The purpose of the new edition is to introduce the basic concepts of water quality and how it is related to ecosystem and human health; and to present an overview and assessments of current and upcoming global water quality issues with examples from around the world. It also includes a new chapter highlighting how Ecohydrology can serve to help achieve the Millennium Development Goals on water and sanitation. The target audience includes academia, research scientists, and water practitioners, and can serve as a background to water assessments being conducted at regional and global scales.