Synopsis With continued economic growth, Population increase, urbanization and technical development, more and more waste materials were discharged into natural sources of water, like rivers, lakes, ocean, etc. During the decade extensive efforts were made in the developed countries to assert this pollutions by treating the growing volume of waste discharge. Rivers have always been the dumping ground for man’s unwanted waste material. It is astonishing how much waste cab be actually converted into harmless products by bacteria, but there are limits beyond which rivers cab degenerate into stinking sewers. Nearly all aquatic life depends on he oxygen dissolved in the water and if too much organic matter is present in water the bacteria causing its decay will use up all the oxygen and other organisms will suffocate. It is then that anaerobic bacteria take over and release foul smelling gases such as hydrogen sulphide. But what is being done about it? The book provides a vivid description of its control by many ways. This book will be found of immense use to all environmentalists and all those engaged in research of environment and ecology.