Andhra Pradesh Chief Minister N Chandrababu Naidu inaugurated Phase-1 of the Poola Subbaiah Veligonda Project on August 31, 2026, releasing 10.7 TMC of Krishna River water into the Nallamala Sagar reservoir. Operating entirely through gravity via massive twin tunnels drilled under the Nallamala Tiger Reserve, the project draws water from the Srisailam backwaters. It aims to irrigate 1.19 lakh acres, provide drinking water to 4 lakh people, and eradicate severe fluoride contamination in the drought-prone Prakasam and surrounding districts.
On August 31, 2026, Andhra Pradesh Chief Minister N Chandrababu Naidu officially inaugurated Phase-1 of the Poola Subbaiah Veligonda Project. He lifted the feeder canal gates, allowing 10.7 TMC of Krishna River water to flow into the newly built Nallamala Sagar reservoir. The immediate trigger was the urgent need to provide surface water to the severe drought-hit and fluoride-affected regions of western Prakasam and Markapuram districts.
The inauguration took place on August 31, 2026. The water transfer originates at the Kollam Vagu inlet in the backwaters of the Srisailam Reservoir and travels horizontally across the Nallamala Hills, terminating at the Nallamala Sagar reservoir in Andhra Pradesh.
1. Water is drawn from the Kollam Vagu inlet located at an elevation of 261 metres above sea level.
2. It flows through massive twin 18.8-km tunnels carved directly through the core of the Nallamala Hills.
3. Because the receiving Nallamala Sagar reservoir is lower (214.3 metres), water travels entirely via natural gravity flow.
4. The stored water is then routed through the Eastern Main Canal and Teegaleru canal to agricultural fields without the need for mechanical pumping.
India heavily relies on energy-intensive lift irrigation (like the Kaleshwaram project) to move water against steep terrains. Globally, large-scale gravity-fed inter-basin transfers are rare due to topographical hurdles. Veligonda is unique because it achieved this by drilling 18.8-km tunnels straight through one of India's most ecologically sensitive tiger habitats, relying on imported tunneling technology.
Core Concept: Krishna River System & Basin Management
Q1. Which river's water is being diverted under Phase-1 of the Poola Subbaiah Veligonda Project? [Easy]
A) Godavari
B) Krishna
C) Pennar
D) Cauveri
Answer: B
Explanation: The project taps into the backwaters of the Srisailam Reservoir, which is built across the Krishna River.
Q2. What is the primary objective of diverting water into the Nallamala Sagar reservoir? [Easy]
A) Generating hydroelectric power
B) Providing relief to drought-prone and fluoride-affected areas
C) Facilitating inland water navigation
D) Supplying cooling water to coastal thermal plants
Answer: B
Explanation: The project specifically aims to irrigate 1.19 lakh acres and tackle severe fluoride contamination in western Prakasam and Markapuram districts.
Q3. The Veligonda Project relies on which operational mechanism to transfer water from Kollam Vagu to Nallamala Sagar? [Moderate]
A) Large-scale lift irrigation using heavy electrical pumps
B) Pure gravity flow through twin tunnels
C) Reverse osmosis displacement
D) Submarine pipelines across the Bay of Bengal
Answer: B
Explanation: Because the Kollam Vagu inlet (261m) is higher than the Nallamala Sagar (214.3m), water flows entirely by gravity, avoiding recurring pumping costs.
Q4. The twin tunnels of the Veligonda project were drilled through which ecologically sensitive geographical feature? [Moderate]
A) Western Ghats Biosphere Reserve
B) Nallamala Hills and Tiger Sanctuary
C) Nilgiri Shola Forests
D) Seshachalam Biosphere
Answer: B
Explanation: The 18.8-km tunnels were carved through the core of the Nallamala forest, requiring complex engineering to protect the tiger sanctuary.
Q5. Which constitutional article empowers the Parliament to adjudicate disputes concerning inter-state river waters like the Krishna? [Moderate]
A) Article 262
B) Article 263
C) Article 280
D) Article 356
Answer: A
Explanation: Article 262 deals with the adjudication of disputes relating to the waters of inter-state rivers or river valleys.
Q6. Consider the impact of the Veligonda project on western Prakasam district. Which of the following public health crises does the project directly aim to mitigate? [Tricky]
A) Arsenic poisoning
B) High salinity induced hypertension
C) Severe fluoride contamination and fluorosis
D) Endemic Japanese Encephalitis
Answer: C
Explanation: Western Prakasam suffers from severe fluoride contamination in its groundwater, which the surface water supply will mitigate.
Q7. What was the unique environmental and engineering intervention adopted during the excavation of the Veligonda tunnels to minimise disturbance to the tiger reserve? [Tricky]
A) Halting all construction during the monsoon breeding season
B) Using a 19-km conveyor belt network to transport excavated muck
C) Using only manual labour for all 18.8 km
D) Constructing overhead ropeways for transporting heavy machinery
Answer: B
Explanation: A 19-km conveyor belt system was installed to transport excavated rock and mud, heavily reducing heavy vehicle movement in the tiger sanctuary.
