Originating in Marion county, West Virigina and flowing north into Pennsylvania's Greene, Fayette, Washington, Westmoreland and Allegheny counties.
With heavy commerical and industrial traffic, the Monongahela River has six locks and dams. It joins the Allegheny River in Pittsburgh to form the Ohio River.With navigation on the river once being used by only canoes and flatboats, it is now heavily used as a barge route, carrying coal, coke, iron, and steel. To accommodate for the barges, the locks and dams along the river maintain a minimum depth of nine feet.
Once home to 58 of Pittsburgh's steel mills, the properties along the river have since been redeveloped in recent years. However, the first industry to use the major waterway was boat building. Now, the river furnishes hydroelectric power to several cities in its upper reaches and is a source of drinking water for about one million people.