At 240-feet high, Pistyll Rhaeadr is the tallest waterfall in Wales.
A spectacular waterfall near Llanrhaeadr ym Mochnant in mid Wales, has been chosen by the Countryside Council of Wales to join 999 other specially protected natural areas.
A commemorative plaque will be unveiled by CCW Chairman, John Lloyd Jones, to mark the occasion.
At 240-feet high, Pistyll Rhaeadr is the tallest waterfall in Wales.
The falls mark a significant change in the lay of the land from mountains down to a lowland stream.
The falls show spectacular plunge pools and a natural arch, a product of its different rock types and structure.
Above Pistyll Rhaeadr the river is known as Afon Disgynfa and below as Afon Rhaeadr.
George Borrow - 19th Century traveller and author of Wild Wales - was impressed by the falls.
" I never saw water falling so gracefully, so much like thin, beautiful threads as here," he remarked.
Natural beauty
The best time to visit the falls is in spring, when the melting snows from the 2,700 foot high Moel Sych feed the mountain streams.
Although SSSIs are guaranteed a measure of protection, the CCW hopes that changes to the Countryside and Rights of Way Bill will strengthen their status and maintain their natural beauty.
"This is the best example of such a feature in Wales with a dramatic waterfall and change in river processes," said Earth Science officer Raymond Roberts.
"I think it is important to make everybody aware of its importance."
All of the sites in Wales are managed by landowners and conservationists so that future generations can enjoy these pieces of Welsh heritage for years to come.
The site will continue to be managed by the present landowners, the Wynnstay Estate.