The Ganga and the Yamuna: polluted stretches and river cleaning

Detail

1. Why these two rivers matter

• The Ganga flows about 2,525 km from its source to the Bay of Bengal [2].
• Its source is about 4,100 m above sea level [2]. It rises as the Bhagirathi from the Gangotri glacier (Gaumukh) in Uttarakhand. It takes the name Ganga at Devprayag, where the Bhagirathi meets the Alaknanda.
• It flows across Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal before it reaches the sea.

• Its basin holds about 40% of India's population [2]. So more people and towns depend on it, and more waste enters it.

• The Yamuna is the Ganga's longest tributary on the right bank.

• It rises at the Yamunotri glacier (Bandarpunch range, Uttarakhand).
• It flows past Delhi, Mathura and Agra. The Chambal joins it near Etawah in UP.

• It meets the Ganga at Prayagraj (the Sangam).

• Ganga pollution means the river's water is spoiled by untreated sewage, factory waste, farm chemicals, solid waste and religious offerings.

• Yamuna pollution means the same problem, made worse because very little fresh water flows in the river.
• NCERT's MCQ answer: the Yamuna is highly polluted.

2. Water-quality terms (needed to read any data)

• Dissolved oxygen (DO): the oxygen gas dissolved in water. Fish need it to breathe. More DO means a healthier river.
• Biochemical oxygen demand (BOD): the oxygen that bacteria use up while breaking down waste in water. A high BOD means a lot of sewage.
• Faecal coliform: bacteria that come from the gut of humans and animals. When they are found, it means human waste is in the water.
• Bathing-water standards (used since GAP-I) [2]:

Parameter	Limit for bathing water
BOD	not more than 3 mg/l
DO	at least 5 mg/l
Total coliform	10,000 per 100 ml
Faecal coliform	2,500 per 100 ml

3. Table 9.2 — polluted stretches (NCERT)

River	States	Polluted stretches	Main polluters
Ganga	Uttar Pradesh, Bihar, West Bengal	(a) downstream of Kanpur; (b) downstream of Varanasi; (c) at the Farakka barrage	Industries in towns like Kanpur (tanneries); domestic sewage of Kanpur, Prayagraj, Varanasi, Patna, Kolkata
Yamuna	Delhi, Uttar Pradesh	Delhi to its confluence with the Chambal (near Etawah); Mathura and Agra	Water taken out for irrigation by Haryana and UP; farm run-off; Delhi's domestic and industrial waste

4. How the Ganga gets polluted

• Kanpur's tanneries (leather industry):
• Hides are tanned with chemicals, mainly chromium salts.
• The waste water carries chromium, salts and rotting animal matter into the river.

• Result: the stretch downstream of Kanpur is one of the dirtiest on the river.

• City sewage:

• The big towns on the river (Kanpur, Prayagraj, Varanasi, Patna, Kolkata) produce more sewage than their treatment plants can handle.
• Untreated sewage reaches the river through open drains.

• Result: BOD and faecal coliform rise downstream of each city.

• Farakka barrage (Murshidabad district, West Bengal):

• A barrage is a low dam with gates. It holds back or diverts river water.
• Farakka sends part of the Ganga's water into the Bhagirathi–Hooghly to keep the Kolkata port working.

• Waste piles up in the slow water behind the barrage, and flow below it drops. So this stretch is polluted too.

• Other sources: cremation, dumping of flowers and idols, bathing during fairs (rituals), and fertiliser and pesticide run-off from farms.

5. How the Yamuna gets polluted

• Too little water to dilute the waste:
• At the Hathnikund barrage (Yamunanagar, Haryana), water is sent into canals for Haryana and UP.
• In Delhi, the Wazirabad barrage stores water for the city. Often no water is released below it in the lean season [5].

• Result: below Delhi the river mainly carries sewage, not fresh water.

• Delhi is the worst stretch:

• The 22 km from Wazirabad to the Okhla barrage (Reach III) is the shortest reach of the river. It is also the most polluted [5].
• Along this 22 km, BOD rises to 4.8–40 mg/l, against the bathing limit of 3 mg/l. This shows Delhi does not have enough sewage treatment capacity (CPCB data, reported 2021) [5].
• Of the 22 drains that were monitored, 14 (such as Najafgarh, Sonia Vihar, Shastri Park and Shahdara) were found untapped, meaning their sewage was not intercepted. They pour sewage straight into the river [5].

• The Najafgarh drain is Delhi's biggest drain. STP works in its catchment, from Dhansa to Keshopur, were approved at ₹344.81 crore [6].

• Toxic foam:

• Detergents and industrial waste in untreated sewage contain surfactants (soap-like chemicals) and phosphates.
• When this water tumbles over barrage gates such as Okhla, it churns up white foam.

• The foam is a sign of heavy pollution, not just of dirt.

• Farm run-off:

• Rain washes fertiliser and pesticide from fields in Haryana and UP into the river.

• These bring micro-pollutants: harmful chemicals that work even in very small amounts.

• Downstream, Mathura and Agra add their own sewage and industrial waste to a river that is already dirty.

6. Early cleaning efforts

• Ganga Action Plan (GAP-I, 1985): India's first river-cleaning programme [2][7].
• Main idea: intercept, divert and treat sewage. That means catching drain water before it reaches the river, sending it to a plant and cleaning it.
• It covered 17 towns in UP, Bihar and West Bengal, such as Haridwar, Kanpur, Varanasi, Patna and Kolkata [2].

• It slowed down how fast the water was getting worse, but its overall success was limited [7].

• GAP-II (1993): extended the work to the main tributaries: the Yamuna, Gomti, Damodar and Mahananda [7].

