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Geography & Population

The Susquehanna River Watershed is the largest watershed in the United States that drains into the Atlantic Ocean, and the largest east of the Mississippi.

  • 27,500 square miles in New York, Pennsylvania, and Maryland.
  • 43% of the Chesapeake Bay Watershed’s 64,000 square miles;
  • 46% of the state of Pennsylvania, 20,900 square miles;
  • 13% of New York, 6,300 square miles; and
  • less than 1% of Maryland with 300 square miles.

[Click here to see a map of the Lower Susquehanna Subbasin.]

The quality and quantity of waters from the Susquehanna and its tributaries directly affect the Bay’s health and productivity. Over 90% of the Upper Chesapeake Bay’s freshwater comes from the Susquehanna, and it provides over 50% of the total volume of the Bay. Every day, the Susquehanna adds 22-25 billion gallons of water containing pollutants to Chesapeake Bay.

Every drop passes through the Lower Susquehanna Subbasin.

The focus of the Lower Susquehanna Riverkeeper® program is the Lower Susquehanna and Juniata Subbasins.

  • 9,215 square miles, or roughly one third of the total Susquehanna Watershed.
  • 54% of the total watershed population, or 2.5 million of the 4.5 million people in the watershed.
  • Harrisburg, Lancaster, York, Lebanon, Altoona, Carlisle and Lewistown all grew along the tributaries of the Lower Susquehanna.
  • Tributaries: Juniata River, Little Juniata, Codorus, Conestoga, Conodoguinet, Swatara, Conewago, Penn’s, and Sherman’s Creeks

Today, the majority of agriculture, industry, overdevelopment, and water flow impairments in the Susquehanna Watershed are in these two southern subbasins.

In 2005, American Rivers named the Susquehanna River America’s Most Endangered River. Many of the causes for this designation – combined sewage overflows, rampant agricultural pollution, rapid deforestation and lost farmlands – are found to the greatest degree in the Lower Susquehanna and Juniata watersheds.

In 2011, American Rivers named the Susquehanna River America’s Most Endangered River for a SECOND time. This dubious ‘honor’ was applied due to the rush to develop shale gas reserves with limited and myopic consideration of impacts to clean water, rivers, and community health. Today’s natural gas status quo comes with a price tag and the price – dirty water and a squandered future – is more than we can afford.