The Susquehanna and the Chesapeake Bay

The Susquehanna River (originally "Sasquesahanough" on the 1612 map by John Smith) is approximately 444 miles (715 km) long. It is the longest river on the American east coast and the 16th longest in the United States.

The Susquehanna has two main branches, with the North Branch, which rises in upstate New York often regarded as an extension of the main branch. The shorter West Branch, which rises in western Pennsylvania, is often regarded as the principal tributary, joining the North Branch near Northumberland in central Pennsylvania.

The Susquehanna drains 27,500 square miles (71,225 km²), covering nearly half of the land area of Pennsylvania and portions of New York and Maryland. The river empties into the northern end of the Chesapeake Bay at Havre de Grace, Maryland, providing half of the freshwater inflow for the bay.

The Susquehanna receives sediment and pollution from stream channel erosion, agricultural runoff, urban and suburban storm water, raw or inadequately treated sewage, and abandoned mine drainage. The U.S. Environmental Protection Agency (EPA) has identified suspended sediment as the most critical pollutant to mitigate.

In 2003 the Susquehanna River contributed 21% of the sediment, 44% of the nitrogen, and 21% of the phosphorus flowing into the Chesapeake Bay. As a result of missing a 2010 deadline to reduce nutrient loads sufficiently to restore the bay ecosystem, EPA is currently establishing a mandatory “nutrient diet” or total maximum daily load (TMDL) for nitrate and phosphate levels in the watershed.

Recent assessments of the watershed’s health vary considerably. In 2005, for example, the agency American Rivers identified the Susquehanna as America’s Most Endangered River while the Pennsylvania Department of Conservation and Natural Resources awarded the West Branch of the Susquehanna the River of the Year.

Continued collaboration between scientists at universities, state and federal agencies, and public watershed groups is needed to arrive at an accurate assessment of the river and identify ways to improve conditions in the watershed.