hey mate,
I fished the lake since i was a kid and one thing i've learn't is you don't bother fishing there in june, july and most of august you might get the odd good fish but its a hard slog. I always wait for the first few warmer days in late august to september to get back into the flatties there.
If your landbased you better of to go try down around forty baskets, north harbour area where you should get some nice trevally, winter flatties was down there on saturday and got a few trevs on softies and a 50cm flattie.
If you are gunna fish lake i would try the shallows on a nice sunny winters day as they should be up there trying to warm up thats my guess anyways.