Hydroelectric power plants (HPP) have the ability to store part of the energy and engage in the grid in a very short period of time, thus contributing to the stability of the power system. The flow-through derivative hydroelectric power plant Miljacka has been continuously operating since the moment of commissioning. Built in 1906 on the Krka River basin. Due to the specific location, the entire hydroelectric power plant was built by hand. Until 1910, it was the power plant with the highest installed capacity in Europe. Due to its characteristics, it represents an important energy, industrial and cultural heritage, and in 2018 it was inducted into the Hydro Hall of Fame. The observed Krka River basin has four waterfalls, with a total altitude difference of 106 meters. The total installed capacity of HPP Miljacka is 24 MW, and the available constructive drop of water is 102 meters. Miljacka HPP has introduced and certified the “Environmental, Quality and Energy Management System" in accordance with the standards ISO 14001:2015, 9001:2015 and 50001:2018.