The Musconetcong River is a 45.7-mile-long (73.5 km)tributary of the Delaware River in northwestern New Jersey in the United States. It flows through the rural mountainous country of northwestern New Jersey. Part of it is a National Wild and Scenic River.
It rises out of Lake Hopatcong, on the border between Sussex and Morris counties. It flows through Lake Musconetcong, then flows southwest, past Stephensburg and New Hampton, passing south of Washington then along the southeastern side of the Pohatcong Mountain ridge. It joins the Delaware across from Riegelsville, Pennsylvania, approximately 10 mi (16 km) south of Phillipsburg.
The river does not flow through any large population center and has been the site of relatively little industrial development throughout its history. In the 18th century, the surrounding hills were largely deforested as a source of charcoal for the iron industry in the surrounding region. The local industry declined by the middle of the 19th century after the building of the former Morris Canal, the course of which ran along the upper river, to bring coal from Pennsylvania to northern New Jersey. After the demise of the canal from the introduction of railroads in the late 19th century, the dam pools along the river that supplied the canal became the site of a popular summer cottage industry. Silted remnants of the pools, as well as the remnants of the canal itself, can still be seen along the river.