The contribution will examine the exploitation of water resources in the basin of the river Soča and its tributaries after World War I when this territory was annexed to the Kingdom of Italy. In particular, it will focus on the position of small private installations: mills, sawmills, blacksmiths, small hydroelectric power stations, and other mechanical production facilities that used water power for their operation. Most of these had existed already before World War I, but after the formal annexation of this territory to Italy and the entry into force of the Italian legislation on public works and the reconstruction of war-damaged infrastructure, the owners were forced to apply for the right to use public waters. They had to fill in a formal application to prove the existence of a right to use the water source in the past (either by documents or by witnesses’ oaths before a notary), as well as attach detailed technical studies and construction plans, which was extremely expensive, especially for the owners of small businesses. The overwhelming majority of successful applications reveal that the fascist authorities did not hinder private enterprise and saw it as an important step towards self-sufficiency. However, they also took into account the racial, political, and ideological background of the applicant in their decisions and imposed a water levy on the concession holders, which was a novelty and often represented an overwhelming burden for many, who consequently decided to return the concession they had already received. The situation proved to be more complicated only for the owners of the water-powered facilities located within the area of interest of the prominent Italian electricity companies that designed and built large hydroelectric power plants, where the public interest outweighed the rights already granted to private parties. Based on the archival materials providing an overview of 38 ABSTRACTS OF PRESENTATIONS the mostly unpreserved technical heritage, a series of installations will be presented, from the “primitive and pitiful”, as Italian officials described some of them, to the actual electrical companies which used domestic capital to set up plants with a larger capacity. Special attention will be paid to the environmental requirements, such as ensuring a minimum water flow and the measures for the protection of aquatic life and bank protection, which private investors had to comply with