The history of water management in Iran is both extensive and filled with ups and downs. This chapter analyses this part of Iran’s history across four key periods: pre-Islamic antiquity, the Islamic golden age, the Pahlavi modernisation era, and the post-1979 Islamic Republic. Rather than offering a conventional political chronology, it focuses on shifting hydro-social imaginaries—the evolving ways water has been understood, valued, and materially organised. It argues that Lake Urmia’s ecological crisis is not an isolated recent failure but the outcome of long-term socio-political and ontological transformations in human–water relations in Iran. In antiquity, water held a sacred place in Zoroastrian cosmology, linked to the goddess Anāhitā, and was central to both spiritual life and large-scale hydraulic systems. Successive invasions and imperial decline fragmented these systems and eroded communal water institutions. The Pahlavi regime’s twentieth-century Hydraulic Mission reframed water as a technocratic instrument of nation-building, a trend the Islamic Republic intensified. Traditional systems like qanats and collective governance were supplanted by dams, diesel pumps, and centralised planning, producing ‘modern water’—abstracted, decontextualised, and commodified. This ontological shift delivered short-term gains but degraded ecosystems, partly contributing to Lake Urmia’s decline.