The upper riparian state is a concept in water resource management and international law, referring to a state or province whose territory contains the upstream section of a shared river or watercourse, meaning the water flows through it before reaching a lower riparian state. For instance, in the Cauvery River dispute, Karnataka is the upper riparian state, while Tamil Nadu is the lower riparian state. The concept originated from the need to manage transboundary water resources, leading to the development of international guidelines like the Helsinki Rules on the Uses of the Waters of International Rivers, adopted by the International Law Association (ILA) in August 1966.
The core mechanism governing the relationship between riparian states is the principle of equitable and reasonable utilization. Article IV of the Helsinki Rules established that each basin state is entitled to a "reasonable and equitable share" in the beneficial uses of the waters. This principle was codified in the UN Convention on the Law of the Non-Navigational Uses of International Watercourses, adopted by the UN General Assembly on May 21, 1997, and entered into force on August 17, 2014. Article 5 of the UN Convention mandates that watercourse states utilize the shared resource "in an equitable and reasonable manner". Crucially, the upper riparian state is also bound by the duty not to cause significant harm to the lower riparian state, as stipulated in Article 7 of the UN Convention.
In the Indian context, this concept is central to disputes resolved under the Inter-State River Water Disputes Act, 1956, such as the Krishna-Godavari dispute, where Maharashtra is the upper riparian state to Karnataka and Andhra Pradesh. While the Helsinki Rules were superseded by the Berlin Rules on Water Resources in 2004, the fundamental principle of equitable utilization has remained the cornerstone of international water law.