Q8. Under which central scheme is the drinking water component of the Veligonda project being integrated to provide tap water by March 2027? [Tricky]
A) AMRUT 2.0
B) Jal Jeevan Mission
C) Swachh Bharat Abhiyan
D) Pradhan Mantri Krishi Sinchayee Yojana
Answer: B
Explanation: A 1.75 TMC drinking water component under the Jal Jeevan Mission is tied to the project to provide household taps to five assembly constituencies.
PYQ 1:
Which of the following reservoirs is the immediate source of water for the Poola Subbaiah Veligonda Project?
A) Nagarjuna Sagar
B) Srisailam
C) Pulichintala
D) Almatti
Answer: B
Explanation: The project draws 10.7 TMC of water directly from the backwaters of the Srisailam Reservoir via the Kollam Vagu inlet.
PYQ 2:
Consider the following statements regarding the Veligonda Project:
1. It aims to transfer surplus floodwater from the Godavari River to the Krishna River basin.
2. The water conveyance relies entirely on gravity flow without the need for mechanical pumping.
3. The project addresses severe groundwater fluoride contamination in parts of Andhra Pradesh.
Which of the above statements is/are correct?
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2, and 3
Answer: B
Explanation: Statement 1 is incorrect because the project transfers water from the Krishna River (Srisailam), not the Godavari. Statements 2 and 3 are factually accurate.
PYQ 3:
Assertion (A): The Veligonda Project involves significantly lower recurring operational costs compared to many modern inter-basin transfer projects like Kaleshwaram.
Reason (R): The water flows from the Kollam Vagu inlet to the Nallamala Sagar reservoir entirely through gravity.
A) Both A and R are correct, and R is the correct explanation for A.
B) Both A and R are correct, but R is not the correct explanation for A.
C) A is correct, but R is incorrect.
D) A is incorrect, but R is correct.
Answer: A
Explanation: Because the Kollam Vagu inlet is higher (261m) than the reservoir (214.3m), gravity alone drives the flow, eliminating expensive electricity pumping costs.
Question 1 (150 words): How does the Poola Subbaiah Veligonda Project address the dual challenges of water distress and public health in Andhra Pradesh?
Fulfilling a long-standing demand, Phase-1 of the Poola Subbaiah Veligonda project was inaugurated in August 2026 to deliver 10.7 TMC of Krishna water to parched regions. It tackles state-level challenges on two critical fronts: agrarian distress and public health.
On the agricultural front, the project brings assured surface irrigation to 1.19 lakh acres in drought-prone areas like Prakasam and Markapuram. By providing surface water, it heavily reduces reliance on depleted groundwater aquifers, encouraging crop diversification and halting distress migration.
On the public health front, districts like western Prakasam suffer from endemic fluoride contamination in groundwater, leading to crippling skeletal fluorosis. Assured surface water, combined with a 1.75 TMC allocation under the Jal Jeevan Mission targeted for March 2027, will supply safe household tap water to nearly 4 lakh people. Ultimately, such gravity-fed inter-basin transfers serve as robust models for climate-resilient water and health security.
Question 2 (250 words): "Inter-basin water transfers like the Veligonda project are engineering marvels but come with complex ecological, economic, and interstate challenges." Critically analyse this statement in the context of the Krishna River basin.
The inauguration of Veligonda Phase-1 in August 2026 marks a historic milestone in India’s water management, transferring Krishna waters through massive 18.8-km tunnels to drought-prone upland districts in Andhra Pradesh. While a lifeline for parched regions, it highlights the immense complexities of modern mega-engineering.
Economically and technically, the project is a marvel. By relying entirely on gravity flow from the 261-metre high Kollam Vagu to the 214.3-metre Nallamala Sagar, it permanently avoids the massive electrical costs associated with lift irrigation. However, such projects demand heavy capital; the NDA government had to infuse over ₹2,400 crore in just the last two years and clear ₹768 crore for 6,206 displaced families to accelerate completion.
Ecologically, the challenges were severe. The twin tunnels traverse the fragile Nallamala hills and a notified tiger sanctuary. Excavation faced heavy groundwater seepage and mud traps. It necessitated novel environmental solutions, such as a 19-km conveyor belt, to transport excavated muck without disturbing the protected wildlife via heavy vehicular traffic.
Politically, interstate challenges loom large. The Krishna basin, governed by Article 262 and monitored by the Krishna Water Disputes Tribunal, is highly sensitive to monsoon deficits. The bifurcation of Andhra Pradesh has heightened tensions with Telangana over the Srisailam reservoir, the very source of Veligonda’s water.
While Veligonda promises immense relief from water scarcity and fluoride contamination, ensuring sustainable water levels at Srisailam amidst erratic El Niño cycles remains the ultimate test. Future policies must harmonise large-scale engineering with holistic basin-level climate resilience.