are holding a scientific-technical conference devoted to problems of increasing the operating effectiveness of hydroelectric stations. At the conference there is to be an exchange of experience and mutual information on improving the operation of hydroelectric stations, developing recommendations on the further increase of the effectiveness of water resources use, reliability of hydropower equipment and hydraulic structures, effectiveness of using hydroelectric stations in power systems, introducing progressive methods and means of operation and maintenance, increasing labor productivity, and decreasing operation costs. The high effectiveness of the hydroelectric station operation is characterized, for example, by the fact that during the years of the Ninth Five-Year Plan 250 million tons of reference fuel (i.e., fuel with a calorific value of 7000 cal/kg) was saved as a result of the output of hydroelectric stations; about 60-70 million man-hours of operating personnel labor are saved annually at hydroelectric stations. The development of hydropower resources simultaneously fosters the development of many branches of the national economy (irrigation, water supply, transport, fishery, etcJ. Taking into consideration the importance of the conference being held for the development of hydropower engineering and increasing the operating effectiveness of hydroelectric stations and pumped-storage plants, the editor of the journal "Gidrotekhnicheskoe Stroitel'stvo" is publ~hing in this issue a series of articles devoted to these problems and invites specialists to submit their articles and comments for the purpose of exchanging experience in the operation of hydroelectric stations.