We used to fish the dam quite a lot a few years ago but lost interest because of the effort to catch rate. Our main success came with barbel on worms.
The difficulty is you need to fish right down at the dam wall and paddle baits out to the middle of the dam almost in line with the chimney.
We only ever landed one good carp there of about 8kg on a barbel bait. I think most of the carp have been taken out because we have tried every spot on the dam with almost every bait including some overnight sessions that resulted in nothing but some extremely cold bodies
