Water sparing versus sharing: Depolarising wetland management with novel environment-agriculture policy

Land sparing centres on agricultural intensification to increase yields and free land for conservation, while land sharing integrates farming and biodiversity but needs larger areas. Although the debate has matured to consider social-ecological systems and potential synergies, water has been almost entirely neglected. We develop a ‘water sparing versus sharing’ concept, propose new water sharing policies, and assess public values towards them in Australia's Murray–Darling Basin. Here, water sparing dominates and fuels polarised debate, especially around environmental water recovery, where increased conservation—typically in protected areas—occurs while farming becomes more intensive and water-efficient. Conversely, we introduce water sharing, which transcends this binary approach and, under certain conditions, could offer greater environmental, economic and social benefits. We show that water sharing challenges the key premise of land sparing because additional water to integrate biodiversity can increase yields, requiring less land. We illustrate our arguments with three policy options to conserve threatened species dependent on both traditional rice farming and natural wetlands supported by environmental water: (1) amalgamating environmental and irrigation water; (2) using environmental water in artificial refuges; and (3) subsidising water to incentivise multifunctional benefits. Using biodiversity benefits per megalitre, alongside social and economic metrics, scenarios could be prioritised. A survey of Australians ( n = 1478) showed strong public support for such amendments. A multinomial logit model indicated younger people with higher environmental values and lower incomes were most supportive. Water sharing policy can depolarise management, maximise multifunctional water-use efficiency and offer a political conduit between conflicting interests.