Lock and Dam 50
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.
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.