Under federal legislation (Federal Act of 24 January 1991 on the Protection of Waters/GSchG, SR 814.20), the federal authorities are required to carry out national surveys of the elements of the hydrological balance and of surface and groundwater quality, and to make the results available to interested parties. The Water Division of the Federal Office for the Environment (FOEN) is the federal agency responsible for performing these tasks. This information is necessary to meet the requirements of environmental protection, water management or the planning of public works, but also for purposes of scientific research and public information.