SupRookie - yes that is correct is is the one on the left near the boat ramp to the river. It has a big Watersports Complex on the edge of it.
There are permanent rowing lanes in there, however the Watersports Complex said that the lake is open to anyone's use, just no motorised watercraft are allowed in there except for model boats.
The only time motorised craft are allowed in there is if there is a rowing regatta. Council has advised that the Nippers are also using it for paddle boarding training - not sure when that is.
I went to investigate on the weekend as I saw the weekend prior that there was some sort of triathlon / swimming going on in there and wondered what it was.
If you are keen to go check it out, happy to meet you there and we can go together - safety in numbers - lol

Otherwise I plan to have a look at the Hinze Dam on the weekend.