In November 1925, the Greek State established the Hellenic Water Company S.A. whose main duty was the construction and exploitation of water supply projects in Athens, Piraeus, and environs. Until then, the Municipality of Athens was in charge of the city’s water distribution. The pioneering program of management and conducting a project that Ulen bequeathed to the Hellenic Water Company S.A. forged a tradition that today is part of EYDAP, the largest company of its kind in Greece. The inauguration of this course is marked by the construction of the Marathon Dam and the creation of the water supply system of the city of Athens.