A study of the historic-rural landscape and fluvial evnvironment of the Basilicata (southern Italy) has been carried out by analysis and intepretation of the cartographic, bibliographic and archive sources. Water-mills data have been organized in a GIS database, thanks to the study of a lot of ancient and modern cartographies. Different water-mills, which were very important for the rural economy, until the 20th century, were powered by water to grinding grain and to fulling wool fibres (waulking mills). Most watermills were usually placed along the slope of V-shaped valley, far away from the main roads, but at the same time, they entailed a change to in the local river dynamics due to the deviation of the watercourse. Among all the cartographies considered, in this paper we discuss about the Hydrographic Map of the Italian Kingdom, published in 1890s, the most complete, “recent” and not much studied document about watermills. All the data, that are collected in a relation associated to the Hydrographic Map of the Italian Kingdom, have been discussed, enphasizing errors to be taken into account.