Proses yw Asesu'r Effeithiau Amgylcheddol (“EIA”) ar gyfer penderfynu ar brosiectau sy'n debygol o gael effaith arwyddocaol ar yr amgylchedd gan ddefnyddio'r wybodaeth drylwyraf bosib fel bod anghenion yr amgylchedd a rhai cenedlaethau'r dyfodol yn cael y sylw priodol.
Environmental Impact Assessment (“EIA”) is a process which enables decisions to be taken about projects which are likely to have a significant impact on the environment with the fullest possible information and for projects to be designed to mitigate those impacts.