The Australian Capital Territory (ACT) became a full participant in the Murray Darling Basin (MDB) Initiative in 1998. This opened the opportunity for the ACT to establish water trading arrangements with the other MDB member States. Provisions to facilitate this trade are currently being developed. In addition, the ACT is required to negotiate an initial “Cap” level with the other MDB members before water trading can begin. The Cap defines the amount of water resources for which each State has extractive rights, and is based on 1993/94 levels of water utilising development. This paper investigates alternative trading strategies that could be used to “build” Cap over time, and explores the implications for negotiation of the initial ACT Cap endowment.