It is collected by water agencies within each hydrographic basin. The charge builds on a characterisation of water resources as regards availability: Category 1 and Category 2 resources are those situated respectively inside and outside Water Apportionment Areas (ZREs in French, for Zones de Repartition des Eaux), which are zones characterised by a chronic w'ater deficit. The spatial distinction between Category 1 and Category 2 resources reflects the higher opportunity cost in ZREs where there is a serious imbalance between water demand and water availability.