Point Marion Lock and Dam, previously known as Lock and Dam Number 8, is one of nine navigational structures on the Monongahela River

Monongahela River

The Monongahela River is a river on the Allegheny Plateau in north-central West Virginia and southwestern Pennsylvania in the United States...

 between Pittsburgh

Pittsburgh, Pennsylvania

Pittsburgh is the second-largest city in the US Commonwealth of Pennsylvania and the county seat of Allegheny County. Regionally, it anchors the largest urban area of Appalachia and the Ohio River Valley, and nationally, it is the 22nd-largest urban area in the United States...

, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 and Fairmont

Fairmont, West Virginia

Fairmont is a city in Marion County, West Virginia, United States. Nicknamed "The Friendly City". The population was 18,704 at the 2010 census...

, West Virginia

West Virginia

West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

. Maintained and built by the U.S. Army Corps of Engineers, the gated dam forms an upstream pool that is 11.2 miles (18 km) long, stretching to the base of the Morgantown Lock and Dam

Morgantown Lock and Dam

Morgantown Lock and Dam is a navigational lock and gated dam on the Monongahela River at Morgantown, West Virginia. It is part of a series of dams that canalizes the Monongahela to a depth of at least for its entire length from Fairmont, West Virginia to Pittsburgh, Pennsylvania. It is...

. It is located at river mile

River mile

In the United States, a River mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the River kilometer...

90.5 (river kilometer 145.6).

There is one lock chamber on the left descending bank of the river at the dam, 84 feet (25.6 m) wide and 720 feet (219.5 m) long. The reservoir formed by the dam is also a municipal and industrial water supply.