The Allegheny River rises from a spring in Potter County in north central Pennsylvania, one hundred thirty miles upstream of the Kinzua Dam, then flows northwest into New York and southwest back into Pennsylvania. The Iroquois and Shawnee who lived along the river called it "O Hi Yo," and the Iroquois of western Pennsylvania considered the Allegheny the upper part of the Ohio River, with Iroquois Ohio meaning "beautiful river." After the Delaware, an Algonquin people, moved into western Pennsylvania in the eighteenth century and displaced the Iroquois, they translated Iroquoian Ohio into Delaware as welhik-heny, meaning "most beautiful stream," and that name was later anglicized as Allegheny. Construction of Kinzua Dam, the river's only flood control project, was completed by the U.S. Army Corps of Engineers in 1965, creating a twenty-four-mile reservoir; the dam is eight miles upstream of Warren, Pennsylvania, and one hundred ninety-five miles upstream of Pittsburgh, Pennsylvania. Downstream of the dam, the Allegheny, designated a Wild and Scenic River, follows a broad zigzag course southward across western Pennsylvania past Warren, Tidioute, Tionesta, Oil City, and Franklin. Before railroads, the river was important for transporting coal and lumber, and it now serves recreation and continues to provide valuable wildlife habitat. From its spring in Potter County to Point State Park in Pittsburgh, the river runs three hundred twenty-five miles, where it joins the Monongahela River to form the Ohio River, and its water ultimately reaches the Gulf of Mexico by way of the Ohio and Mississippi rivers. A watershed is an area of land across or under which water flows on its way to a stream, river, or lake, linking land, water, and living organisms, including people, within its boundaries, so impacts on water quality at Big Bend also affect the Ohio River and Mississippi River watersheds.