The Global Environment Monitoring System (GEMS) is a multi-faceted water science center created by the United Nations Environment Programme. GEMS' goals are to improve global water quality monitoring and assessment abilities and to determine the status and trends of regional and global water quality. GEMStat is a global water quality database designed to provide access to surface and groundwater quality data and statistics collected by GEMS.
GEMStat provides two online services for accessing its data: the Web Feature Service and the Web Map Service. The Web Feature Service returns information on GEMS stations and the measurements they've taken. The Web Map Service provides maps of GEMS station locations. Both of these services are accessible programmatically using either SOAP or REST calls.