This site is on the Des Moines River just downstream of the Saylorville Dam. Indeed, the dam looms just a few yards away and one loop is next to the outflow. The facilities are high quality and the site seemed to attract a good group of campers. You will also see locals who come to fish in the river. How can you beat the price?
http://www.reserveamerica.com/camping/bob-shetler-recreation-area/r/campgroundDetails.do?contractCode=NRSO&parkId=73093
We pulled in around 10 pm. Office closes at 9 so we called ahead. Very nice staff gave us directions. There are 3 loops, we stayed in the first loop in a pull thru site by the river. Had a picnic table, fire ring, level white gravel site and 20 or 30 amp power hook up for $18. Hiking trail, dam, fishing, beach up the road and super nice scenery. Bath house was super clean, 2 showers.