View downstream from the Tonoloway Creek Aqueduct towards Lock 52 on the Chesapeake and Ohio Canal

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Lock 52 and the Tonoloway Creek Aqueduct are located in Hancock, Maryland, at Mile 122.9 on the Chesapeake and Ohio Canal towpath. They are within a short walk from the parking lot at the Bowles House (former Hancock Visitor Center). See the Locks and Lockhouses web page for an interactive location map.

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A canal aqueduct is a nifty little feat of engineering that solves the problem of what to do when a canal crosses paths with a creek or river. Both are waterways, but the canal is a self-contained channel and cannot temporarily merge with the river because all of its water will spill out uncontrollably. The solution is to elevate the canal over the waterway via a bridge. In essence, a large, elevated bathtub must be built—water cannot be leaking out of the bottom and sides. This is done with a thick layer of clay and stone on the bottom and solid stone walls for sides.

Illustration of an aqueduct–the Catoctin Aqueduct–in use

Lock 52 and the Tonoloway Creek Aqueduct on the Chesapeake and Ohio Canal were built between the fall of 1835 and the spring of 1839. The lock and aqueduct are so close to each other that they are practically one continuous structure similar to the Seneca Creek Aqueduct and Lock 24. However, there is a very short separation between the two. If traveling downstream from Cumberland, canal boats came to the aqueduct first, then immediately entered Lock 52. Vice versa if traveling upstream from Washington.

View upstream from Lock 52 towards the Tonoloway Creek Aqueduct, Chesapeake and Ohio Canal National Historical Park

Upstream view of the Tonoloway Creek Aqueduct on the Chesapeake and Ohio Canal

The Tonoloway Creek Aqueduct is no longer capable of holding water due to the loss of both of its parapets (retaining walls) sometime after the mid-1930s, which was long after the Chesapeake and Ohio Canal was out of business. The aqueduct was plagued with problems since it went into operation. The stone berm-side parapet (opposite the towpath) was rebuilt in 1873-74 after it began bulging, a sign of an eminent collapse. The stone parapet did collapse in the 1880s and was replaced with wood, which while being far from leak-proof, was a cheap repair that held up for many years.

Missing berm-side parapet of the Tonoloway Creek Aqueduct on the Chesapeake and Ohio Canal

Of the eleven aqueducts on the Chesapeake and Ohio Canal, six are single-arch structures, with the Tonoloway Creek Aqueduct being one of them. Its arch is currently shored up with iron rods that were put in place by the National Park Service.

Iron rods support the arch of the Tonoloway Creek Aqueduct on the Chesapeake and Ohio Canal

Some of the aqueduct’s original wrought-iron railing still survives. Original railing also exists at the Monocacy Aqueduct and the Catoctin Creek Aqueduct.

Original railing of the Tonoloway Creek Aqueduct on the Chesapeake and Ohio Canal

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