lake travis is around 35% of capacity. it's not really a lake right now, more like a river winding through canyons of what used to be lake. there are videos on this site (middle of the page) http://www.lcra.org/
just for fun has party boat rentals, or used to. you can pretty much get as crazy as you want and the lake is pretty quiet now with all public ramps high and dry.
lake austin really is a river, below the dam that creates lake travis. great water or boarding but pretty boring for party boats. austin party cruises has pontoon boats but i don't think they get too crazy. never been on one. most of lake austin is lined with homes so you're never far from scrutiny or shore since it's really just a river.