A Commonwealth plan, four state systems.

Water entitlements in the Murray-Darling Basin are creatures of state law. Each Basin state issues its own licences, maintains its own register, applies its own trade approval rules, and uses its own product definitions. A trade within a state is one transaction; a trade across a border is a transfer between two registers with two approval processes and two sets of terminology for products that are economically similar and legally distinct.

Physical constraints sit on top of the administrative ones and are not the same thing. Delivery limits — most famously the Barmah Choke — restrict how much water can physically move past a point regardless of who owns it, so some trades cannot be delivered even when they are approved. This database is careful to keep those apart: a hydrological limit is not red tape, and a reform that ignored it would be selling something.

What is administrative is the duplication: separate registers that do not interoperate, separate approvals for one economic transaction, and separate product taxonomies that make comparison hard for anyone who is not a specialist.

That is the seventh instance of the partial-national pattern in this database, and it is unusual in one respect: unlike community housing registration or worker screening, there is no national scheme sitting alongside for the states to join. The Commonwealth plans the water and does not register it. See One economic transaction, two registers, two approvals.