Two clubs share the canalised Waterton stretch - The Pencoed and The Ogmore AA. The latter has a waiting list see web site (
http://www.ogmoreanglingassociation.com/) but I do not know about the former has a lot of water up stream, speak to Richard Tomlinson - very helpful - on 01656 863699.
I think wading is Ok but it is restricted in spawning seasons (for both trout and grayling) - the rules specify when.
My son fished it quite a lot (and hoping to go down in next few weeks) - serious numbers of grayling, good sized too.
Tight lines!
Mark