Introduction

The essentiality of freshwater availability cannot be denied, as it aids in the development of society, the economy, politics, and rivers, which are vital to the socioeconomic progress of every nation. However, river systems are extensively contaminated nowadays because of the growing danger to water quality—which is lowered by factors including urbanization, industry, development projects, and human density (Mansor et al. 2024; Akhtar et al. 2021). Pollution adversely affects freshwater quality, primarily due to industrial and agricultural activities (Hothi et al. 2022; Koop and Leeuwen 2017). Figure 1 illustrates several causes of water pollution, such as construction, runoff from farmland, and urban and industrial effluents. This shows how several factors that affect water quality are intricately connected. River water's qualitative and quantitative attributes are significantly impacted by variations in surface water runoff, precipitation, groundwater flow, and human water usage throughout the year (Pattnayak et al. 2023; Kluska and Jabłońska 2024).

Fig. 1
figure 1

Sources of water pollution (Anderson et al. 2019)

Full size image

Since the Himalayan rivers are essential to life and greatly influence traditions like mass bathing on festivals, they are essential to Indian culture (Haberman 2023). Three principal rivers emerge from the Himalayan highlands: Yamuna, Ganga, and Brahmaputra. These rivers are utilized for transportation, irrigation, fishing, hydroelectric power production, and cultural purposes. This comprehensive study concentrates on the Yamuna River, which is located at Yamunotri and runs through the states of Madhya Pradesh (MP), Himachal Pradesh (HP), Haryana, Delhi, and Rajasthan.

The need for clean drinking water is growing daily and is a global issue. In the meantime, the two main sources of the problem are the declining state of our environment and the growing concern over waterborne illness (Jaspal and Malviya 2020; Sharma et al. 2020a, b). Industrial areas are the prime area to be concerned about. Numerous contaminants have significantly altered the water quality in these areas, endangering the health of both humans and animals (Koop and Leeuwen 2017). The water quality of the Yamuna River continues to decline downstream into Haryana and Uttar Pradesh as a result of sewage and wastewater discharge from large urban areas like Panipat (drain no. 2), Sonipat (drain no. 6), and Yamuna Nagar (ditch drain) (Rajan and Nandimandalam 2024).

The state of pollution in several river segments caused the decline in the river’s water quality because fresh water for drinking and irrigation has been eliminated, and the cumulative release of industrial, residential, and agricultural wastewater into the river has turned the stretch of the river into an open sewer (Kayastha 2024). The health of rivers is at even greater risk due to extreme climate-related events such as record-breaking heat waves and altered precipitation patterns (Pattnayak et al. 2023; Awasthi et al. 2022a, b; Yadav et al.2023). Addressing this requires a multifaceted approach to safeguard the water quality of the Yamuna and potentially prevent the spread of disease, which is crucial to assess the water's quality and locate the sources of pollution, such as agricultural runoff, industrial effluents, untreated sewage discharge, commercial and household wastewater, to halt the spread of illness (Muthaiyah 2020). Determining these sources and assessing the water quality is essential. This study focuses on the Yamuna River since it is one of India's most polluted rivers, which is unsafe to drink or take a bath. Even the contaminated fruits, vegetables, and other foods cultivated in its basin pose a health risk because of the contaminated water. But it seems logical to assume that pollution has become a concern. The problem, however remains challenging even after massive amounts of money have been spent on its solution.

This study is based on a critical review of the literature and primary data collected through different search engines such as Google Scholar and ScienceDirect from 2019 to 2023. The secondary data sources include the water quality data of River Yamuna in the year 2020 from the Central Pollution Control Board (CPCB). These sources were examined to identify the underlying water values driving the water management policies and plans in different stretches of the Yamuna River. This paper is divided into nine sections. Section "River Yamuna" comprehensively explores the different segments of the Yamuna River in India. Section "Sources of contamination in Yamuna River" discusses the sources of contamination in the water body such as industrial effluents, domestic wastewater, pollution from agriculture, biological contamination, and heavy metal pollution sources, and their impact on human health. Section "Water quality assessment" examines the state-wise studies of the River Yamuna, including Uttarakhand, Himachal Pradesh, Uttar Pradesh, Rajasthan, Haryana, Delhi, and Madhya Pradesh. Section "State-wise studies of River Yamuna" contains a discussion on the water quality concerning COVID-19. Section "Observations of water quality with respect to period of COVID-19" discusses the management and treatment of wastewater. The paper ends with concluding remarks and future perspectives. This review aims to gather information and studies on several contaminants that impact the quality of Yamuna water. Decision-makers will find the information useful in developing strategies to manage water pollution in the Yamuna.

River Yamuna

The Yamuna River, beginning at the Yamunotri glacier in Uttarakhand, serves as the lifeblood of the Himalayan region. Steeped in Hindu mythology and revered for its cultural significance, the Yamuna faces a growing threat like pollution, climate change, and floods, endangering its ecosystem and the well-being of those who rely on it. This critical waterway serves multiple purposes. Homes, industries, and farms all depend on its waters. Power plants, textile mills, paper mills, and chemical factories utilize it for production and cooling. Agriculture, the primary consumer of the Yamuna's water, irrigates vast tracts of land along the river's course. The vast majority of people living in the Himalayas rely exclusively on the river for water. Furthermore, millions in cities like Delhi, Mathura, Agra, and Allahabad quench their thirst and find sustenance thanks to this precious resource. The Yamuna's future health is critical for both the environment and the communities it sustains.

The Yamuna River is the principal tributary of the Ganga in the northern regions of India. It is sometimes referred to as the Jamuna or the Jumna. The percentage distribution of the major tributaries is shown in Fig. 2, with Hindon having the lowest proportion (2%) and Chambal having the largest percentage (40%) of all of them (Mishra et al. 2016). The catchment area of these tributaries is discussed in Table 1. It is a perennial river that receives its water from groundwater, precipitation, and snowmelt runoff (Joshi et al. 2023). One of the major natural sources of rivers is glaciers (Awasthi et al. 2022a, b). The Yamuna River originated from a glacier known as Yamunotri, which is located in the state of UK. At a height of 6387 m, this glacier is located on the western flanks of the Himalayan Banderpoonch peaks. Culturally and spiritually significant, the Yamuna River is home to many pilgrimage sites such as Yamunotri, Mathura, Paonta Sahib, Bateshwar, Vrindavan, and Allahabad. Numerous urban areas along its banks, including Yamunanagar, Sonipat, Gautam Budh Nagar, Delhi, Faridabad, Agra, and Mathura, further highlight its importance in daily life. Despite its cultural significance, the river faces challenges from human activities, impacting its fragile ecosystem (Arun et al. 2015).

