This article presents a study of the hydraulic structures -known as dams- in the Jimbe River sub-basin of the headwaters of the Nepena Valley (Ancash), based on systematic surveys carried out in that sector. This study allowed for recording 14 pre-Hispanic dams in three different sub-valleys. The morphological and spatial analysis of these hydraulic systems suggests differentiated management of water on the western side of the Cordillera Negra and provides evidence for a reassessment of land use strategies set up by Sierra people during the late pre-Hispanic Period.