Onion Creek
McKinney Falls is the perfect getaway into nature right outside Austin. There are plenty of campsites that are a good distance from the water with everthing you'd expect. Some are pretty crampt so I would make sure to plan ahead and choose which site you want. The water is beautiful and the surrounding area is awesome. Definitely can be a lot of people though on the weekends and on good weather days.
Month of VisitSeptember