The Captain Anthony Meldahl Locks and Dam is a non-navigable river control dam with an associated lock

Lock (water transport)

A lock is a device for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is...

, located at mile marker 436 on the Ohio River. The dam has a top length of 1756 feet (535.2 m) with a 372 feet (113.4 m) fixed weir

Weir

A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...

and a 310 feet (94.5 m) open crest. At normal pool elevation the length is 95 miles (152.9 km) upstream encompassing an area of 21700 acres (87.8 km²).