The prospect of increasing water scarcity, as a result of continued population growth and a changing climate, makes improvements in the way societies account for water an imperative. Water accounting—the measurement, processing, and communication of information on water availability and use—is essential for effective and sustainable water resource management. It facilitates transparent, flexible, and efficient water allocation decisions for the benefit of the economy and environment, and reduces conflicts among users. This is especially crucial in dry regions such as the western United States, where water demands often outstrip available supplies.
Using a web-based review of water accounting practices, supplemented with interviews of more than 35 experts, in this paper we comparatively analyze how 12 western states and 2 countries—Australia and Spain—gather, process, and share information to manage water resources. We focus on how water availability is assessed; how varying institutional and legal frameworks define different water claims; how water use is measured or estimated; how water allocation decisions are made based on regulatory and physical constraints and available information; and finally how the information is shared to improve stakeholders’ decision making.
To conclude, and drawing on the comparative review, we select management practices for strengthening water accounting. Although these lessons are based on places that share resource-management challenges common to advanced economies, they can be useful for implementing new policies in developing regions to avoid common conflicts such as managing groundwater sustainability, dedicating adequate water to support the natural environment, or allocating surface water during periods of scarcity.