The Ganga basin has an extremely high density of population. This dense population, coupled with high growth rate is expected to generate huge demand for additional water in Ganga basin. Further, industries are rapidly growing in the region. The  increasing level of pollution from urban and industrial areas has created a sharp decline in the quality of Ganga water. The problem has arisen largely due to the discharge of untreated urban wastes and industrial effluents from the cascade of large and medium cities located along the course of Ganga and its tributaries. Although Ganga is considered as a holy river in mythology, people do not hesitate while dumping domestic and industrial waste in the river.

Numerous cities located in the Ganga basin generate and discharge huge quantities of wastewater, a large portion of which eventually reaches the river through natural drainage system. The industrial complexes which have sprung up along the rivers also dump considerable pollution loads into the river. Over the years, the Ganga and its tributaries have become the channels of transport of industrial effluents and the drains for the wastewater of the cities. It is estimated that some 900 million litres of sewage is dumped into the Ganga every day; three-fourths of the pollution in the Ganga is from untreated municipal sewage. In particular the middle reach of the basin between Kanpur and Buxar is the most urbanized and industrialized, as also the most polluted segment of the basin. Municipal and industrial wastes with dangerous concentration find entry into the watercourse in this segment and pose a grave threat to society.

In the hilly reaches up to Rishikesh, Ganga water is quite clean except for sediments. From Rishikesh onwards, disposal of sewage into Ganga begins. Besides the municipal waste of Rishikesh and Haridwar, industrial units discharge partly treated effluents into the river. Haridwar City has a population of 1.5 lakh and nearly 60,000 people visit the city every day on an average. This number rises to a few lakh on important religious days and may go up to 15 lakh on the auspicious days during Kumbha Mela (fair). Considerable lengths of sewer lines are clogged by silts that flow in from the adjoining hills.

Further downstream from Haridwar, Ganga flows through Bijnor, Garhmukteshwar, Narora and Kannauj. Here, water is not much polluted as these two towns do not have any large industry. A note worthy feature of this area is considerable quantity of baseflow that joins the river in this reach during the post-monsoon season. Moving downstream, the situation changes for the worse at Kanpur from the quality point of view.

The major polluting industries on the Ganga are the leather industries, especially near Kanpur, which use large amounts of Chromium and other chemicals and much of it finds its way into the meager flow of the Ganga. With the lax monitoring and enforcement by the government, the possibility of immediate control of pollution is limited. However, industry is not the only source of pollution. Sheer volume of waste – estimated at nearly 1 billion litres per day – of mostly untreated raw sewage – is a significant factor. Also, inadequate cremation procedures contribute to a large number of partially burnt or unburnt corpses floating down the Ganga. In addition, animal corpses can also be seen floating in the river. Sewage from the city (population 2.7 million) coupled with untreated toxic waste discharge from about 150 industrial units results in severe damage to water quality. The mean value of DO at 3 mg/l at Jajmau, near Kanpur, reflects the levels of pollution caused by discharge from 80 tanneries and other industries.

At Allahabad with population of more than a million, municipal wastes are the major contributor to river pollution. Yamuna whose water is highly polluted joins Ganga at Sangam. Large volume of municipal and industrial waste is dumped in the river at Varanasi, a city with approximately 1.2 million population, The Varuna River, which joins the Ganga in the vicinity of Varanasi, receives waste from many drains. Besides, due to the religious belief that those who die in Varanasi are sure to go to heaven, on average, more than 40,000 dead bodies are cremated on the river bank and the ashes and remains are dumped in the river.

The Water quality of River Ganga indicates that pH, conductivity and DO are meeting the water quality criteria at majority of locations. pH ranges from 5.9–9.1. Dissolved Oxygen ranges from 0.6 to 14.1 mg/l. Conductivity ranges from 18-6220 μmhos/cm. High value of conductivity is observed at Diamond Harbour (6220 μmhos/cm) due to intrusion of sea water in the estuary. The BOD value ranges from 0.4-27 mg/l. BOD is exceeding the water quality criteria at majority of the locations except at Gangotri, Upper Stretch of Rudraprayag, Devprayag and Rishikesh in Uttarakhand; Shukra Tal in Uttar Pradesh and whole stretch in Bihar except Bhagalpur and Ramrekhaghat.

