Sefydlwyd Awdurdodau'r Parciau Cenedlaethol o dan ddarpariaeth Deddf yr Amgylchedd 1995. Mae gan Awdurdodau'r Parciau Cenedlaethol ddau ddiben statudol dan Ddeddf yr Amgylchedd 1995:
The National Park Authorities were established under the provision of the Environment Act 1995.  The National Park Authorities have two statutory purposes under the Environment Act 1995:To conserve and enhance the natural beauty, wildlife and cultural heritage of the National Parks.To promote opportunities for the understanding and enjoyment of the special qualities [of the Park] by the public.