The Allegheny River Lock and Dam No. 4 in Harrison Township, Allegheny County, Pennsylvania, is a lock that was built 1920-1927, and opened in 1927, 24.2 miles upstream from the mouth of the river in Pittsburgh. The lock and dam were built by the U.S. Army Corps of Engineers as a part of an extensive system of locks and dams to improve navigation along the

Allegheny River The Allegheny River ( ) is a long headwater stream of the Ohio River in western Pennsylvania and New York (state), New York. The Allegheny River runs from its headwaters just below the middle of Pennsylvania's northern border northwesterly into ...

. It is located about 24.2 Miles up the

from the Point in Downtown Pittsburgh. Also, it is about 6 Miles down the Allegheny from the mouth of the Kiskiminetas River.https://www.lrp.usace.army.mil/Portals/72/docs/navigation/AlleghenyRiverNavigationChart.pdf Upriver, Allegheny Pool No. 4 has an average water elevation of 745.4 feet above sea level and extends about 6.2 miles upriver to Allegheny River Lock and Dam No. 5. Downriver, Allegheny Pool No. 3 has an average water elevation of 734.5 feet above sea level and extends about 9.7 miles downriver to Allegheny River Lock and Dam No. 3. Thus Lock No. 4 lifts and lowers boats about 10.9 feet between the pools. It has a single lock and a fixed-crest dam, keeping the river depth at least 9 feet in the pool above the dam. The amount of water that flows over the dam is not controlled locally, so it does not provide flood control, but it does help provide water to municipalities. Traffic through the lock was about 1.8 million tons in 1998, including shipments of coal, petroleum, sand and gravel, ore, steel, chemicals, fertilizer, salt, flour, lime, and slag. It was listed on the National Register of Historic Places on April 21, 2000.

References

{{Clear Dams on the Allegheny River Dams in Pennsylvania Buildings and structures in Allegheny County, Pennsylvania Dams on the National Register of Historic Places in Pennsylvania Locks on the National Register of Historic Places in Pennsylvania Dams completed in 1927 Transport infrastructure completed in 1927 Moderne architecture in Pennsylvania 1927 establishments in Pennsylvania National Register of Historic Places in Allegheny County, Pennsylvania Transportation buildings and structures in Allegheny County, Pennsylvania