The count of Faecal Coliform (FC) ranges from 21-3 x10⁶ MPN/100ml whereas Total Coliform (TC) ranges from 30-5 x10⁶ MPN/100ml. The maximum Total Coliform (TC) and Faecal Coliform (FC) level is not meeting the desired water quality criteria at most of the locations. The highest value of Total Coliform and Faecal Coliform is observed at Dakshineshwar. The concentration of Nitrate+Nitrite ranges from 0.0 -10 mg/l. The water quality of River Ganga with respect to Temperature, pH, Conductivity, DO, BOD, Nitrite+ Nitrate, Total Coliforms (TC) and Faecal Coliform (FC) is given here.

Water Quality of River Yamuna

The River Yamuna is a major tributary of River Ganges. In the upper course of 200 km stretch it draws water from several major streams namely Rishi-Ganga, Unta and Hanuman Ganga, Tons, Giri, and Ashan. The combined stream flows through the shivalik range of hills of Uttarakhand, Himachal Pradesh, and Uttar Pradesh and enters into the plains in the Dak Phatthar in Haryana where this river regulated through weir and diverted into canal for power generation. From Tajewala barrage in Yamunanagar district of Haryana, river again diverted into Western Yamuna Canal and Eastern Yamuna Canal for irrigation. River regain its water from ground water accrual and feeding canal through Somnadi (seasonal stream) just U/s of Kalanaur and traverses a route of about 1150 km through three states i.e. Haryana, Delhi and U.P. and finally to its confluence with Ganges at Allahabad. It receives major tributaries like Chambal, Betwa, Sindh and Ken from right bank and Hindon from left bank.

The availability of water in River Yamuna is greatly varied with time and space. Precipitation is confined to only three months in a year and varies greatly. Most of the water flows in the Yamuna (nearly 80%) in monsoon period (July, August and September) only. Whatever water flows in non-monsoon period (October to June) is extensively used for irrigation and drinking leaving very little or no water in the river to flow.

It is observed that about 500 km long stretch of the river is in bad shape, having water quality, most of the time, below desired level for "designated best use". In the dry season four distinct gradients of pollutional load can be discerned in the river stretch between Wazirabad and Etawah. The stretch between Wazirabad and Okhla is the most heavily polluted one, carrying the massive input of wastewater from Delhi. This input has sets off a progressive series of chemical and biological events in the D/s water. This stretch is characterised by high bacterial population, cloudy appearance high BOD and strong disagreeable odour - all indicating general depletion of oxygen. Masses of gaseous sludge rising from the bottom are often noticed floating near the surface of the water. During monsoon due to flood the sludge deposited in this stretch is flushed and stay in suspension causes rise in oxygen uptake in the D/s. This causes heavy fish mortality every year during first flushing after onset of monsoon.

Though there are number of bathing "Ghats along the river in Delhi stretch, the quality of water is far below the bathing standards. Even in this short stretch, remarkable purification takes place due to high temperature and long retention time in this stretch due to the two barrages one at Okhla and another at ITO (nearly 10 km U/s of Okhla Barrage). The ITO Barrage is used divert the Yamuna water for cooling purpose of the two Thermal Power Plants located near ITO. In the stretch between Okhla and Agra the same assimilative capacity can be observed after the sewage input at Okhla, Mathura and Agra. After a few kilometers the repeated additions of sewage are mainly noticeable by a higher state of eutrophication leading to the formation of algal mats in the River. Excessive algal can cause problems associated with the oxygen balance in the water (daytime super saturation and nighttime oxygen depletion). The water quality from DO, BOD, and bacterial point of view is not fit for designated best uses of this stretch. The Agra Water Works is drawing its raw water from this only.

The stretch from Agra to the confluence with the River Chambal at Etawah is characterized by self- purification processes of the Agra effluents. The confluence with relatively clean Chambal River is of great value in diluting the pollution load of River Yamuna before it joins the Ganga at Allahabad.

During the monsoon period due to huge mass of water flows in the river the barrages are opened leading to a more or less continuous system. The high load of untreated biodegradable material (domestic sewage) leads several gradients in saprobic and eutrophic conditions; major part of the Yamuna can hardly fulfill the designated uses.

Major Water Quality Segments

The Yamuna is classified into 5 distinct segments due to characteristic Hydrological and Ecological conditions. These segments are:

Critical Segments

The water quality in the Himalayan Segment and the Diluted Segment is comparatively good. However, due to heavy abstraction from and discharge of pollutants into the river system, there are critical segments, which require pollution abatement measures to improve the water quality of the river. These segments with the causes of pollution are:

Water Quality of River Yamuna

The water quality of River Yamuna with respect to pH ranges from 6.1 to 8.9. The conductivity is complying with desired water quality criteria at all locations and ranges from 52-1110. The DO varies from 0.0 to 11.4 mg/l. Supersaturation of DO indicates that the river is highly septic or eutrophicated at a number of locations. The low values of DO are observed at Nizammuddin, at Okhla bridge ,at Okhla after meeting of Shahdara drain,at Mazawali (0.0mg/l),at Mathura U/S (0.8mg/l) ,at Mathura D/S(1.5 mg/l) ,D/S Agra(1.6 mg/l) Shahpur (1.8 mg/l), Vishramghat Mathura (2.0 mg/l) and Kesighat Vrindavan (2.1 mg/l).

