Equitable Apportionment of Inter-State River Waters

The doctrine of equitable apportionment requires inter-State river waters to be shared fairly among basin States according to their legitimate needs and circumstances. It means equality of rights, not an equal mathematical division of water or an absolute right based solely on territorial location, prior use, or contribution to the river.

Core requirements

Equitable apportionment treats an inter-State river basin as an interconnected hydrological system. Every riparian State is entitled to a reasonable share, but must exercise its rights without unfairly impairing the corresponding rights of other States.

• An upstream State cannot claim exclusive ownership merely because water flows through its territory.
• A downstream State cannot demand that all existing uses remain permanently protected regardless of changing legitimate needs.
• The allocation must reconcile competing claims through fairness, reasonableness, and basin-wide assessment, rather than political or territorial dominance.
• Equity may require sharing shortages as well as benefits, depending on the governing award or agreement.

Factors guiding allocation

There is no universal numerical formula. Tribunals and courts consider relevant circumstances together and assign them appropriate weight.

• Physical factors include basin geography, hydrology, rainfall, water availability, and contribution from different catchments.
• Human factors include population dependence, drinking-water requirements, irrigation, existing uses, economic needs, and feasible alternatives.
• Efficiency considerations include avoiding waste and promoting beneficial and economical use.
• Environmental requirements and the need to preserve the river system may also influence a sustainable allocation.

Constitutional and statutory setting

Under Article 262, Parliament may provide for adjudication of disputes concerning inter-State river waters and may exclude the jurisdiction of courts over such disputes. Parliament enacted the Inter-State River Water Disputes Act, 1956, under which tribunals determine disputes and their decisions are published and binding.

• Water is primarily in State List Entry 17, subject to Union control under Union List Entry 56 over inter-State rivers and river valleys when Parliament declares such control expedient in the public interest.
• In the Cauvery judgment, 2018, the Supreme Court applied equitable apportionment as the governing principle for balancing the rights and needs of basin States.

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