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The McAlpine Locks and Dam is located on the Ohio River 604.5 miles downstream from Pittsburgh, Pennsylvania, at the northwestern end of Louisville, Kentucky, in the section known as Portland. The navigation locks are located on the Kentucky side of the river at mile 606.8. The upper pool extends approximately 75 miles to the Markland Locks and Dam.


The project was approved by the Secretary of Army on November 8, 1955, under authority of Section 6 of the Rivers and Harbors Act approved March 3, 1909.


The Falls of the Ohio are located at Louisville, Kentucky, and are the only falls in the entire length of the Ohio River. They consist of a rock reef extending across the river and forming a rapids having a length of about 3 miles. The low water slope in this distance is 26 feet and the falls or rapids in their natural state were impassable by vessels except at high stages.

As early as the year 1802, the expense and delay attending the reshipment of freight around the falls had become so serious that numerous plans were proposed for overcoming the obstruction. No active measures were taken until the year 1825, when the Louisville and Portland Canal Company obtained a charter from the legislature of the Commonwealth of Kentucky. This charter authorized the company to construct a canal around the Falls of the Ohio within the State of Kentucky.

The canal was completed and the first boat passed through December 22, 1830. As originally constructed, the canal was 1.9 miles long, 64 feet wide, and had at its lower end a 3-flight lock with a total lift of 26 feet. Each chamber was 198 feet long between miter posts, with available length of 185 feet, a width of 50 feet, and a lift of 8 2/3 feet. The canal had a depth of 3 feet at low water stage. At the time the canal was completed, its dimensions were thought to be sufficient for all time, but by 1852 only 57 percent of the craft in use on the western waters could pass through the locks. In June 1874, the War Department, Corps of Engineers, assisted the supervision of navigation. In 1880, navigation was made free of any traffic charge. Various improvements and alterations were made until they culminated in a combined navigation and hydroelectric development. This development was completed in 1930, and formed an integral part of the canalization of the Ohio River by the United States.

The lock numbering system was established about 1914 and the Louisville and Portland Canal became Locks and Dam 41. On May 24, 1960, the name was changed officially to McAlpine Locks and Dam in honor of W.H. McAlpine, former Louisville District Engineer, during the years 1917-1918. He was the only civilian employee of this district to hold this position since the Louisville District was established in 1886.

Falls Of The Ohio National Wildlife Conservation Area

PL 97-137, passed by the U.S. Congress in 1982, designated the fossil beds and falls area as "The Falls of the Ohio National Wildlife Conservation Area." Responsibility for operation and management has been vested in the Louisville District.

McAlpine Locks & Dam
Dam Information
TypeConcrete Fixed Weir with Tainter Gates
Length8,627 feet
Upper Pool420 feet
Lower Pool383 feet
Number of Gates9
Height of Gates22 feet
Width of Gates100 feet
Lock Information
Main Lock110 x 1200
Auxilliary Lock110 x 600
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