Fig. 2
figure 2

Major tributaries of River Yamuna

Full size image
Table 1 State-wise total catchment area, percentage of contribution, drainage basin, percentage of drainage basin (Naithani and Pandel 2015; Upadhyay et al. 2013)
Full size table

Table 4 presents variations in the catchment regions of different Indian states, emphasizing the diverse contributions to the drainage basin (Naithani and Pandel 2015). UK and MP play crucial roles with larger catchment areas, while UP, though having a bigger catchment area, contributes relatively less. Smaller catchment regions of HP, Rajasthan, Haryana, and Delhi also make significant contributions to the drainage basin. This diversity underscores the complex dynamics of the Yamuna River and the need for comprehensive management strategies to address its challenges.

Segments of Yamuna River in India

The Yamuna River has been categorized into five distinct segments, namely the Upper, the Himalayan, Delhi, Diluted, and the Eutrophicated Segments which are based on its biological and hydrological characteristics (Sinha 2023). As the river flows through Haryana, specifically reaching Hathnikund/Tajewala, it passes through Ponta Sahib and is directed for irrigation into both the Western Yamuna Canal (WYC) and the Eastern Yamuna Canal (EYC) (Zehra et al. 2023). However, some sections between Tajewala and Delhi experience drying up during the dry season, primarily because there is no downstream water flow to the Tajewala barrage (Sharma and Gupta 2022). This situation changes as the river regains water through groundwater recharge and benefaction from a feeding channel via Som Nadi upstream of Kalanaur. After covering approximately 224 km, the river reaches Delhi near Palla village, where it is tapped once again at Wazirabad via barrage to provide drinking water to Delhi.

Proceeding downstream, there is a second barrage known as Okhla Barrage, located 22 kms after the Wazirabad barrage. The Okhla barrage directs river water towards the Agra Canal for irrigation (DAR 2023). Additionally, water from the Shahdara drain, originating from Noida, East Delhi, and Sahibabad, contributes to the river's flow past the Okhla Barrage (DAR 2023). The journey of the Yamuna concludes at Prayag (Allahabad), where it merges with the Ganga and an underground River Saraswati, receiving water from several significant tributaries (Sharma and Kansal 2011). Table 2 (Sharma and Gupta 2022; Mishra 2010; Sharma 2015) offers a comprehensive overview of the conditions and parameters influencing the quality of water in each section of the Yamuna River.

Table 2 Streams of the River Yamuna (Sharma and Gupta 2022; Mishra 2010; Sharma 2015)
Full size table

Sources of contamination in Yamuna River

The 2% of the entire catchment of river Yamuna flows via the National Capital Territory (NCT), Delhi and collects 79% of the river’s total pollution in a 48-km stretch resulting in the most polluted section of Yamuna River (Arora et al. 2023). The primary cause of pollution in the river, accounting for around 85%, is domestic sources. These include industrial effluents, raw manure, waste and dead body disposal, idol worship, and contaminants from water used in streams (Parihar et al. 2019).

According to available sources, surface water can be classified in 12 different ways, as illustrated in Fig. 3. The five major locations receiving water from these sources are listed in the centre column of Fig. 3. It is needed to understand the pollution sources to develop effective mitigation techniques. This discussion explores the various factors causing the deterioration of Yamuna's water quality. Each source contributes substantially to the deterioration of the river's health, including biological pollutants, heavy metals (HM), pollution from agriculture, untreated domestic wastewater, and industrial effluents released by industries. In the subsequent sections, each pollution source is discussed in detail, shedding light on the specific pollutants and their impact on the Yamuna's delicate ecosystem.

Fig. 3
figure 3

Categorization of water: sources, use, and possibility of contamination (Syeed et al. 2023)

Full size image

Industrial effluents

The River Yamuna is also described as the "River of grief " and "dirty river" in Delhi, Agra, and Mathura. This is mainly because of the seepage of untreated wastewater from the majority of Delhi's factories into the river, resulting in water that resembles an industrial sewer (Sarkar et al. 2017; Sarker et al. 2021). Most industrial complexes near riverbanks either do not treat or only partially treat effluents before discharging them into waterways (Tripathi et al. 2008; Syeed et al. 2023). River water is extensively utilized for industrial production, thermal power, and hydroelectricity generation (Syeed et al. 2023; Sarkar et al. 2019). The discharge of industrial wastes leads to elevated concentrations of HM contamination in the area (Yadav and Khandegar 2019).

In cities such as Faridabad, Mathura, Delhi, and Agra, numerous industrial facilities emit substantial quantities of untreated water into the Yamuna (Yadav and Yadav 2024). According to a report 359 industrial facilities dispose of their effluents indirectly or straight into the river. It has been reported that 42 industrial units in Delhi directly contribute to Yamuna contamination (Sharma 2021).

Domestic wastewater

Ninety per cent of the city's residential wastewater enters the Yamuna. It contains chemicals, phosphate compounds, laundry waste water, detergent, and other materials that cause harmful foam in the river (Vrat 2024). Usha and Singh (2024) reported a phosphate content of 0.51 mg/L which was higher than the standard range of 0.005–0.05 mg/L. The rivers were covered with toxic froth due to the excess phosphate concentration (Usha and Singh 2024).

Pollution from agriculture

Agricultural activities along the river's banks in Delhi contribute to pollution. Crops like radish, cabbage, cauliflower, tomatoes, and spinach are planted along the riverbanks. Runoff from agricultural farms during monsoon and non-monsoon rains, along with the discharge of irrigated water containing residues of insecticides, artificial fertilizer, pesticides, herbicides, and farmyard waste, directly or indirectly damages the river (Sharma et al. 2015). Agriculture is prevalent in the catchment areas and along the entire Yamuna Riverbank, leading to the drying up of river streams during the non-monsoon season and contributing to pesticide residue in the river (Mishra 2010).

