This private ownership continued until a local representative, Samuel Frank, promoted a bill to return control of the river to the state in 1967.

According to an environmental report from a Pennsylvania nonprofit research center, the Lehigh River watershed is ranked second nationally in the volume of toxic substances released into it in 2020.

The study mirrored a previous report by the state's Department of Environmental Protection that found most of the county's waterways unsafe for swimming or aquatic life.

Its lower course forms the heart of the Lehigh Valley, a historically important anthracite coal and steel-producing region of Pennsylvania.

The river rises in the Poconos region of northeastern Pennsylvania in several ponds in Lehigh Township in Wayne County, approximately 15 miles (24 km) southeast of Scranton.

Near White Haven, it turns south, following a zigzag whitewater course through Lehigh Gorge State Park to Jim Thorpe, then southeast, past Lehighton.

Over the years since 2005 various groups such as the Lehigh Coldwater Fishery Alliance and the Pennsylvania Fish and Boat Commission have worked with the Army Corps of Engineers to design annual flow plans[3] from the Frances Walter Dam (F.E.W.)