Mill Run Recreation Area sits on a side cove of Youghiogheny River Lake in Garrett County, Maryland, a few miles north of Friendsville and just south of the Mason-Dixon line. The cove is the drowned mouth of Mill Run, a small mountain stream that used to join the Youghiogheny here and now runs straight into flat water. The Army Corps of Engineers Pittsburgh District owns and operates the whole reservoir, and Mill Run is one of its developed access points: a swimming beach, a boat ramp, a playground and a 30 site campground, all clustered at the end of one road.

Swimming is sanctioned here. The Corps lists it among the official activities at the site and there is a marked beach. There is no lifeguard and nobody watching the water, so everything that happens in it is on you.

The water is reservoir water, not spring water. Youghiogheny River Lake covers about 2,800 acres, runs 16 miles from the dam at Confluence back up into Maryland, and has 38 miles of shoreline. Average depth is around 54 feet with a maximum near 121 feet, so the main body is cold and dark well before you get far out. The cove at Mill Run is shallower and warmer, and it comes up to temperature fastest in July and August. Visibility is moderate. This is a working flood control reservoir, which matters more than the numbers do: every autumn the Corps draws the pool down hard for winter storage, and the beach ends up well above a shrunken lake with a wide band of mud and old stumps in between. The swimming season is effectively Memorial Day through Labor Day, and the campground itself typically opens around the first of May and closes in September.

Getting there means leaving the interstate behind. From US 40, turn onto Friendsville Addison Road and follow it roughly three miles, then turn onto Mill Run Road and stay on it until it ends at the campground. The last stretch is narrow and rural. Parking is the campground and boat ramp lot, which is adequate on an ordinary weekday and tight on a summer Saturday, because the ramp stays busy. Youghiogheny River Lake is a powerboat and water ski lake, one of the better ones in the region, and the ramp traffic reflects that. Keep well inside the swimming area and stay visible.

Fees are set by the Corps of Engineers. Camping is $20 a night, booked through Recreation.gov or by calling (877) 444-6777, with a 14 night limit and a maximum of two tents per site. The campground number is (814) 395-3242. The Corps does not publish a separate day use charge for the beach, so call ahead if that matters to your plans. Alcohol is prohibited across the site.

The setting is northern hardwood forest on steep slopes, beech and sugar maple and white ash and yellow poplar and basswood, with deer, turkey and grouse around. There are flush toilets, drinking water and a dump station. Friendsville, ten minutes south, is the take-out town for the Upper Youghiogheny, one of the hardest commercially run whitewater stretches in the East, so on a release day the town fills up with rafts and gear.