• It planned to cover 59 towns in five states: Uttarakhand, UP, Jharkhand, Bihar and West Bengal [7].

• Yamuna Action Plan (1993): a separate plan for the Yamuna. It was later carried on in more phases.

• National River (2008): the Ganga was declared India's National River.
• National Ganga River Basin Authority (NGRBA): set up by a central notification dated 20 February 2009 [7]. It planned for the whole river basin, not just separate towns.

7. The present set-up

• National Mission for Clean Ganga (NMCG): a registered society, set up in 2011.

• On 28 April 2011, the CCEA approved the World Bank–assisted National Ganga River Basin Project, costing ₹7,000 crore, with NMCG as the implementing society [7].

• National Ganga Council (2016): formed under the River Ganga (Rejuvenation, Protection and Management) Authorities Order, 2016. It replaced the NGRBA. NMCG is now its working arm.

8. Namami Gange Programme (approved June 2014)

• What it is: the Union government's flagship (main) scheme to clean and revive the Ganga and its tributaries.
• Aims (NCERT box):
• Sewerage treatment in towns along the river.
• Monitoring of industrial effluents. Effluent means waste water let out by factories.
• River-front development: ghats, crematoria and walkways.
• Afforestation (tree planting) along the banks to support biodiversity.
• River-surface cleaning: removing floating waste.
• Ganga Grams: villages on the bank, made free of open defecation and given proper waste disposal, in Uttarakhand, UP, Bihar, Jharkhand and West Bengal.

• Public awareness to stop pollution from rituals.

• Newer tools and goals:

• Hybrid annuity model (HAM) for STPs: the government pays part of the cost during building. The rest is paid over 15 years, only if the plant keeps working well. This links payment to results.
• Ecological flow (e-flow): the minimum amount of water that must stay in the river to keep it alive. These norms were notified in October 2018, and NMCG says they have been enforced [4].
• Arth Ganga: linking the river to the local economy, for example through natural farming, sale of sludge and treated water, and tourism.

• Biodiversity: protection of the Gangetic dolphin, gharial, freshwater turtles, otters and native fish [4].

  • Dolphin surveys covered 8,507 km on 28 rivers and counted 6,324 Ganges dolphins across India [4].
  • India's first Dolphin Rescue Ambulance was launched on 13 January 2026 at the Wildlife Institute of India, Dehradun [4].

• Namami Gange Mission-II: approved with ₹22,500 crore till 2026 [3].

• ₹11,225 crore is for older, ongoing projects. ₹11,275 crore is for new projects [3].

• NMCG aims for a total sewage treatment capacity of 7,000 MLD by December 2026 [8]. MLD means million litres per day.

• Progress:

• 218 sewerage projects worth ₹35,794 crore had been taken up, with a capacity of 6,610 MLD [9].

• 138 STP projects (4,050 MLD) were completed and running [9].

• Results:

• An early round of checks showed DO had improved at 27 locations, BOD at 42 and faecal coliform at 21 [9].
• A later round showed DO better at 39 locations. BOD fell at 42 locations and faecal coliform at 47 [10].
• Overall, DO has improved. But faecal coliform is still above the bathing limit on many stretches, because sewage is still not fully treated.

Prelims Hooks

• The Wazirabad–Okhla stretch in Delhi is only 22 km long but is the most polluted reach of the Yamuna [5].
• NCERT's polluted Ganga stretches: downstream of Kanpur, downstream of Varanasi, Farakka barrage. Trap: Haridwar and Rishikesh are not on the list.
• NCERT's polluted Yamuna stretch runs from Delhi to the Chambal confluence, plus Mathura and Agra.
• Kanpur → tanneries (leather industry) is the classic industrial polluter of the Ganga.
• Order of steps: GAP-I (1985) → GAP-II and Yamuna Action Plan (1993) → National River (2008) → NGRBA (2009) → NMCG society (2011) → Namami Gange (June 2014) → National Ganga Council (2016) → e-flow notification (Oct 2018).
• GAP-II tributaries: Yamuna, Gomti, Damodar, Mahananda [7].
• NMCG is a registered society, not a statutory body. It is the implementing arm of the National Ganga Council.
• Ganga Grams are in five states: Uttarakhand, UP, Bihar, Jharkhand and West Bengal. Trap: Haryana and Delhi are not included.
• Bathing-water standard: BOD ≤ 3 mg/l, DO ≥ 5 mg/l, faecal coliform ≤ 2,500 per 100 ml [2].
• The Farakka barrage is in West Bengal and sends Ganga water into the Bhagirathi–Hooghly.

Mains Points

• Causes are both spatial and seasonal. Water is taken out upstream at Hathnikund and Wazirabad. So the Yamuna below Delhi is mostly sewage in the lean season, and building STPs alone cannot clean it. E-flow (2018) has to be part of the answer (GS-I/III).
• Policy shift from GAP to Namami Gange:
• GAP worked town by town, and it failed because states did not run or pay for the plants.

• Namami Gange plans for the whole basin and uses HAM, so payment depends on results. It also adds biodiversity and Arth Ganga, and has a stronger structure under the 2016 Authorities Order (GS-III).

• Results are mixed:

• DO and BOD have improved at many points [10].
• But untapped drains such as Najafgarh, sewage that is not treated, and STPs running below capacity keep faecal coliform high.

• Missing links: house sewer connections, reuse of treated water and control of industrial effluents.

• Urban link: river pollution grows with fast urban growth, slums without sewers and weak solid-waste management. This ties into the Swachh Bharat Mission and AMRUT in an answer on urban waste.