From Wikipedia
The Lehigh Canal, designed by Canvass White, an engineer of New York's Erie Canal, was constructed between 1827 and 1829. The enlarged Lehigh Navigation extended 46 miles (74 km) between Mauch Chunk, Pennsylvania (present-day Jim Thorpe) and Easton with 52 locks, eight guard locks, eight dams and six aqueducts, allowing the waterway to overcome a difference in elevation of over 350 feet (107 m). A weigh lock determined canal boat fees a half mile (1 km) south of Mauch Chunk. A connection across the Delaware River to the Morris Canal through New Jersey allowed the coal from the Lehigh Canal to be shipped more directly to New York City.
During the 1830s, an extension of 26 miles (42 km) to White Haven, Pennsylvania, which included 20 dams and 29 locks, was constructed, covering a difference in elevation of over 600 feet (183 m) to Mauch Chunk.
In 1855, the canal reached its peak of more than one million tons of cargo. However, competition from railroads and the catastrophic flood of June 4, 1862, were all steps towards the canal's demise. The canal was used as a means of transportation until the 1940s (about a decade after other similar canals ceased operations), making it the last fully functioning towpath canal in North America. In 1962, most of it was sold to private and public organizations for recreational use.
I know of only one dam on the Delaware aside from the 3 wing dams, an old wooden structure, that I believe still exists at Lackawaxen PA just south of the Confluence of the Lackawaxen R. before the Roebling Viaduct. I found it when wading that section of the river when fishing. That doesn't mean there were more dams, but the books about the Delaware don't talk about them.
The Dam at Lackawaxen was contriversial in it's day because loggers were already running log rafts from the Upper Delaware River by the early 1800's, and didn't want to deal with going over the dam. The dam was eventually removed in favor of the viaduct. The dam was built for crossing canal boats across the Delaware
