Walking distance? Yes. It's doable, but maybe not enjoyable. Your best bet is a pedicab. After a few days of the fest you probably won't want to do the walk. Last year I tipped a pedicab guy $40 because it was so great not to have to walk anymore. The 1L bus is the express and will take you from Congress/Barton Springs to 6th and Congress. Then it's a quick walk up to Red River. A bike would also work, but I'm not sure where you would be able to securely lock it up.