Irkutsk Hpp: Regulation of Lake Baikal Water Level Within Environmental and Socio-Economic Contexts

Even after 65 years since Irkutsk hydropower plant (HPP) began operation, the regulation of Lake Baikal water level remains a crucial issue. This matter is important not only for protecting a unique natural object and its ecosystem, but also for considering the interests of adjacent subjects of the Russian Federation, numerous water consumers and water users. This issue has become especially evident in the last decade, with the onset of the extremely low-water period of 2014–2017 and the subsequent high-water period of 2020–2023, which required amendments to the legislative framework for regulating the level of the lake. This situation generated the need to conduct a comprehensive study in 2021–2023, which made it possible to formulate scientifically grounded and practically implementable principles for regulating the level of Lake Baikal under different water conditions, considering modern environmental, socio-economic, and water management requirements and constraints. The study involved the collaboration among the institutes of the Siberian Branch of the Russian Academy of Sciences, the Ministry of Science and Higher Education of the Russian Federation, Roshydromet, and Rosrybolovstvo. The paper presents an analysis of the current legislation on the management of water resources of Lake Baikal. The findings reveal that the permissible meter range of lake level regulation, as stipulated by the Decree of the Government of the Russian Federation, can only be achieved in years with average or near-average water content. In high-water and low-water years, maintaining this range and permissible maximum water levels is impossible. This study used model calculations to identify the optimal and permissible (critical) variations in levels and flow rates of the Irkutsk HPP, as well as to establish the regulation ranges for Lake Baikal for varying water conditions. A procedure for regulating the water levels of Lake Baikal is proposed using the developed reservoir operating curve of the Irkutsk HPP. This approach takes into account environmental requirements and socio-economic constraints.