Scientists, regulators, and the general public are now more and more aware of the chemicals present in surface waters worldwide. Agrochemicals, such as herbicides or insecticides, pharmaceuticals and cosmetics can be detected at low to medium concentrations in seas, groundwaters and rivers. Among freshwaters, lakes are of particular concern. These large reservoirs are used as sources of food and drinking water, but also serve for recreational activities. This book aims in presenting insights into the physical, chemical, and ecological dynamics of mid-sized lakes that enable proposing recommendations for sustainable lake management regarding chemicals. Lake Geneva, Switzerland, is used as a case study, but the developed methodologies and tools can be useful for lake water quality management in general.