how to get to High Falls

Since i'm only a part-timer, would some one tell me how to park near High Falls? Last year, when I reached near the end of my canoe trip, I noticed there was a little sandbar right before you get to the high falls and people had lawn chairs sitting over the rapids. I guess that's somewhere near Rio Vista--i dont know. Anyway, looks like its going to be another hot weekend, and that lawn chair idea looks like a good one. Any ideas of where to park and how to get there?