An information analysis system (IAS) is being developed to assess the state and predict the dynamics of a lake-catchment system. Forecasting of the state of the lake ecosystem in the context of global climate change and active exploitation of its resources (water,
energy, recreational and biological resources, transport) is done using a three-dimensional mathematical model of the lake ecosystem, coupled with a model of runoff from the catchment. Lake and catchment models are combined with a database and a knowledge base to form a single IAS. The prognostic assessments of the seasonal and long-term dynamics of the lake ecosystem performed using the IAS serve as the basis for identifying the possible economic, social and cultural consequences of regional and global changes. Operational IAS is necessary to create a management decision support system.