US Army Corps of Engineers
Pittsburgh District

Locks & Dam 3, Mon River

Aerial view of Locks & Dam 3, Mon RiverP.O. Box 455
Elizabeth, PA 15037-0455
412-384-4532

Locks and Dam 3 is one of nine navigation structures which provide for year-round navigation on the Monongahela River between Pittsburgh, Pa., and Fairmont, W.Va.. It maintains a pool for 23.8 miles above the mouth of the Youghiogheny River, just above Elizabeth, Pa.

Location
Locks and Dam 3 is located at river mile 23.8 at the city of Elizabeth. The lock chambers and operations buildings are situated along the right bank of the river adjacent to a main line of Pittsburgh and Lake Erie Railroad. Road access to the project is from a local road going south out of Elizabeth.

History
Construction of Locks and Dam 3 at this present site was begun in 1905 and completed in 1907. After some 70 years of use, a major rehabilitation of the project, the busiest on the Mon River, was completed in 1980. This work involved reconstruction of the lock chambers.

Project Information
Locks and Dam 3 consists of two lock chambers and a fixed crest dam. This type of dam is basically a concrete weir or wall across the river which keeps the river channel upriver of the project deep enough for navigation -- about 9 feet or more. Water which flows over this type of dam cannot be controlled locally. Consequently, it cannot provide any control over flood waters. An incidental benefit derived from the pool formed by the dam is the availability of a source of municipal and industrial water.

Locks and Dam 3 is part of the Lower Mon Project which has modernized Braddock Locks and Dam, is in the process of modernizing Locks and Dam 4, Charleroi, Pa., and will remove Locks and Dam 3, Elizabeth, Pa.