Lock and Dam 50
(Before 1929)
The first Federal improvements for navigation on the Ohio River came in 1824 with the removal of snags and sandbars. These measures were effective, but they were only temporaryŚnew sandbars would appear after every flood. They also provided no relief against low water, which stopped navigation almost every year. The construction of a dam with a stable pool and a lock bypassing the dam would have ended problems caused by low water, but the shippers who needed the full width of the river for maneuvering were opposed to a dam.
A compromise solution was a movable dam that could be raised in times of low water to create a pool and lowered when the flow was adequate for navigation. The dams finally built had a series of Chanoine wickets, invented by Frenchman Jacques Chanoine, extending across the river. A system of 50 movable dams was built on the Ohio River between 1879 and 1929, making the Ohio navigable for its entire length at all times.

Each dam actually consists of a row of 300 or more little dams, individually hinged to a foundation on the river bottom. The wickets are constructed of heavy timber about 4 feet wide and up to 20 feet long. Raising or lowering the wickets is done by a crew on a maneuver boat that moves along the upstream face of the dam. A bar is connected to the back of each wicket with the free end riding in a groove in the foundation. To raise them, a grapple hooks a wicket and pulls it from the bed of the river. The bar slides up the groove to a niche, where it catches and supports the wicket upright against the flow of the river.

The Lock walls at Lock 50 were raised up 2 more feet during it's lifetime. The Lock is flat (even elevation) in this photo and it stayed that way for quite a long time. Sometime later in it's life wickets 2 foot longer than the originals were put in the dam as was raising the lock walls two feet.