The course material concerns basic principles of restoration techniques of various important aquatic ecosystems and will have the following structure: 1. Why restoration of aquatic ecosystems? 2. What is ecological engineering? 3. Basic functions of ecosystems 4. Eutrophication 5. Lakes as typical examples 6. Assessment of problems 7. Dilution techniques 8. Artificial ventilation 9. Inactivation of pollutants 10. Sediment removal 11. Artificial mixing 12. Case studies