Explained: Telangana’s Supreme Court challenge to Andhra Pradesh’s Polavaram irrigation project

Approved in 2009, Polavaram was permitted to divert 80 thousand million cubic feet (TMC) of water from the Godavari to the Krishna River through its canal system for use in the Krishna Delta. The project is governed by the Godavari Water Disputes Tribunal (GWDT) Award and technical clearances issued by the Central Water Commission.

However, Telangana alleged that Andhra Pradesh has exceeded that limit. According to the state, project infrastructure has been expanded to carry more than 200 TMC of water, with plans to scale this up to 300 TMC, through what is now called the Polavaram-Banakacherla Link Project or the Polavaram-Nallamalasagar Link Project. It is planned to transform Andhra Pradesh’s drought-prone Rayalaseema region into fertile land by transferring water from the Godavari and creating a reservoir.

Andhra Pradesh has maintained that the diversion involves only “flood” or “surplus” waters of the Godavari.

What Telangana pointed to, however, is the scale of the physical changes. It said the Right Main Canal, originally cleared for 12,254 cusecs, is being widened to 35,500 cusecs, while the capacity of the twin tunnels is being doubled from 20,000 to 40,000 cusecs. Telangana argued that these changes structurally enable much larger and sustained diversions.

Further, the bench had noted during the hearing that Karnataka and Maharashtra, though parties to the Godavari Award, were not made parties to the Telangana petition. Telangana thus withdrew its petition, but it could institute a suit involving all affected basin states.

What the law says

India’s framework for resolving interstate river disputes is based on the Inter-State River Water Disputes Act, 1956. Under this law, when states fail to resolve water sharing disagreements, the Union government can constitute a tribunal, whose award is final and binding, with the force of a SC decree.

It was under this law that the Krishna Water Disputes Tribunal (KWDT) and the Godavari Water Disputes Tribunal (GWDT) were constituted in 1969, following prolonged disputes among Maharashtra, Karnataka and Andhra Pradesh. Notably, the Krishna basin had become a deficit basin, and so any additional use by one state would reduce availability for others.

The tribunals quantified available water using a “75% dependability” standard. Here, the amount of water that the river is expected to provide consistently is considered, not 100%, because rivers vary year to year and planning for full availability would fail in dry years. It thus allocated specific shares per state through binding awards. The KWDT gave its final award in 1976, and the GWDT in 1980.

However, two clauses from these awards lie at the centre of the present dispute.

Clause IV of the GWDT Award allows states to divert any part of their allocated share of Godavari waters to another basin. Andhra Pradesh has often cited the clause to justify transfers from the Godavari to the Krishna.

However, Clause XIV(B) of the KWDT Award, also known as the “augmentation clause”, places a condition on such diversions. It states that if the waters of the Krishna are augmented by diversion from another river, no state can be prevented from claiming a proportionately larger share of Krishna water.

This means that once additional Godavari water is brought into the Krishna basin, upper-riparian states such as Karnataka and Maharashtra are legally entitled to demand a higher share. Karnataka has already invoked this clause, along with a 1978 inter-state agreement, to claim up to 112 TMC of Krishna water if Andhra Pradesh proceeds with its planned diversions.

This legal aspect is what makes the Krishna basin particularly sensitive. Under the original 80 TMC diversion from the Godavari, Telangana, as part of the undivided Andhra Pradesh, lost 35 TMC of 75% dependable Krishna water to Karnataka and Maharashtra. That loss was calculated and mandated by the tribunal’s sharing formula. Any increase in inflows triggers redistribution claims that directly affect downstream states such as Telangana.

Telangana’s legal challenge

Telangana had approached the SC under Article 32 of the Constitution (right to approach SC in case of fundamental rights being violated), arguing that the dispute is not about reopening water allocation, but about enforcing existing tribunal awards and statutory safeguards.

A key plank of the case is the Andhra Pradesh Reorganisation Act, 2014. Section 90 of the Act declares Polavaram a national project and places its regulation and execution under the control of the Union government. Telangana argued that only the Centre or the Polavaram Project Authority can propose modifications to the project.

While the Act provides that Telangana’s consent to Polavaram is “deemed”, the state argued that this consent applies only to the project as approved in 2009, and since Section 90(2) vests control exclusively in the Union, any unilateral expansion by Andhra Pradesh is not merely a dispute over consent but a violation of law.

The state has also relied on constitutional protections. It invokes Article 21 (right to protection of life and personal liberty), stating that unauthorised diversion of water will deprive its residents of their share of river water, affecting drinking supply, irrigation and livelihoods in drought-prone areas.

It has also cited Article 300A, which says that no person shall be deprived of their property, save by the authority of law. It argued that the water allotted to it under binding tribunal awards is a legal entitlement, and that Andhra Pradesh’s unilateral expansion of the Polavaram project amounts to taking that share without legal authority.

Beyond allocation, Telangana has raised concerns about submergence and safety. It said that the unauthorised expansion alters how the Polavaram reservoir is operated. To support larger diversion and power generation, the reservoir would need to be held at a higher level for longer periods during the monsoon.

This creates cascading effects and drainage congestion within its territory. Local streams are unable to discharge into the river, leading to prolonged inundation. In this context, the state argued that areas such as the Bhadrachalam Temple town, the Manuguru Heavy Water Plant and several villages face risk from the sustained changes in the reservoir.