For millennia, Egyptian rulers dedicated vast resources to managing the annual inundation of the Nile, with the mandate to govern Egypt contingent upon the critical responsibility of channelling and gauging the river. These responsibilities encompassed critical administrative, engineering and hydraulic undertakings, from dam construction and canal dredging to precise monitoring of water levels to predict harvests and levy taxes. Yet, this mandate was also contingent upon the veneration of the Nile as both guarantor of Egypt’s prosperity and the conduit of divine grace and God’s agent of reward and punishment. Nile veneration in medieval Islam addressed these symbolic and spiritual aspects, through ceremonies enacted throughout the year centred on the nilometer (al-miqyās) at the island of al-Rawda, which served as supplications to God for a precise level of rising flood waters. Striking a delicate balance between the pragmatic and symbolic necessitated a nuanced response to the ancient practice of Nile veneration, one which had no precedent in Islam. My intention is to examine the interplay and balance between these considerations by analysing the phenomenon of nilometer construction in medieval Islamic Egypt through the lens of Nile veneration between the 7th and 11th centuries CE.