Agriculture is the oldest and most important influence on the hydrographic network of the Po watershed. Already during the Roman age, and then again starting in the late Middle Ages, agriculture drove rivers’ diversions, construction of irrigation canals, and drainage works. After 1860, however the scale of irrigation canal building and drainage works changed, with the construction of new, more ambitious infrastructure which included the regulation of the outflow of the big Alpine lakes. This maps shows the most important of these waterworks. One layer shows irrigation canals built after 1860, with information on years of construction. One layer shows the dams regulating the Alpine lakes. A third layer shows the most important drainage canals built after 1860.