg/L in 2022. Wazirabad Barrage witnessed a substantial drop in DO from 5 mg/L to NIL, indicating a severe decline in oxygen levels. Kudesia Ghat experienced a concerning decrease in DO from NIL in 2011 to 2.17 mg/L in 2022, highlighting potential threats to aquatic life. 

ITO Bridge showed a reduction in DO from 0.4 mg/L to 1.1 mg/L, indicating deteriorating water quality. Nizamuddin Bridge also experienced a decline in DO from NIL to 2.77 mg/L. Agra Canal (Okhla) showed a decrease from NIL to 1.87 mg/L, while Downstream Okhla Barrage witnessed a substantial drop in DO from NIL to 1.9 mg/L. The declining DO levels across locations signify a serious threat to the Yamuna River ecosystem, jeopardising the survival of aquatic organisms. 

Such decreases in DO are indicative of increased pollution, likely due to higher levels of organic and chemical pollutants. Immediate measures are crucial to curb pollution sources, enhance wastewater treatment, and enforce strict regulations to ensure the restoration of DO levels in the Yamuna River. This includes implementing effective sewage treatment practices, reducing industrial discharges, and raising awareness about responsible waste disposal practices among communities along the river. Only through concerted efforts can the health of the Yamuna River be safeguarded for both the ecosystem and the communities dependent on it.

Conclusion

The comprehensive analysis of water quality parameters in the Yamuna River spanning multiple years, focusing on key indicators such as pH, COD, BOD, and Dissolved Oxygen (DO), paints a vivid picture of the escalating environmental challenges faced by this vital water resource. Examining the pH levels reveals an alarming trend, with numerous locations experiencing a decline between 2011 and 2022. Palla, for instance, saw a substantial decrease from 8.6 to 7.23, signaling a shift towards acidity. Similar trends were observed in other locations, including Kudesia Ghat, ITO Bridge, Nizamuddin Bridge, Agra Canal (Okhla), and Downstream Okhla Barrage. These changes, although within acceptable limits, underscore a potential deterioration in water quality, necessitating continuous monitoring and immediate intervention.

The analysis of COD levels reveals a disturbing increase across all locations between 2011 and 2022. Wazirabad Barrage, Kudesia Ghat, ITO Bridge, Nizamuddin Bridge, Agra Canal (Okhla), and Downstream Okhla Barrage experienced significant spikes in COD, indicating heightened chemical pollution. Such a surge in COD levels poses a severe threat to the river ecosystem, potentially stemming from industrial discharges, urban runoff, or untreated sewage. Addressing this challenge requires stringent regulations, improved wastewater treatment facilities, and public awareness campaigns to encourage responsible waste disposal practices.

Furthermore, the examination of BOD levels exposes a concerning rise in organic pollution. While Palla and Kudesia Ghat exhibited a decrease in BOD, locations such as Wazirabad Barrage, ITO Bridge, Nizamuddin Bridge, Agra Canal (Okhla), and Downstream Okhla Barrage witnessed substantial increases. Elevated BOD levels pose a direct risk to aquatic life by depleting dissolved oxygen, further underscoring the urgent need for comprehensive pollution control measures. The most critical revelation comes from the analysis of Dissolved Oxygen levels, which indicates a pervasive threat to the river's health. 

Across various locations, there was a consistent decline in DO levels between 2011 and 2022. Wazirabad Barrage, Kudesia Ghat, ITO Bridge, Nizamuddin Bridge, Agra Canal (Okhla), and Downstream Okhla Barrage all experienced a significant drop in DO. This decline jeopardises the survival of aquatic organisms, indicating the severe impact of pollution on the river's ecosystem.

In conclusion, the collective analysis underscores the urgent need for immediate and sustained measures to address the escalating pollution levels in the Yamuna River. The observed trends in pH, COD, BOD, and DO levels point to an environmental crisis that demands a holistic approach, including the enforcement of stringent regulations, improved wastewater treatment infrastructure, and community engagement in responsible environmental practices. The preservation of the Yamuna River requires a collaborative effort involving government bodies, industries, and the public to ensure a sustainable and healthy future for this vital water resource. Only through concerted action can the adverse trends in water quality be reversed, and the ecological balance of the Yamuna River be restored for generations to come.

India's struggle to address the escalating pollution in the Yamuna River underscores policy failures and limitations in tackling this complex environmental challenge. Several policies, including the National Water Policy (2012), National Mission for Clean Ganga (Namami Gange), and the Yamuna Action Plan (YAP) with its Phase II (YAP-II), have been implemented to rejuvenate river ecosystems and control pollution. However, the broad scope of these policies often lacks specificity and struggles with effective implementation. Despite the significant role played by the National Green Tribunal (NGT) in issuing directives to curb pollution, execution challenges and difficulties in ensuring compliance have hindered their impact. Investments in Sewage Treatment Plants (STPs) and Effluent Treatment Plants (ETPs) aimed at treating wastewater have been marred by operational issues and inadequate capacities, resulting in continued pollution. Industrial pollution control measures, governed by acts like the Water and Air (Prevention and Control of Pollution) Acts, face shortcomings in enforcement and penalties, allowing industries to discharge pollutants with limited consequences. 

The overarching focus on Namami Gange sometimes overshadows the specific needs of the Yamuna, and overall, there is a lack of stringent measures to curb pollution sources and promote sustainable water management. The failure to adequately address the root causes of pollution, including urbanisation and industrialisation, further underscores the need for a more integrated, targeted, and proactive approach. Comprehensive measures, including stringent enforcement, enhanced infrastructure, sustained public involvement, and a more nuanced consideration of the Yamuna's unique challenges, are imperative to effectively tackle the pollution crisis and ensure the long-term sustainability of this vital water resource in India.

Recommendations

1. Construction of new sewage treatment plants (STP), capacity expansion of existing sewage treatment plants, modernisation of technology.

2. On-site treatment of large volumes of wastewater.

3. Diversion of Industrial Waste: All industrial waste is diverted to a communal sewage treatment plant. Industries that don't send their waste to sewage plants will be cracked down.

4. Adequate sewer network: JJ clusters are connected to a larger sewer network to completely prevent contamination of storm drains. Each home can also be connected to the sewer network.

5. Desludging: complete desludging of the entire sewage network.

6. Encouraging community participation.

7. Implementation of Circular economic measures.

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