From Austin, take HWY 71 west to HWY 281, then north through Marble Falls to Park Road 4 (don't go all the way to Burnet, as Park Road 4 is much more scenic and just as fast).
A funny story: just as I was walking to the edge of the lake to take this picture, a man in his underwear stepped out of a nearby cabin, saw my photographic gear, and quickly stepped back inside. Apparently afraid of a quick candid shot.
This photo was taken just before dawn in late Autumn of 2008. The cool air was creating columns of mist 50' high, and a solitary duck was out for a swim. On the far side of the lake are gorgeous homes situated high in the hillside. The morning light was just beginning to light their facades.