Images of Lock and Dam 24, Mississippi River Mile 243.4, Clarksville, MO

“The Mississippi is well worth reading about.

It is not a commonplace river, but on the contrary is in all ways remarkable.”

Mark Twain,

Life on the Mississippi, 1863

Lock and Dam 24 is located at Mississippi River Mile 273.4, 93.5 miles upstream of St. Louis, at Clarksville, Missouri. Construction of Lock and Dam started in July 1936, and the lock was put into operation on May 12, 1940. It was the first dam on the Upper Mississippi River that was without roller gates, but instead applying Tainter gate technology. Normal pool elevation behind the dam is 449 feet. The movable portion of the dam is 1,340 feet long and consists of 15 fully submersible 25 feet high by 80 feet long Tainter gates. A 2,720 feet submersible earthen dike extends from the movable dam to the Illinois shore. Its 13,000-acre pool is 27.8 miles long. Lock dimensions are the standard 110 by 600 feet, with the upper gate bay section of an auxiliary lock. Average lift is 15 feet.

In 2004, the facility was listed in the National Register of Historic Places as Lock and Dam No. 24 Historic District, #04000183.

Lock and Dam 24 is founded on durable shale, unlike Locks 25 and Old Locks 26, which are pile-founded structures built atop sand and gravel. Because of the presence of a firm foundation material, the lock chamber is not floored and no lateral struts were provided to stabilize the intermediate and river walls.

The Tainter gates are raised and lowered by individual electric motors, connected by line shafting to link-chain hoists, located beneath the dam service bridge. The piers provide support for the Tainter gates and the steel deck girder service bridge that extends the length of the dam. The submersible, elliptical Tainter gates of Dam 24 represent the apex of gate design achieved during the project. At the time of their construction, the U.S. Corps of Engineers believed these gates to be the largest Tainter gates ever constructed. Because of the large size of the Tainter gates, and the relatively ice-free conditions of this stretch of river, roller gates were eliminated entirely from the dam design. These Tainter gates were innovative that they rendered roller gate technology, the principle engineering feature in dam construction at the time, obsolete.

[The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow; a side view of a Tainter gate resembles a slice of pie with the curved part of the piece facing the source or upper pool of water and the tip pointing toward the destination or lower pool. The curved face or skinplate of the gate takes the form of a wedge section of cylinder.]

Lock and Dam 24 was the first dam on the ambitious 9-Foot Channel Project that constructed without roller gates. The Upper Mississippi River 9-Foot Navigation Project, authorized by River and Harbor Acts of the 1930s, is a series of 29 locks and dams on the Upper Mississippi River (UMR) to create a 9-foot deep navigation channel, completed by 1940, critical to national shipping and commercial interests. While the project vastly improved the means for shipping grain from the upper Midwest to New Orleans, it also fundamentally altered the river’s hydrology and ecosystems. The 9-foot channel system consists of a series of dams and navigation pools along the river. The deep water in these pools enhances navigation, but the pools also have submerged backwater areas and have disrupted the natural, seasonal ebb and flow of waters that help sustain the diversity of plant and animal life along the river.

A major rehab of Lock and Dam 24 was completed in 2005. This work consisted of replacing a large portion of the concrete in the lock chamber walls, walkways and work areas. Also, new gate and valve machinery was installed elevating the electrical components above the 1993 flood levels.

Lock and Dam 24: Pass-through trading Volume (in tons)

lock and dam creates an open ice-free area of water and the churning water stuns the fish making them easy prey for the eagles. Lock and Dam No. 24 is what makes Clarksville famous among Bald Eagle fans. The Lock and Dam #24 is listed on the National Audubon Society's Great River Birding Trail. They report that a viewing platform at the dam provides views of Bald Eagles (mid-November through March), Ospreys, and several species of gulls and terns during spring and fall migration.