Biological contamination

The Yamuna is significantly contaminated throughout its path through the NCT (Delhi), experiencing a conspicuous increase in Biochemical Oxygen Demand (BOD) and organic pollutants. BOD levels, crucial for measuring oxygen needed for microorganisms to break down organic substances, far exceed acceptable limits (Koop and Leeuwen 2017). The Yamuna’s total BOD level is approximately 93 mg/L, as compared to the CPCB requirement of 3 mg/L (Patel et al. 2020). In comparison to the World Health Organization (WHO) criterion of 5.0 mg/L, where they represent a hazard to aquatic life due to insufficient oxygen delivery, the obtained values were relatively low.

The Chemical Oxygen Demand (COD) measures both biodegradable and non-biodegradable compounds. Koop and Leeuwen (2017) found that the mean annual COD concentrations in the Yamuna River fluctuated from 202.66 mg/L in the summer to 64 mg/L during the monsoon, 89 mg/L in the winter, and 71.11 mg/L in the spring. These results are relatively low, which  aligns with the WHO guidelines limit of 250 mg/L. Lower BOD and COD levels indicate the existence of residential and commercial seepages as well as lower oxygen requirements, all of which point to a greater level of toxicity in the river water. The waterbody also consists of detergents which come under domestic waste (Sharma et al. 2014).

HM pollution sources

Naturally occurring elements are heavy metals. Due to the intricate interactions between human activities and natural processes, it is becoming more prevalent in the natural environment (Rajan and Janardhana Raju 2023). HMs released as a by-product of industrial activities pose a significant threat to water bodies, especially in heavy industrial zones (Syeed et al. 2023). The Yamuna experiences HM contamination, with metals like Cr, Cd, Zn, Cu, Ni, and Pb (Kr et al. 2018). It has been the main concern for science, health, and the environment over the effects of some of the enormously poisonous, detrimental to the environment, and human carcinogenic metals rising availability and/or emission (Okpara et al. 2022). Therefore, water's high content of HM has an impact on the water's quality (Vasistha and Ganguly 2020).

Metal ions are hazardous, risky, and destructive among other organic and inorganic water contaminants because of the way they naturally degrade tissue (Malik 2014). Some harmful HM, such as Chromium (Cr), Mercury (Hg), Cadmium (Cd), Silver (Ag), Lead (Pb), Barium (Ba), Arsenic (As) Thallium (Tl), and Selenium (Se), are included in the metallic compounds (Syeed et al. 2023). HM contamination is categorical by proving its existence in the water environment. Table 3 suggested that HMs may contaminate aquatic ecosystems, emphasizing the need for monitoring and controlling their presence to safeguard both human health and water quality. River water can include iron from geological sources, such as weathering and the breakdown of iron-rich minerals like magnetite, hematite, and illite, or household and industrial effluents coming from drains (Sarkar and Shekhar 2018). Also, due to mining, leaching from soils or riverbanks, geothermal springs, and anthropogenic sources, the concentration of As is higher in the surface waters globally (Rajan and Nandimandalam 2024). The breakdown of Mn-rich rocks, such as limestone, shale, and mafic rock, as well as human-generated contaminants such as sewage and untreated industrial effluent, are frequently linked to the occurrence of Mn in surface water (Hou et al. 2020).

Table 3 Presence of HM in diverse water conditions (Bhateria and Jain 2016; Kr et al. 2018)
Full size table

Significant levels of different heavy metals have been found in the Yamuna River's water, depending on the monitoring of the river's quality. The most prevalent element in the Yamuna water is Fe, even beyond the permissible limit. Various health problems, including inhibited growth and development, organ damage, cancer, impairment of the nervous system, etc., can result from such high concentrations of heavy metals in the water (Jaiswal et al. 2022).

According to (Sehgal et al. 2012), two areas between the Okhla and Wazirabad barrages that appeared to be hotspots for river water degradation were found to have greater concentrations of several HM. Yadav and Khandegar 2019 observed that the broad flow of industrial wastes into the Yamuna River was the cause of the fluctuating concentration of HM. The contamination of HM in the aquatic environment has grown to be a universal concern in recent years due to their invulnerability and the poisonous effects that the majority of them have on species. Ni, Cd, and Pb, three HM, are hardly ever found in considerable concentrations (Nielsen et al. 1999; Malik 2014).

Even at low concentrations, HMs are extremely poisonous and can have negative long-term consequences on the environment as well as human well-being. It can lead to various health issues, including cancer, organ damage, neurological diseases, and developmental anomalies. Large-scale industrial accidents or mining disasters, which involve the release of HM, can have devastating immediate effects that generate media attention and public protest. Therefore, the next section focuses on HM pollution, but it is essential to comprehend that other pollution sources, like industrial effluents, agricultural runoff, etc., also have a substantial effect on human health and water quality.

Impact of HM on human health

HMs are identified to have detrimental consequences on health and have been demonstrated to enter through water and food in the human figure (Malik et al. 2014). Certain HM species, including Ni, Fe, Zn, Mn, and Cu, are required by the human body and other organisms at minimal levels. However, when their maximum concentration limit (MCL) is exceeded, these metals pose a major risk to both the ecosystem and human well-being (Sankhla et al. 2016; Srivastava and Majumder 2008). Table 4 highlights the primary sources of these HMs, the MCL requirements for those metals in water, and the illnesses and symptoms that can result from exposure to those metals (Okpara et al. 2022; Fiyadh et al. 2023). It emphasizes the need to observe and control the quantity of these HMs in water to safeguard human health and address potential health concerns.

Table 4 HM and their effect on human health (Fiyadh et al. 2023; Okpara et al. 2022)
Full size table

Higher levels of Pb are associated with adult peripheral neuropathy and cognitive impairment in children (Kaur and Mehra 2012). Chronic lead exposure may have negative consequences on the vitamin D metabolism, blood, kidneys, blood pressure, and Central Nervous System (CNS) with severe exposure leading to kidney damage, brain damage, and gastrointestinal illness (Parihar et al. 2019). Cd exposure has been linked to persistent kidney tubular damage, an increased risk of gene mutations, decreased semen quality (De Angelis et al. 2017), visual motor impairment, and loss of concentration (Okpara et al. 2022). Ni is the metal most frequently causing concerning human health, and in higher quantities, it could result in cancer and respiratory issues (Mrozik et al. 2021). Symptoms of Zn intoxication include kidney and liver damage, vomiting, icterus, and diarrhoea (Nriagu 2007; Malik et al. 2014).

After discussing the enormous sources of contamination, the focus now shifts to a thorough investigation of the river Yamuna and its conditions in different states. The Yamuna River has distinct features and difficulties as it flows through several Indian states. The next sections will examine each of these segments in detail, providing an overview of the Yamuna River's current condition and the steps that must be taken to ensure its continued existence.

