Hey Fin-nor, my father-n-law lives at Waihi beach. If your up the northern end by the hot pipi cafe, go and bang on the door off the deck of the 2 story blue house and ask for Brian, hes always looking for an excuse to get out for a flick.
If you looking for some spots to try he should be able to help or try by the stream that runs out bout 5 k's down the beach there is normally some nice water round there you just have to have a look for it. Hope this helps and good luck with your fishing.