This book is a research effort on the water quality and zooplankton composition, abundance and diversity of a river that receives municipal wastewater in Southern Nigeria. The layout of this book provided a step by step approach to carrying out research in water quality and zooplankton studies. The design of the research, methodology, results, presentation of results and interpretation and conclusion makes this book a companion of students, Animal and Environmental Biologists, Hydrobiologists and Environmentalists as well policy makers in waste management industry.