Water quality assessment

Water quality assessment is the process of evaluating the physical, chemical, and biological characteristics of water regarding its natural condition, human influences, and potential applications. Water quality is evaluated to see if it is safe for the environment or acceptable for consumption and other applications, including irrigation and sustenance of aquatic life. This is often done by comparing the physical, chemical, and biological characteristics of the water against a set of specifications (Adelagun et al. 2021). Several physicochemical parameters that are frequently evaluated in research on water quality include water temperature, pH, DO, TDS, turbidity, ammonia, nitrate, HMs, chloride etc. Table 5 gives an overview of the acceptable limits as per different standards.

Table 5 Physico-chemical parameters of some established standards (BIS 10500-2012); CCME (2001); WHO (2011)
Full size table

State-wise studies of River Yamuna

The river Yamuna plays a crucial role in supplying drinking water to various regions, including India's capital, Delhi, and neighbouring states such as UK, Haryana, and UP. Fig. 4 shows the map of the different states in which the Yamuna River flows. However, concerns have risen over the last few years because of the decline in the water quality of the river. The discharge of large volumes of moderately treated and untreated effluent into the Yamuna, particularly between Wazirabad and Okhla in Delhi's NCT, has been a significant contributor to this decline. Additionally, the pollution is exacerbated by the waste generated by cities located along the river's bank. Various pollution sources ranging from large factories and urban slums to extensive colonies, affects the health of individuals living in rural areas who consume untreated water from Yamuna River. This collective impact has also caused substantial deprivation of the river’s water quality (Sharma and Chaudhry 2015). The Yamuna water diversion, detailed in Table 6 based on information from CPCB in 2000, illustrates the specific locations and constructions where water diversion occurs along the EYC and WYC (CPCB 2000). Table 6 outlines the intended use of diverted water and its subsequent effects on the river’s condition downstream. This information provides a concise yet comprehensive overview of the initiatives taken for water management and their effects on the Yamuna River across various states and areas. The barrages, while serving specific purposes, have also created a lotic (flowing) habitat by impeding the river's natural flow (Mishra 2010). Understanding the intricacies of water management and its consequences is essential for addressing the challenges faced by the Yamuna and ensuring sustainable water quality in the region.

Fig. 4
figure 4

Map showing the geographical distribution of Yamuna River in India source accessed from MapChart and QGIS software

Full size image
Table 6 EYC and WYC water diversion (CPCB 2000)
Full size table

Figure 5 shows that according to CPCB (2006), MP has the maximum catchment of river Yamuna while HP has the minimum.

Fig. 5
figure 5

Percentage state wise catchment of river Yamuna (CPCB 2006)

Full size image

This section explains a broader perspective of the Yamuna flowing through several states of India. The water quality of the Yamuna River is degrading due to untreated effluent discharge from various sources. The Yamuna Water Diversion, as outlined by the CPCB, emphasizes the need for nuanced water management to ensure sustainable quality.

In the next section a detailed study of individual states i.e. UK, UP, HP, Haryana, Rajasthan, MP, and Delhi will be discussed, understanding the flow of Yamuna through these states. The reason for effluent discharge will be discussed individually for the flowing states.

Uttarakhand

The UK, renowned for its Char Dham pilgrimage sites, including Yamunotri, Gangotri, Kedarnath, and Badrinath, holds significant importance in the confluence of vital river networks (Matta et al. 2012). These locations frequently face environmental challenges exacerbated by increasing water demand, inadequate sewage infrastructure, and a scarcity of wastewater treatment facilities. Yamunotri, positioned near the Yamuna River’s mouth, is a site of continuous bathing activities, contributing to the strain on water resources (Semwal and Akolkar 2006). Despite the ecological significance of the upper section of the Yamuna River in the Himalayas, characterized by healthy conditions and minimal sewage discharge, challenges persist due to rising water demand and insufficient wastewater management infrastructure (UePPCB 2022).

A study by Khanna et al. (2010) on the river Yamuna focussed on examining a range of various Physico-chemical parameters along a 20 km stretch of the Yamuna River, from Kalsi to Dakpatthar, during different seasons. According to the  study, of all the different seasons, the monsoon saw the highest level of Total Suspended Solids (TSS), Total Solids (TS), and Total Dissolved Solids (TDS) as well as the temperatures. Furthermore, winter observed the highest temperature and DO. The overall physicochemical parameters were found to be good, but seasonality greatly affected hydrological parameters. An important Yamuna tributary that runs through the UK's Garhwal region, the Tons River is essential to the dynamics of the river. The Tons River water quality in Dehradun, UK, was evaluated by Khanna et al. (2010), who discovered that seasonal variations were seen in pH, temperature, DO, and velocity. Their study also revealed that the primary sources of pollutants in the river were household garbage, agricultural runoff, and industrial discharge. The summertime increased BOD measurements indicated the possibility for bacteria to cause health risks (Khanna et al. 2010). Therefore, Sharma et al. (2015) concluded that industrial post-processing, agricultural residues, and environmental influences are the essential sources of pollution After they analysed the water quality indices of the UK’s Yamuna River. Moreover, the principal component analysis proved useful and required in creating relationships linking pollution to the present degree of quality When it comes to tackling big problems, we need to be laser-focussed with our actions. Just take a look at the research on how we humans are interconnected with the delicate ecology of UK’s water bodies which is clear that we need sustainable systems to keep our environment safe. From studying the water quality indicators of the Yamuna River in the UK, it was found that the main culprits of pollution were industrial waste, agricultural runoff, and domestic sources. By using Principal Component Analysis (PCA), we were able to draw connections between these pollution sources and the state of our water quality. This highlighted the need for us to take targeted steps to address these issues. The human activities correlate with the poor health of the river ecosystem in the UK just goes to show how crucial it is for us to use sustainable management strategies to protect our local environment.

Himachal Pradesh

The Tons River, which is the Yamuna’s biggest tributary, serves as a natural boundary line between the states of UK and HP. (Pandey et al. 2018). Even though it’s such a significant part of the landscape, there hasn’t been a lot of research done on this particular stretch of the river. Few studies that have been conducted didn’t find many problems with the water quality as it stands today.

