UNEP GEMS/Water Global Freshwater Quality Archive

Large-sample datasets are essential in hydrological science to support modelling studies and global assessments. The present dataset compiles all freshwater quality data that is available under open data policy (CC BY 4.0 or equivalent) in the GEMStat database for global water quality (www.gemstat.org). Additional data under Creative Commons license CC BY-NC 4.0 (or eqivalent) is available for non-commercial use via the GEMStat portal or request to [e-mail]. GEMStat is operated by the GEMS/Water programme of the United Nations Environment Programme (UNEP) and hosted at the International Centre for Water Resources and Global Change (ICWRGC) and the German Federal Institute of Hydrology (BfG). The data in GEMStat is provided by National Hydrological Services of UN Member States. The data available here at Zenodo consists of a zip archive with 80 individual csv files for different parameter groups. Three csv files provide metadata information on stations (GEMStat_station_metadata.csv), parameters (GEMStat_parameter_metadata.csv) and analytical methods (GEMStat_method_metadata.csv). A text file (README_output_format.txt) gives information on the different entry classes in the data files. If you have querries regarding the dataset, please contact the GEMS/Water Data Centre via email to [e-mail]. VERSIONS Version v3 This version includes all data submissions from 2025. It comprises over 50,000,000 measurements on 622 water quality parameters, covering 22,982 stations in 42 countries over the time period from 1906 to 2024. Version v2 An error was corrected that led to overestimation for all parameters in Version v1. Version v2 includes all data submissions until November 2024, with over 20,000,000 measurements on 608 water quality parameters, covering 13,660 stations in 37 countries over the time period from 1906 to 2023. Version v1 To avoid further download of Version v1, access to it has been restricted while Version v2 is publicly available.