1. An increase in the operating efficiency of hydroelectric plants attained by the development and use of additional resources requires the complex examination of a broad range of questions concerning their operating conditions and schedule. 2. For each hydroelectric plant it is necessary to examine all possible means of increasing the efficiency for the entire system of structures and equipment, forcusing attention at hydroelectric plants in mountainous regions on such problems as decreasing seepage losses from the reservoir and intake diversion systems, decreasing head loss and increasing the potential capacity of water-supply conduits and structures, consideration of the variation in the performance curves of units with time, asymmetry of the water supply to turbines in problems dealing with optimum scheduling of power plants operation, particularly for short-term regulation, etc. 3. A distinct power effect may require both optimization of the short-term operating conditions of networks of hydroelectric plants with consideration given to the nonsteady state of the head- and tailwater of the hydraulic facilities and optimum load distribution between electric power plants within the system. 4. The methods for increasing the operating efficiency of hydroelectric plants situated in mountainous regions, which are cited in the present study, can be used at a other hydroelectric plants for similar undertakings under compatible conditions.