The concept of ‘Indigenous cultural water’ has emerged in Australia's Murray–Darling Basin in the context of sweeping reforms to provide environmental water allocations for ecosystem conservation. We discuss the concept of cultural water, its origins, and its function as a means of representing and advancing Indigenous interests in a fully allocated and heavily developed river system. Cultural water remains a contested and ambiguous frame for policy, providing ample scope for conflict over appropriate goals, standards, and efficacy. We used Q methodology to elucidate the structure and content of perspectives on Indigenous cultural water as a prospective frame for policy. Our results illustrate distinct views on cultural water relative to distributive justice and restitution, the role of science and technical experts, and prospects for collaborative management. They also illustrate nuanced perspectives on the relation between cultural and environmental water management. Clarifying goals and reconciling divergent expectations around cultural water is likely to be an ongoing challenge. We note that uncertainty surrounding the concept may ultimately function to open discursive spaces to alternative perspectives and innovations, and this would be supported by contextual approaches, grounded in place-based prototyping.