The Water Framework Directive (WFD) required Northern Ireland to define both surface and groundwaters as a coherent set of hydrological units.  These units would then be monitored and managed to prevent deterioration in water quality and aquatic ecosystems through the implementation a programme of measures to drive improvements.  This map displays Northern Ireland lakes which are greater than 50ha, which are assessed under WFD legislation and have been reported to EU from 2016.