Most of the land surrounding the lake is BLM land and open to dispersed camping. We camped at a flat, graveled pull off near the boat ramp. There are a few sites closer to the water but the dirt roads leading to them are not suitable for most RVs and vans so walk the area before driving in.
This is a very good campsite if you want to visit the small town of Blanding.
Lake 37.66744, -109.44365