The pollution issue in HP is getting out of control, especially with all the untreated industrial and household waste being dumped into the Yamuna near Ponta Sahib. It’s a harsh situation (Kashyap et al. 2016). In one significant study, Kasyhyap et al. (2016) thoroughly examined physicochemical water quality indicators throughout an 18 km stretch of the Yamuna in the pre- and post-monsoon seasons of 2014 (Kashyap et al. 2016). The study found clear seasonal fluctuations in eight sample areas chosen based on industrial wastewater discharge sites. The post-monsoon season observed the peak of turbidity, but the pre-monsoon witnessed the greatest levels of electrical conductivity (EC), pH, TDS, COD, BOD, Zn, and Fe. Elevated BOD and COD values exceeding permissible drinking water limits indicated significant pollution, attributing the rise to untreated household waste, industrial effluents, and urban runoff from the industrial core. Despite the pollution, the river segment was classified as Class "D," suitable for irrigation, regulated wastewater disposal, wildlife fisheries reproduction, and industrial cooling.

Another study focussed on the Sirmour region of HP, collecting 96 samples of surface water from eight sites along the river Yamuna between 2014 and 2015. The investigation aimed to assess water quality concerning nine HM and three non-metals. Results indicated contributors from both natural as well as anthropogenic activities to the abundance of metals in the river. In 2014 and 2015, identified aspects were held accountable for the degradation of river water quality. There was a noticeably high pollution load in the river lengths throughout 2015, as evidenced by the findings that the metals Cr, As, and Zn were extremely, moderately, and marginally polluting, respectively. Although the study did not show a direct threat to public health, it did highlight the need to halt some downstream operations to restore the region's water quality. The results highlight how closely environmental factors and human activities are connected. It just goes to show how important it is for us to take sustainable steps to protect HP’s precious water resources (Kashyap et al. 2015).

Uttar Pradesh

The Yamuna River, flowing through Agra in U.P., is like a lifeline. It’s a vital source of freshwater that furnishes the needs of industries, farms, and households. It’s not just a river, it’s a provider for the people (Pal et al. 2017). The Yamuna River’s watershed is like a complex web, and many drains are crisscrossing the bustling city of Agra (Naushad et al. 2014; Chadetrik et al. 2015). Mathura faces the same problem, with the Yamuna being the main source of fresh water. But the water quality is a big concern because of the densely populated watershed that’s all tangled up with numerous drains (Mayank and Tyagi 2013; Pal et. al 2017). The Fort Drain is a major participant when it comes to polluting the river. It’s famous for dumping heavy metals into the Yamuna (Biswas et al. 2018). The main factor contributing to the declining water quality in Agra and Mathura is the wastewater from Delhi, transported downstream, which is both untreated or inadequately treated. A study conducted by Issac and Siddiqui (2022), was a thorough, year-long study examining the water quality of nine sources in UP and Agra. Their research dug into the nitty-gritty, measuring 14 different water quality indicators. Apart from a few minor malfunctions like high hardness, TDS, and Sulphate levels during certain times of the year, the water quality was mostly aligned with the standards set by the WHO and the Bureau of Indian Standards. The WQI results indicated seasonal variations in the river water and were safe for drinking during the monsoon, but due to dilution, it was deemed unsafe for consumption in the monsoon, summer, winter or spring. Through PCA, it was possible to pinpoint key elements that significantly influence water quality and elaborate correlations between various quality data.

To identify the variables affecting the primary and secondary irrigation water quality, (Reddy et al. 2021) evaluated 24 water samples in the Chaka block of the Prayagraj district. Their research uncovered that the pH levels were ranging between 6.22 and 7.34, with the average hanging around 6.74. But when it came to the WQI for irrigation, all the samples were in poor condition. The study put the spotlight on the need for extra steps to improve the quality of irrigation water in the area. (Sharma et al. 2022) used satellite Imagine using Landsat satellite images, to look back over a decade (2009–2019) and study the Yamuna River near Balua Ghat, Allahabad. His finding was a bit concerning. Urban areas are consuming the open spaces along the river. After checking out factors like COD, temperature, BOD, and pH, it was clear that the unplanned growth of slums and reckless dumping of waste into the water were affecting the water quality. These findings are of utmost importance, especially as UP strives to meet the growing demands on the Yamuna.

Rajasthan

The Chambal River is a mighty stretch of water that’s 960 km long. It starts its journey in Indore, in the state of Madhya Pradesh (MP), and flows its way through Rajasthan, playing a huge part in the region’s water body(Sisodiya and Mathur 2021). Acting as a natural border between Rajasthan and MP, it finally meets the Yamuna in U.P. (Kumar et al. 2014). At Pachnada in Bhareh, a place that sits on the border of the UP districts of Etawah and Bhind. The Kwari, Chambal, Yamuna, Pahuj, and Sind rivers all come together in a grand confluence that occurred here (Chouhan et al. 2019).

Abba et al. (2015) conducted a thorough assessment of Chambal River’s water quality, using six different criteria. They found that the water quality ranged from ‘Fair’ to ‘Poor’. The water quality of Udi station was rated as ‘Marginal to Poor’ on the Canadian Council of Ministers of the Environment’s grading system, which uses a scale from 0 to 45. They zeroed in on instances from 2000 onwards where the water quality just wasn’t cutting it for drinking water standards. The WQI, which uses a scale from 0 to 32, was stamped as ‘Poor’ during 1999 and 2001–2003 because it didn’t meet the cutoff for drinking water standards. The water quality at the station took a spin between 2000 and 2004, often falling way short of what’s needed for drinking water.

According to a study published in 2019 by Chouhan et al. (2019), they routinely collected water samples from various locations along the Chambal River, primarily in Kota City. Their investigation revealed concerning trends in several water quality indicators during the pre-monsoon season. Parameters such as COD, EC, TDS, pH, BOD, and DO exhibit signs of depletion and contamination. Remarkably, the surface water quality of the Chambal River was suboptimal during that specific period. Given that the Chambal flows through Rajasthan, these studies underscore the urgent need for coordinated efforts to monitor and mitigate the impacts on this vital river ecosystem.

Haryana

The Yamuna River plays a crucial role in Haryana, flowing through Yamuna Nagar before it reaches Hatnikund. At this point, water is directed into Delhi's drinking water supply and irrigation system via the Western Yamuna Canal (WYC) and Eastern Yamuna Canal. Yamuna Nagar, the second-largest industrial city in Haryana, faces challenges due to high waste generation attributed to population growth, uncontrolled urbanization, and industrial expansion. The river's catchment area up to the Hatnikund headworks spans nearly 12,950 km2, and during the lean season, inadequate water flow downstream of the Hatnikund barrage leads to the river drying up in various stretches Rai et al. (2012).

