Since the late 19th century, hydropower has developed as a clean, safe, reliable and inexpensive source of power and energy service. Hydropower generation corresponds to about 12% of the European net electricity generation and 36% of electricity from renewable resources in Europe (EUROSTAT, 2019). Hydropower is technically mature and is usually economically competitive under liberalized market conditions. It also provides significant benefits to the whole power system; in fact, the fast response capabilities provided by reservoirs and pumped storage plants provide critical energy to electricity networks, helping to match fluctuations in electricity demand and supply from intermittent and less flexible electricity sources.