The BOD ranges from 0.8-113 mg/l in the entire length of river. The maximum value of 113 mg/l of BOD is observed at Okhla after meeting of Shahdara drain. The other locations observed maximum BOD are at Okhla Bridge (inlet of Agra Canal (40mg/l) ,at Nizzamuddin (39 mg/l), at Mazawali (24.0 mg/l),D/S of Agra and at Bateshwar (15mg/l) Vishramghat Mathura(14.6 mg/l), at Etawah (14.0 mg/l),Kesighat Vrindavan (13.8 mg/l) and Shahpur (12.8 mg/l).

Faecal Coliform value ranges from 6-2 x 10¹⁰ MPN/100ml whereas the Total Coliform value ranges from 12-2x10¹⁰ MPN/100ml. The Total and Faecal Coliforms count is considerably high and does not meet the criteria at most of the monitoring locations. The highest value of Faecal Coliform and Total Coliform is observed at Okhla after meeting Shahadara drain, Nizamuddin and Okhla Bridge (Inlet of Agra Canal). The concentration of Nitrate+ Nitrite varies from 0-2.58 mg/l. The water quality of River Yamuna with respect to Temperature, pH, DO, Conductivity, BOD, Nitrate +Nitrite, Total Coliform (TC) and Faecal Coliform (FC) is presented here.

The water quality status of mainstream of River Yamuna with respect to BOD, DO, Total Coliform, Faecal Coliform and Conductivity is given below:

Water Quality of tributary streams - Suswa, Gola, Bhalla, Dhela, Kosi Ramganga, Kalinadi (E), Varuna, Sai, Gomti, Rapti, Saryu, Ghaghara, Rihand, Sone, Gandak, Sikrana, Burhi Gandak, Harbora, Kamla, Manusmar, Koshi, Daha, Dhous, Farmar, Ram Rekha, Sirsa, Bagmati, Punpun and Sirsia

The water quality of tributary streams Suswa, Gola, Bhalla, Dhela, Kosi Ramganga, Kalinadi (E), Varuna, Sai, Gomti, Rapti, Saryu, Ghaghara, Rihand, Sone, Gandak, Sikrana, Burhi Gandak, Harbora, Kamla, Manusmar, Koshi, Daha, Dhous, Farmar, Ram Rekha, Sirsa, Bagmati, Punpun and Sirsia is conforming to water quality criteria with respect to conductivity throughout its length whereas pH is observed higher than the desired criteria at some locations.

The DO varies from 0.4 to 12.3 mg/l in mentioned rivers. DO is observed low with respect to desired water quality criteria in Dhela River D/s at Thakurdwara (0.4mg/l) & U/s Kashipur-Muradabad Road Bridge (0.8mg/l); Sushwa at Mothrawala (0.6 mg/l); Bhalla river at D/s Kashipur (0.8 mg/l) & U/s Kashipur (1.0 mg/l), Varuna before confluene to Ganga (1.2mg/l); Gomti at Lucknow D/s (1.2 mg/l); Ram Rekha at Harinagar (3.5mg/l); Sirsa at Ruxol (3.5 mg/l) and Sirsia at Ruxol ( Koeria Tola) (3.4 mg/l).

The BOD ranges from 0.9-94 mg/l in above mentioned tributary streams. The high BOD values were observed in Kalinadi (East) at Kharkhoda-Parikshit Garh Rd (94 mg/l) & Kannauj (Before Conf.) (9.4 mg/l); River Bhalla at Lohia Bridge D/s Kashipur (74 mg/l) & U/s Kashipur (60mg/l); River Dhela D/s at Thakurdwara (62mg/l) & U/s at Kashipur Moradabad Road Bridge (58mg/l); River Sushwa at Mothrawala (46 mg/l); River Varuna at B/c with River Ganga at Varanasi (16.9 mg/l) & Rameshwar, Varanasi (3.8 mg/l); Sirsia at Ruxol ( Koeria Tola) (15 mg/l); River Gomti at Lucknow D/s (11 mg/l), Jaunpur D/s (3.8 mg/l), Varanasi (9.6 mg/l) and Lucknow U/s (3.7 mg/l); River Rapti Rajghat, Gorakhpur (3.8 mg/l); River Sai at Jalalpur, Jaunpur (3.7 mg/l) & Unnao after Drain Outfall (3.5 mg/l); River Ramganga at Kannauj (B/c) (6.8 mg/l); River Ghaghara at Barhalganj (3.6 mg/l) and Deoria D/s (3.4 mg/l); Harbora River at Narkatiaganj (3.4 mg/l); River Ram Rekha at Harinagar (4.8 mg/l) and River Sirsa at Ruxol (12 mg/l).