Examining the physicochemical features of WYC water at three sampling points, Bhatnagar et al. (2009) found elevated pollutant levels downstream from the influx of sewage and industrial effluents. Parameters such as conductivity, turbidity, alkalinity, free CO2, hardness, calcium, chloride, magnesium, phosphate, orthophosphate, ammonia, and sulphate registered high levels, while DO showed lower values (DO) (Bhatnagar et al. 2009). DO and BOD emerged as crucial indicators of water quality. The WQI indicated significant pollution at the upper segments of the river, especially before the entry of residential and industrial pollutants. The middle stretch, where a drain carrying domestic waste and industrial effluent joins the river, and 6 km downstream from the point of entry of contaminants, exhibited severe pollution, particularly pronounced during the summer months.

Ravindra et al. (2003) contributed insights into the typical measures of water quality features at various Yamuna canal station locations. Notably, DO, exhibited higher values in winter compared to lower values in summer. Flow variations were evident between monsoon and non-monsoon seasons, with station 1 experiencing larger flows during the monsoon. Changes in water flow were observed in parameters like free CO2, hardness, alkalinity, and ammonia, decreasing in June and increasing in July, emphasizing the dynamic nature of water quality in the Yamuna River in Haryana (Ravindra et al. 2003). These studies collectively underscore the complex environmental issues faced by the Yamuna as it courses through Haryana, calling for comprehensive strategies to address pollution and sustain the river's health.

Delhi

The Yamuna River, which flows about 855 miles (1376 km) south from the Himalayas through several states, including Delhi, has been significantly affected by pollution. The toxic foam, a mixture of sewage and industrial waste, has formed over sections of the Yamuna River, leading to respiratory and skin problems (Arora and Mehra 2003). Despite its toxicity, many villagers downstream continue to use the water for bathing and even drinking. The river's pollution load is particularly high in areas surrounding Delhi, where the dense population and waste contribute significantly to the contamination (Sehgal et al. 2012). The Yamuna River, which is vital to Delhi but has severe pollution issues because of industrial emissions and urbanization, provides more than 70% of the city's water (Parween et al. 2017). Many drains that discharge significant volumes of pollutants into the river, such as the Shahdara and Najafgarh drains, raise the river's pollution levels (Bhardwaj et al. 2017). Despite its small size, the watershed region has substantial challenges with development and pollution. The Yamuna's pollution load is increased by the heavily industrialized districts' frequent waste releases, particularly during the dry seasons (Verma et al. 2022).

Research conducted by Madan et al. (2018) focussed on the Yamuna River in Delhi and the WQI of an industrial outlet. In their research, specifically studied the Yamuna River in Delhi and assessed the WQI of an industrial outlet. Their findings point to the Nizamuddin outflow point, the DO level was alarmingly low, registering 0% DO. This indicates extreme pollution in that section of the river and the gas turbine station and thermal power plant outputs also exhibited significant WQI values. These findings underscore the severe pollution in these industrial areas. Another study by (Nehra and Singh 2020), in their research, specifically studied the Yamuna River in Delhi with a particular focus on the Najafgarh drain. He claims that the Yamuna in Delhi has essentially transformed into a sewer. Without proper treatment, it is unusable due to severe contamination and The Najafgarh Drain carries significant volumes of organic waste and a high BOD load. This pollution could potentially pose a hazard to both the food chain and human health

Kaur et al. (2021) used ciliate populations as bio-indicators to evaluate how the Yamuna River's water quality affected the microbiological life. The Yamuna River's ciliates have been proven to be reliable bioindicators of pollution, and the study found that the river's quality significantly declined as it passed through Delhi NCR (Kaur et al. 2021 Table 7 of (CPCB (2021) Annexure VI (a)) shows that Delhi's water quality, like that of other states including Haryana and UP, struggles to meet the standards required for bathing. These findings underscore the pressing need for all-encompassing actions to mitigate pollution issues and protect the health of Delhi's Yamuna.

Table 7 Water quality data of River Yamuna (CPCB 2020) (CPCB 2021 annexure VI (a))
Full size table

Madhya Pradesh

MP also makes the vast network of the Yamuna River even richer, while the river’s tributaries present the essential signs of the general health of the system. The most prominent tributaries are underlined below. The Betwa River implies the main stream of the Betwa River Basin. A scholarly analysis of the periodic fluctuation of the physicochemical properties of the Betwa River was carried out by (Vishwakarma et al. 2013) between October 2011 and Aug 2012. Substantially, high COD, BOD, and hardness were noticed in Nayapura and Mandideep, which can be interpreted as evidence of pollution in these sites. The present quality of the river of Betwa was characterized by low pH and DO in Vidisha, Bhojpur, and Jhirri, demonstrating the dynamics of the river’s water quality.

The physicochemical properties of the Ken River, another Yamuna tributary in MP, were studied by Awasthi et al. (2018). Numerous data were analysed at seven monitoring sites in and around the Panna District, including pH, temperature, EC, turbidity, TDS, TSS, DO, COD, BOD, chloride, phosphate, sulphate, nitrate, alkalinity, total hardness, calcium and magnesium hardness. The conditions were very alkaline, as shown by the pH values, which varied from 7.21 to 7.22. Average conductivity varied seasonally from 600 to 1100 μmhos/cm in post-monsoon and from 900 to 1200 μmhos/cm in pre-monsoon and monsoon seasons. The acceptable levels of DO, COD, and total coliform that were maintained in the river are proof that they correspond with WHO drinking water requirements. However, the study highlighted that continuous monitoring of the Ken River in the MP region is necessary to ensure its well-being (Awasthi et al. 2018).

Reflecting the geography of the Malwa Plain, the Chambal River is the main tributary of the Yamuna that flows through central MP (Khan 2022). At Janapao temple, about 24 km southwest of Mhow in MP, the river’s origins in the spectacular southern slopes of the Vindhya Mountains are reflected in its veins (Hussain et al. 2011). In addition to the river’s original upstream flow, three smaller streams, or nallahs, located next to the temple improve the river’s beauty and biodiversity (Saksena et al. 2008). Besides its pristine reputation, the river has a wide variety of aquatic species. These species include eight freshwater species such as turtles, skimmers, Gangetic River dolphins, and two species of crocodiles (gharial and mugger; Saksena et al. 2008).

