The present work intends to provide new data on the hydraulic devices of the Islamic West, thus directing attention towards the fluvial waterwheels. For this, first of all, an attempt has been made to analyze the varied terminology used by historical sources for this type of structures in order to distinguish its nuances. However, after this first linguistic approach, the interest has been focused on a group of waterwheels located in Fez and whose remains have never been subject of an exhaustive survey. In this way, given the material value of some norias and the possibility of relating them to news provided by the Marinid chronicles, we present a study and interpretation that has been possible thanks to a previous planimetric documentation.