The Faecal Coliform (FC) value ranges from 40 to 7x10⁵ MPN/100ml whereas the Total Coliform (TC) value ranges from 100 to 2x10⁶ MPN/100ml. The highest count of FC and TC is observed in River Kalinadi (East) at U/s of Gulaothi Town in Bulandsahar, at Kharkhoda-Parikshit Garh Rd, Meerut & at Kannauj (Before Conf.); River Gomti at Lucknow D/s, Jaunpur D/s & Varanasi; River Varuna B/c with River Ganga at Varanasi & at Rameshwar Varanasi; River Ramganga at Kannauj (Before Conf.); River Daha at D/s Sasamusa, Siwan & Mirganj; River Ram Rekha at Harinagar; River Sirsa at Ruxol; River Farmer at Jogbani; River Dhous at Madhubani; River Manusmar at Riga Sitamarhi; River Sai at Jalalpur, Jaunpur; River Harbora at Narkatiaganj; River Saryu at Ayodhya at Main Bathing Ghat and River Sirsia at Ruxol (Koeria Tola). The water quality of the tributary streams Suswa, Gola, Bhalla, Dhela, Kosi Ramganga, Kalinadi (E), Varuna, Sai, Gomti, Rapti, Saryu, Ghaghara, Rihand, Sone, Gandak, Sikrana, Burhi Gandak, Harbora, Kamla, Manusmar, Koshi, Daha, Dhous, Farmar, Ram Rekha, Sirsa, Bagmati, Punpun and Sirsia is presented here.

Water Quality of tributary streams- Tons, Ashwani, Batta, Giri, Pabbar, Kalinadi(W), Hindon, Tons (MP), Betwa, Kaliasot, Kolar, Chambal, Parvati, Gohad, Khan, Kshipra, Kali Sindh, Sindh, Bichia, Sankh, Jamuni, Sone, Banas, Chhapi and Ujad

The water quality of Tons, Ashwani, Batta, Giri, Pabbar, Kalinadi (W), Hindon, Tons (MP), Betwa, Kaliasot, Kolar, Chambal, Parvati, Gohad, Khan, Kshipra, Kali Sindh, Sindh, Bichia, Sankh, Jamuni, Sone, Banas, Chhapi and Ujad tributary streams is conforming to water quality criteria with respect to pH and conductivity at all the locations. River Chambal at Nagda D/s (11700 μmhos/cm), River Betwa at Nayapur D/s (7040 μmhos/cm) & Near Road Bridge Bhojpur (4820 μmhos/cm) is not meeting the desired water quality criteria for conductivity. pH is observed slightly higher than the desired criteria in river Betwa, Ashwani, Giri, Pabbar, Kolar and Kshipra at their few monitoring locations.

The Dissolved oxygen ranges from Nil to 18.4 mg/l. DO is observed Nil in River Betwa at Nayapur D/s and River Khan at Kabit Khedi. DO is also observed low in River Hindon at Saharanpur D/s (1.0 mg/l); River Kaliasoat near Road Bridge Mandideep (3.5 mg/l); River Chambal at Nagda D/s (3.5 mg/l) & Kota D/s (3.7mg/l); River Parvati before meeting River Chambal at Khatoli, Kota (3.1 mg/l); River Kali Sindh at Anicut of M/S CFCL Gadepan, Kota (3.0 mg/l) & Barod Rd Bdg, Kota (3.6 mg/l); River Banas near Newta Dam, Jaipur (1.2 mg/l) & Dhanari Dam near Swaroopganj- Sirohi (1.6 mg/l); River Chappi U/s Chappi Dam (3.1 mg/l) and River Ujad U/s Bhim Sagar Dam, Jhalawar (3.7 mg/l).

