In arid counties, such as Australia, the storage and extractive use of water is causing significant environmental damage and traditional economic objectives of efficiency and maximising financial returns from surface water resources are often at conflict the long-term sustainability of riverine ecosystems. Policy options for acquiring water to improve environmental flow regimes include (a) reducing announced allocations, (b) recouping a proportion of traded water, and (c) have the government enter the market and purchase water. This article makes a contribution to environmental water policy by quantitatively evaluating and comparing these policy options for restoring environmental flow regimes. A case study of the Murrumbidgee Catchment located in New SouthWales, Australia is used to highlight the conflicts and tradeoffs between water management objectives in fully allocated arid river basins.