The lake is open to Trout all year, the rivers have a closed season. During the warmer months the Trout tend to go deep so a lot of the locals, I met quite a few when I joined the Jindabyne Fish club, tend to start fishing at the end of the Ski season, mainly because a lot of them are too busy during the season, then take a break over Christmas and into the New Year, then start again mid to late Feb till the start of the Ski season. one of the problems during the really warm months is that there are a lot of boats around water skiing and generally enjoying the water. Apparently the extra noise in the water sends the trout running for cover.
Some of the best fishing is during the colder months. I have been down there with ice and frost covering the boat and -1 or 2 degrees as I launch before sun up. Seen some good fish on those days. 🙂
If you want to talk about how and where message me and I'll give you my phone number so we can talk through your options.