The data and analyses presented in Water Quality for Ecosystem and Human Health are from GEMStat, the global water quality database created by UNEP’s GEMS/Water Programme, the only programme in the UN system exclusively dedicated to monitoring and assessing environmental water quality. Drawing on examples from around the world, Water Quality for Ecosystem and Human Health presents assessments of current water quality status and trends. It also provides an introduction to a diverse range of global water quality issues, including approaches to their identification, analysis and resolution.