The degradation of quantity and quality of lake waters nowadays forces scientists to develop advanced methods of studying and understanding lake ecosystems. These methods lead to models that have as an aim to describe in detail the chemical and biological processes that take place in the lake environment. The developed models are then used as tools to predict the exact mechanisms that follow accidents or permanent situations that have as result the degradation of the water quality of the lake. The present paper describes a working frame to develop models for lake management, lists the main variables to be considered and presents their interactions and influences on the lake ecosystem.