Good question. I know that I had the same question before my first trip down there. It will be at the State Park, which is on the southern side of the lake. You will turn onto Hwy 293 (only 1 way to turn) off of Hwy 425. You will make a left hand turn about 5mi down. There are signs marking both turns.

Once you turn into the state park, the first right will take you into the campground. The second right will take you to the boat ramp.