Reviews how pond systems work and provides guidelines for their application. An initial overview of the technology and then the science of the pond environment is discussed in detail. This knowledge is then used as a basis to explain the processes and mechanisms that are intrinsic to actually providing the effective treatment of various pollutants. From this scientific grounding the book becomes increasing applied in its approach, firstly providing design guidelines, then reviewing specific applications and variations of the technology and finally concluding with a number of practical case studies.