The Youghiogheny River, known as the Yough (pronounced Yawk), flows from Maryland and West Virginia to the Monongahela River at McKeesport, south of Pittsburgh. The river takes an unusual U-turn around Ferncliff Peninsula. The southern section of the Yough in Pennsylvania flows 39 miles –11 miles in Youghiogheny River Lake, an Army Corps of Engineers flood control impoundment — and 28 miles that flow free through Ohiopyle to South Connellsville, where a hazardous dam must be avoided. This section has historically been divided into the Middle Yough with Class I and II water that drops 11 feet per mile, and the Lower Yough, famous for Class III and IV whitewater with an average gradient of 25 feet per mile. The northern Yough remains largely undeveloped for 46 miles, falling a more modest 5.5 feet per mile from Connellsville to West Newton and a mere 1 foot per mile as it approaches the Monongahela, which flows to the Ohio and Mississippi Rivers and the Gulf of Mexico. The entire water trail is rarely too low to navigate because of releases from Yough Dam.