In reply to Chick-on-a-Rope: there has been a lot of rain with the Lligwy in spate.
Plenty of alternative sites in the area.
The farm behind the Bryn Tyrch Pub,camping higher on the hill will be dry and close to amenities.
There is a hillside terraced campsite outside Betws near Swallow Falls.
On the backroad from Betws to Trefriw there is a nice caravan park with an idyllic area set aside for camping,cannot remember name....Cwm something.
A bit further out on the road between Betws and Dolwydyllyn is a real treasure TanAldroch (sic) beautiful wooded quiet site with the Lledr River running through it - never gets loud or yobby and you are allowed to make open fires,only down side itt can get midgy.
Good luck and enjoy your stay,it's a beautiful area.
Also I'm pretty sure we have a Capel Curig website with links to all the accommodation,sorry I. Cannot give you a link.
Apologies for Simon4 he has a bit of a history of sneering superior posts and isn't typical of the folk you can find on UKC