Sohan thoroughly examined the chemical and physical properties of the Chambal River in the National Chambal Sanctuary in MP (Yadav et al. 2014). This sanctuary stretches over 600 km downstream from Kota to Yamuna confluence and is a buffer zone. The Chambal River in this sanctuary has been classified as Class C by the CPCB based on extensive data collected during 2003 and 2012. This classification indicates that the river in the sanctuary region is pollution-free and homely for a variety of aquatic plants and animals, including some endangered species. The findings highlight the success of conservation efforts in maintaining the ecological integrity and health of the Chambal River in this critical area (Yadav et al. 2014). These studies shed light on many of the dynamics of water quality in MP rivers and highlight the intricate interrelationships among various natural processes that sustain the Yamuna.

This section explains how the Chambal River being a tributary to Yamuna flows through MP. This river is free from pollution and is home to a variety of aquatic species. Several tests have been done to prove how good this river is. The next section deeply explains the observation of water concerning the period of COVID-19. Urbanization degraded Yamuna River's water, but COVID-19 lockdowns unexpectedly improved it.

Observations of water quality with respect to period of COVID-19

Scientists globally have extensively studied the quality of the Yamuna River water, recognizing a concerning decline attributed to industrialization, urbanization, and modifying land use patterns over recent decades (Thakur et al. 2018; Dudeja et al. 2011). However, an unexpected turn of events occurred with the outburst of the Coronavirus Disease (COVID-19) in late 2019, causing widespread disruptions (Awasthi et al. 2021). This global health crisis inadvertently led to positive changes in the water quality of the Yamuna River, particularly during and after lockdowns implemented in India. (Arora et al. 2020).

In the wake of the COVID-19 epidemic, lockdown measures brought industrial activities to a dead end, resulting in a remarkable improvement in the Yamuna River's surface water qualityThe Yamuna section of Delhi's WQI drastically improved, according to Patel et al. (2020), with notable decreases in COD and BOD of 39.3% and 42.8, respectively, and a 40% decrease in faecal coliform (Patel et al. 2020). Other research, such as the one on the Yamuna tributary Assan River by Arora et al. (2020), confirmed similar positive trends. Improvements in pH, TDS, and EC were seen at many test locations in the research (Arora et al. 2020). Arif et al. (2020) also observed notable decreases in the EC, pH, BOD, DO, and COD levels in Delhi's Yamuna River during the shutdown (Arif et al. 2020).

Singh et al. (2020) addressed how crucial Yamuna River water quality parameters were impacted by economic decisions. Their findings verified that significant increases in water quality measures including TSS, BOD, and COD were positively connected with lockdown-induced activity elimination (Singh et al. 2020). Studies done after 2019 consistently show the impaired status of the Yamuna River's water quality, which is further supported by the data summary in Table 8 and the observed positive trend. However, it is crucial to note that even during the lockdown period, challenges persisted, with untreated sewage flow identified as a significant concern (Patel et al. 2020; Ahmed et al. 2021). This emphasizes the ongoing need for effective wastewater management and domestic sewage treatment to sustainably address water pollution.

Table 8 Various research studies on Yamuna River from 2019to 2023
Full size table

To fulfil the primary goal of the present review paper, i.e. to discuss the different investigations that assess the water quality of the Yamuna, a thorough search was taken forward using the electronic search engine “ScienceDirect” by using the keyword “Yamuna” and organized in Table 8. Only peer-reviewed research publications written in English and published between 2019 and 2023 (after the first lockdown of the COVID-19 pandemic) were chosen for the present investigation by considering the keyword "Yamuna" as “title only” from the advanced search option of ScienceDirect's search platform. Initially, 67 articles were extracted, which were reduced to 25 articles by choosing the years “2019–2023” and the article type as “research articles”. Four articles were eliminated manually because of their irrelevancy concerning the goal of the review, and finally, 21 articles are summarized bibliographically in Table 8.

In Table 8, recent studies, spanning 2019–2023, consistently portray a grim picture of the Yamuna water quality. The studies mentioned in the table indicate a related pattern of degradation of water quality in the Yamuna. Several contaminants, encompassing HMs (Ahmed et al. 2022), and organic micropollutants (Mishra et al. 2023) cause serious risks to both aquatic ecosystem and human health (Ahamad et al. 2019). Pharmaceutical remains, which are the emerging contaminants, were detected even in the lightly inhabited upstream Himalayan areas (Biswas and Vellanki 2021). Results indicate that pollution problems affect not just heavily populated metropolitan areas but also the purer river regions. Ahmed et al. (2021) found that untreated sewage flow into the Yamuna River is still a serious issue (Ahmed et al. 2021). Domestic sewage persisted in increasing water pollution, even with the absence of industrial effluents during the COVID-19 lockdown period (Patel et al. 2020) which emphasizes the requirement of management sources and thorough domestic sewage treatment. One of the investigations used Remote Sensing (RS) and the Geographical Information System (GIS) for the identification of the artificial groundwater recharge site that helps in balanced water resource management (Khan et al. 2020). Overall, Table 8 highlights the increasing water quality disputes involving organic microplastics and HMs, emphasizing the critical need for conservation and water pollution control strategies to protect the Yamuna River water resource and its ecosystem. In the coming section, different management, and treatment strategies to control and purify the wastewater will be discussed.

Management and treatment of wastewater

The Yamuna River, integral to the lifeline of cities such as Mathura, Delhi, Agra, and Etawah, poses severe pollution challenges resulting from rampant industrialization and urbanization, notably in key areas like Mathura, Delhi, and Agra (Mishra 2010). To address this crisis, a bottom-up approach is deemed more effective than a top-down one. Rehabilitation efforts demand a multifaceted strategy, encompassing education, heightened public awareness, and improved watershed management. Key actions critical to enhancing Yamuna’s water quality include bolstering environmental management, refining agricultural practices, optimizing solid waste management, fostering water conservation, improving water use efficiency, allocating funds for wastewater management, promoting wastewater reuse and recycling, advocating wastewater treatment and technology, upgrading sewage treatment plants, and ensuring proper sewage disposal.

