Agricultural and water development in the Krishna basin in south India has led to a progressive over-commitment of water resources. Based on a historical water accounting (1955–2004), this paper shows that upstream water development is the main cause for declining water availability in the lower Krishna basin (Andhra Pradesh state). But Andhra Pradesh's own policies of water resources development are also key in understanding the process of over-commitment observed in the region. To slow down basin closure (little or no discharge to the ocean), there is a need for formal and adaptive water allocation mechanisms that can internalize social and environmental objectives.