<a href="https://en.wikipedia.org/wiki/Dredging" class="extiw" title="w:Dredging">Dredging</a> below <a rel="nofollow" class="external text" href="https://www.lrl.usace.army.mil/Missions/Civil-Works/Navigation/Locks-and-Dams/McAlpine-Locks-and-Dam/">McAlpine Locks</a>.
<p>Bow of <a href="https://en.wikipedia.org/wiki/Dredging#Cutter-suction" class="extiw" title="w:Dredging">cutterhead dredge</a> "Bill Holman".
Crewman using a sounding pole to measure water depth.
</p><p>Fast-moving water carries more <a href="https://en.wikipedia.org/wiki/sediment" class="extiw" title="w:sediment">sediment</a> than slow-moving or still water, so rivers pick up sediment during high-flow periods (such as floods) and deposit it when and where the flow rate decreases.
One place on the Ohio River where sediment is deposited is just downstream from the McAlpine Locks.
The navigation channel below the locks is dredged almost every summer to maintain a minimum depth of 9 feet.
Mud (along with with some rocks and other objects) is sucked up from the riverbed, pumped through a pontoon-supported pipeline (similar in some ways to a <a href="https://en.wikipedia.org/wiki/pontoon_bridge" class="extiw" title="w:pontoon bridge">pontoon bridge</a>), and discharged downstream, outside of the navigation channel.
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This dredge is owned by <a rel="nofollow" class="external text" href="http://www.luhr.com/">Luhr Bros.</a>, contractor for the <a rel="nofollow" class="external text" href="https://www.usace.army.mil/">U.S. Army Corps of Engineers</a>, which is responsible for maintaining a navigable depth of 9 feet on the river .
(The Coast Guard maintains aids to navigation such as buoys, lights and daymarks).
</p><p>See a <a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=MsPbGXwad0w">video about cutterhead dredges</a> from the European dredging company <a rel="nofollow" class="external text" href="https://www.jandenul.com/en/equipment/fleet/cutter-suction-dredger">Jan De Nul Group</a>
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<a href="https://en.wikipedia.org/wiki/Ohio_River" class="extiw" title="w:Ohio River">Ohio River</a> mile 607.
<a href="https://en.wikipedia.org/wiki/Louisville,_Kentucky" class="extiw" title="w:Louisville, Kentucky">Louisville, Kentucky</a>.
July 24, 2002.
file # a2g066b.
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IMG_0255.
</p>
Canon PowerShot A40 digital camera.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/70020260@N04">William Alden</a> from Louisville, Kentucky, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/bill_alden/43061577552/">a2g066b: Bill Holman dredging below McAlpine Locks, Louisville</a>