The BOD ranges from 0.1 to 80 mg/l. The maximum value (80 mg/l) of BOD is observed in River Hindon at Ghaziabad D/s. Other locations having high BOD are River Hindon at Sardhana Budhana Road, Vill. Baparsi (Meerut) (64 mg/l) & Saharanpur D/s (24 mg/l); River Chambal at Nagda D/s (50 mg/l), Nagda U/s (Water Intake Point) (4 mg/l), Kota D/s (2 Km. From City) (3.5 mg/l) & Gandsagar Dam Rampura (3.2 mg/l); River Khan at Kabit Khedi (50.0 mg/l); River Betwa at Nayapur D/s Mandideep (64 mg/l), Before Conf. Yamuna at Hamirpur (3.3 mg/l), Near Road Bridge, Bhojpur (8 mg/l), D/s after mixing of River Bais at Vidisha (8 mg/l) & Charantirghat, Vidisha(6.8 mg/l); River Kaliasot near Road Bridge Mandideep (6.4 mg/l); River Kshipra at Ramghat at Ujjain (18 mg/l), Siddhawat (D/s) (22 mg/l) & Trivenisangam (1 Km. D/s of Sangam) (30 mg/l); River Kali Sindh at Anicut of M/S CFCL Gadepan, Kota (26.9 mg/l) & Barod Road Bridge (7.7 mg/l); River Banas near Newta Dam, Jaipur (39.9 mg/l) & Dhanari Dam near Swaroopganj, Sirohi (8.4 mg/l); River Bichia, Bridge Govindgarh Road (5.8 mg/l); River Parvati before meeting River Chambal at Khatoli (15.4 mg/l) & A/c of Vindhyachal Nalla, Pilukhedi (3.9 mg/l); River Gohad (3.6 mg/l); River Kolar at Sehore (14 g/l) and River Chappi

U/s Chappi Dam (4.8 mg/l).

The Faecal Coliform value ranges from 0 to 2x10⁵ MPN/100ml whereas the Total Coliform (TC) value ranges from 1 to 5x10⁶ MPN/100ml. The highest value of Total Coliform is observed in River Kalinadi at Mujaffarnagar D/s whereas The highest value of Faecal Coliform is observed in River Hindon at Ghaziabad D/s & Sardhana Budhana Road, Vill. Baparsi (Meerut). The other locations which are not meeting the desired water quality criteria with respect to TC and FC are River Kalinadi at U/s of Muzaffar Nagar; River Betwa at Govind Sagar & B/c Yamuna at Hamirpur; River Chambal at Etawah B/c to Yamuna.

The concentration of Nitrate+Nitrite ranges from 0.0-11.6 mg/l. The maximum value of nitrate is observed in River Chappi at Chappi Dam. The water quality of tributaries mentioned above is presented here.

Water Quality of tributary streams- Damodar, Barakar, Rupanarayan, Dwarakeshwar, Dwarka, Silabati, Jalangi, Churni, Matha Bhanga, Kansi, Mayurkashi, Mahananda, Vindhyadhari and Jumar

The water quality of the tributary streams Damodar, Barakar, Dwarakeshwar, Silabati, Jalangi, Kansi, Mayurkashi, Mahananda, Bokaro and Jumar are meeting the water quality criteria with respect to pH, DO and conductivity except DO in River Mathabhanga at Gobindpur (0.3 mg/l); River Churni at Majhadia (0.5 mg/l) & D/s of Santipur Town (2.7 mg/); River Vindhyadhari U/s & D/s (0.6 mg/l); River Dwarka at U/s Tarapith (1.0 mg/l) and River Jalangi at D/s of Krishna Nagar (3.4 mg/l) and conductivity in River Damodar at Hooghly (17910 μmhos/cm); River Rupnarayan at D/s Kolaghat (3270 μmhos/cm) and B/c to River Ganga near Geonkhali (10430

μmhos/cm); River Vindyadhari U/s at Haroa Bridge (7310 μmhos/cm) and D/S at Malancha Burning Ghat (29500 μmhos/cm).

The BOD ranges from 0.4 to 19.8 mg/l. The highest value of BOD (19.8 mg/l) is observed in River Matha Bhanga, Gobindapur. River Damodar at most of the monitoring locations and River Mahananda; Dwarakeshwar; Dwarka; Churni; Jalangi; Kansi; Barakar; Jumar; Rupnarayan; Vindyadhari are exceeding the maximum level of BOD with respect to desired water quality criteria.

The Faecal Coliform (FC) value ranges from 4 to 5 x10⁶ MPN/100ml, whereas the Total Coliform (TC) value ranges from 8 to 9x10⁶ MPN/100ml. The highest value of Faecal Coliform and Total Coliform is observed in River Matha Bhanga, Gobindapur. Tributary streams in West Bengal exceeding the maximum level of FC and TC with respect to desired water quality criteria at most of the monitoring locations. The water quality of these tributaries is presented here.