In the Western United States, demand for water is often out of balance with limited water supplies. This has led to extensive water rights conflict and litigation. A tool that can reliably forecast natural aquifer discharge months ahead of peak water demand could help water practitioners and managers by providing advanced knowledge of potential water‐right mitigation requirements. The timing and magnitude of natural aquifer discharge from the Eastern Snake Plain Aquifer (ESPA) in southern Idaho is accurately forecast 4 months ahead of the peak water demand, which occurs annually in July.

An integrated biophysical and economic model is used to determine the effects of using more water efficient irrigation systems and trade in water rights on the environmental performance of irrigation enterprises in the Mooki catchment within the Murray–Darling Basin, Australia. We find that improved water use efficiency increased profit in the presence of modern irrigation technologies and water trading. Salinity risk downstream is reduced due to the fall in saline discharge from the catchment, and irrigation water is traded away from ecologically significant regions.

This paper re-visits the concept of water efficiency applied to Spanish agriculture and assesses how this technical concept is sometimes lost in translation when applied at different spatial scales. The paper traces the historical dominance of irrigated agriculture in Spanish water policy. It analyses the water efficiency concept at the macro level, by evaluating recent national policy initiatives and public investment programmes over the last decade to modernise irrigation, which anticipated large water savings.

Over the past 20 years, water reform has moved to clarify water rights and responsibilities among users, separated water and land management, and introduced markets. Most recently, water policy has clearly recognised the need for environmental allocations to ensure sustainability. These reforms, especially the last, have created conflicts between stakeholder groups.