The chemical groundwater state is more critical. Parts of the groundwater are at risk in almost the entire Rhine watershed. Locally, groundwater may be polluted by historic pollutions or accidents with substances hazardous to water. Exhaustive pollution, particularly with nitrate and plant protection agents from agricultural surfaces is considerably more problematic. Agricultural applications must be further optimised with a view to avoiding or at least reducing nitrate leaching. This also applies to the use of plant protection agents.