At the head of the Chesapeake Bay Watershed is the Susquehanna River. Flowing more than 400 miles, it is the longest Atlantic U.S. river and one of North America’s largest rivers.
The river drains 27,500 square miles, including parts of Pennsylvania, New York, and Maryland.
The Susquehanna originates in upstate New York as the North Branch. The West Branch, which begins in western Pennsylvania, converges with the North Branch near Northumberland, Pa.
On the lower stretch of the river, a reservoir system consisting of Lake Clarke, Lake Aldred, and Conowingo Reservoir is formed by three consecutive hydroelectric dams. Safe Harbor Dam forms Lake Clarke. Holtwood Dam, the smallest of the three, forms Lake Aldred. The largest and most downstream dam, Conowingo Dam, forms Conowingo Reservoir.
Below the Conowingo Dam, the river widens at the Susquehanna Flats, one of the bay’s most unique habitats. The area contains an abundance of shallow water with a mix of submerged aquatic vegetation, and sandy or muddy flats.
Water clarity and salinity varies considerably in the Susquehanna Flats, depending on weather, river flow, and other factors. Below the Susquehanna Flats, the Chesapeake Bay becomes a higher salinity estuary.
Fishing
The Susquehanna is one of the most popular rivers for fishing in the Chesapeake watershed. The river has produced numerous state record fish and other notable catches.
In February 2025, Thomas Dembeck Jr. became the new Maryland state record holder for yellow perch in the Chesapeake division. Dembeck caught the 2.3-pound, 16-inch fish while deep jigging in about 50 feet of water in the lower Susquehanna River.
In January, 2024, Thomas Over Jr. caught a 1.0-pound rock bass in the lower Susquehanna River, tying the Maryland state record – Chesapeake Division for the species.
In May 2023, angler Michael Wherley, 46, caught a monster flathead catfish on the Susquehanna River section known as Lake Aldred. Weighing 66 pounds, 6 ounces, with a length of 50.25 inches a girth of 35 inches, Wherley’s fish broke the existing Pennsylvania state record for the species by more than ten pounds.
In June 2022, Logan Kuhrmann became the Maryland state record holder for common carp in the Chesapeake Division. Kuhrmann caught the 49-pound carp while bass fishing in the Susquehanna Flats area.
In 2020, Joshua Dixon was officially been recognized by the Maryland Department of Natural Resources (DNR) as the first-ever state record holder for the invasive flathead catfish. Dixon caught the 57-pound, 50-inch long flathead catfish while fishing near the Lapidum Boat Ramp on the Susquehanna River.
In April, 2019, angler Jeff Bonawitz caught a monster flathead catfish in the Susquehanna river. Weighing 50 pounds, 7 ounces, with a length of 45.25 inches and girth of 31.25 inches, Bonawitz’s fish held the Pennsylvania state record for a time. The monster catfish was released alive back to the Susquehanna River beneath the Wrightsville Bridge.
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