The global availability of clean water, essential for ecosystem development and socioeconomic sustenance, faces rapid depletion (Wu et al. 2019). Wastewater, stemming from various sectors, like households, industries, and municipalities, is a significant contributor to freshwater challenges (Hafeez et al. 2021). A staggering 56% of the 3928 km3 of freshwater withdrawn annually worldwide is released as untreated wastewater, underscoring the severity of the issue (Morali et al. 2016).

Wastewater treatment is pivotal for sustaining renewable water resources and fostering financial growth at the state level (Shehzad et al. 2020). Unfortunately, this truth often goes underappreciated and underutilized. Almost 2/3rd of the worldwide population grapples with severe water shortages for at least one month each year, exacerbated by a lack of incentives for industries to treat wastewater and ineffective enforcement of pollution control rules by local governments (Hafeez et al. 2021). An integrated strategy, incorporating affordable and sustainable technologies, is imperative to bolster the inclination towards effective wastewater treatment (Hassan et al. 2020).

Wastewater discharges into rivers not only exacerbate water shortages but also contribute to waterborne infections and adversely impact ecosystems and marine life. The management and treatment of wastewater play a crucial in mitigating these challenges by reducing or eliminating sediments, organic matter, disease-causing organisms, nutrients, and other contaminants before the treated water is released back into river ecosystems (Mishra 2010). Effective wastewater management is, therefore, an indispensable component of safeguarding both water resources and the health of river ecosystems. The upcoming section addresses the limitations of this review, serving as potential research gaps for future studies.

Limitation

Although this review study offers insightful information about the River Yamuna’s water quality, certain inherent limitations should be noted. Data on water quality may be limited over the complete stretch of the River Yamuna, with certain areas having more comprehensive data than others. Due to the numerous and frequently related pollution sources present along the Yamuna River, pinpointing the exact root cause of pollution can be difficult. Although the review discusses the possible effects of HMs on human health, more scientific studies are necessary for a more thorough health impact evaluation. The amount of thorough research on the water quality of the river Yamuna may be constrained regardless of the inclusion of studies from many states, especially in some areas and some regions that still need to be studied. Although the study emphasizes the significance of wastewater management, it is still necessary to consider the challenges of establishing and maintaining effective wastewater treatment systems across various geographic locations.

Conclusion

The Yamuna River's dire situation necessitates swift action and strict regulation to save the millions of people who depend on its waters as well as the river's natural health. The intricacy of the problem at hand is highlighted by the variety of pollution sources, ranging from untreated home sewage to industrial discharge and agricultural runoff. However, comprehensive policies that systematically target important areas—this report primarily focuses on industrial regulations, wastewater management, sustainable agriculture practices, and campaigns—also provide optimism. These key concepts offer an integrated approach to addressing the river's numerous issues and are crucial cornerstones for restoring the Yamuna River. The management strategies will not only help decision-makers to restore the water quality of the river Yamuna but also all the rivers.

Wastewater management is critical in developing efficient sewage treatment plants (STPs) and decentralized wastewater solutions. This plan attempts to deal with the widespread untreated wastewater outflow, which accounts for a significant 80% of surface water pollution. Cities like Delhi are particularly affected by this problem. Enforcing strong industrial limits is essential to reduce pollution at the same time. When coupled with incentives for greener production methods, these policies should reduce the number of HMs like Cr and other pollutants from unregulated enterprises like Wazirpur. By ensuring that companies adhere to environmentally friendly practices, the impact on the Yamuna's water quality may be reduced. To reduce the high nitrate and phosphate concentrations that lead to eutrophication and fish mortality in the river, it is essential to promote sustainable agricultural practices, mainly through the adoption of organic farming techniques. It is possible to significantly reduce the quantity of hazardous nutrients that enter the Yamuna by using fewer chemical fertilizers and switching to ecologically friendly farming methods. Programs that raise public awareness are essential for simultaneously encouraging a sense of accountability and active participation. Through cleanup initiatives and reporting mechanisms for identifying and penalizing offenders, these programs aim to create a common commitment to maintaining  the river's health. The sense of accountability and ownership generated by citizen engagement ultimately determines how successful more considerable  environmental conservation efforts are.

Recognizing the significance of the four primary concerns outlined above, it is evident that the improvement in Yamuna water quality during the COVID-19 lockdowns acts as a sore reminder of what happens when policy interventions are carried out systematically. However, these initiatives must cover more land than simply major cities; they must also address knowledge gaps and sources of contamination in the river's upper reaches, including states like the UK and HP. Preserving the ecological integrity of the Yamuna requires concerted action across political boundaries and socioeconomic groups. This collaborative effort is built upon a foundation of comprehensive scientific research, well-informed policy based on local realities, and grassroots behaviour change mobilization. The restoration of the Yamuna essentially requires a paradigm shift in our relationship with this significant river. Even though it is frequently seen as merely a trash conduit, it plays a crucial role in a variety of ecosystems. To protect the environment for the benefit of present and future generations, people must work together as stewards of these historic rivers to restore their purity.

Future perspective

The Yamuna River is regarded as the spiritual lifeline for millions of Indians. It does, however, currently face an environmental catastrophe that calls for immediate action as well as substantial regeneration initiatives. Subsequent research is sparked by recent foundational studies that pinpoint important knowledge gaps and rank areas that require urgent attention. Understanding the different causes of pollution, such as untreated sewage and industrial effluents, is crucial to developing targeted and successful regulations and cleaning initiatives. Technological developments, especially in the field of artificial intelligence, offer novel instruments for analysing pollutants in rivers such as the Yamuna. Machine learning algorithms are trained on large datasets to help them detect new threats and anticipate when action is most likely to be needed.

The Yamuna's surrounding industrial activities and constant urbanization make longitudinal research essential. These studies provide insightful information on the temporal patterns that affect the river's health over extended periods. The ability of contemporary sensors to identify pollution instantaneously gives real-time solutions and has a lot of potential. By acting as early warning systems that alert authorities to potential threats, these innovations have the potential to drastically alter the way water quality is managed. A paradigm shift towards environmental stewardship is demonstrated by preventive actions such as these, which prioritize prevention over cure—a crucial stance for the long-term, sustainable preservation of natural resources.

This study focuses on directing efforts to restore an ecosystem that was previously flourishing but is now burdened with obstacles caused by people. It also actively establishes strategic paths for future research, pointing out knowledge gaps. Worldwide efforts for environmental conservation, which emphasize the value of safeguarding natural resources like the Yamuna River for future generations as well as the feelings of those who regard the river as sacred, are in harmony with our initiative.