The Susquehanna River, one of the longest rivers on the East Coast, is a significant natural resource that spans 444 miles from New York through Pennsylvania and Maryland before emptying into the Chesapeake Bay. The river’s vast watershed, covering over 27,500 square miles, supplies approximately 50% of the Chesapeake Bay’s freshwater inflow, directly influencing the health of the entire estuary. The question of whether the Susquehanna is “clean” is complex, as its water quality varies significantly along its length and is highly localized, depending on the proximity to pollution sources. The river’s status is a dynamic state of impairment and ongoing recovery.
Defining “Clean” and Current Status
Water quality is assessed using a combination of chemical, physical, and biological metrics, which together determine if a waterway supports aquatic life and is safe for human use. Key indicators monitored by agencies like the Susquehanna River Basin Commission (SRBC) include dissolved oxygen (DO), pH levels, and the concentration of nutrients and sediment. Biological health is also measured through indices that assess the diversity and health of aquatic insects and fish communities.
The river is generally categorized as impaired, particularly in its tributaries and the lower main stem, with over 7,100 miles of streams in the basin unable to fully support aquatic life or safe human use. Water quality stress is often characterized by conditions like low dissolved oxygen, which occurs when excessive nutrients fuel algal blooms that consume oxygen upon decomposition. The Susquehanna contributes substantial loads of pollutants to the Chesapeake Bay, accounting for about 44% of the nitrogen, 21% of the phosphorus, and 21% of the sediment entering the estuary.
Primary Sources of Impairment
The river’s water quality challenges stem from three major sources that have impacted its watershed for decades.
Agricultural Runoff
Agricultural runoff is the single largest source of pollution, carrying tremendous loads of nitrogen and phosphorus from fertilizers and animal manure. Across Pennsylvania, livestock produce millions of tons of manure annually, resulting in excess nutrients that enter local waterways and groundwater. Nitrate levels in groundwater samples in the lower Susquehanna region can exceed the safe drinking water maximum contaminant level of 10 milligrams per liter in nearly half of the wells tested.
Abandoned Mine Drainage (AMD)
A second significant issue is legacy pollution from abandoned mine drainage (AMD) in the upper and western portions of the watershed. When water and oxygen interact with pyrite in abandoned coal mines, it creates sulfuric acid and leaches heavy metals like iron and aluminum. This AMD can reduce the stream’s pH to highly acidic levels, which is highly toxic to fish and macroinvertebrates. The resulting iron-oxide precipitates often coat stream bottoms in a distinctive orange sludge, essentially sterilizing the aquatic habitat.
Urban Stormwater and Wastewater
Urban and suburban areas contribute a third source of pollution through stormwater runoff and wastewater overflows. Impervious surfaces like roads and parking lots prevent rainfall from soaking into the ground, instead channeling it rapidly into streams, which causes streambank erosion and carries pollutants. This runoff contains a mix of contaminants, including pathogens, heavy metals, and emerging concerns like endocrine-disrupting compounds from treated wastewater, which have been linked to health issues in fish populations.
Safety for Recreation and Consumption
Recreation Safety
The river’s water quality directly affects the safety of recreational activities and the consumption of fish caught in its waters. For activities involving direct contact, such as swimming or kayaking, bacterial contamination is a primary concern, particularly in tributaries near populated areas. High levels of E. coli, an indicator of fecal contamination from sources like manure runoff and failing septic systems, are frequently detected, especially following heavy rainfall. Local advisories often recommend avoiding water contact when E. coli levels exceed the safe limit of 410 MPN/100mL.
Fish Consumption Advisories
In terms of fish consumption, advisories are in place due to the bioaccumulation of contaminants in fish tissue. A statewide recommendation restricts the consumption of all gamefish species to no more than one meal per week due to mercury concentrations. Additionally, in specific segments of the river, particularly in the lower main stem, advisories limit the consumption of species like channel catfish, carp, and walleye to one meal per month due to elevated levels of Polychlorinated Biphenyls (PCBs). These advisories are important for sensitive populations, including pregnant women and children, as they are most susceptible to the health risks associated with these toxins.
Ongoing Restoration and Future Outlook
Restoration efforts are largely coordinated under the Chesapeake Bay Total Maximum Daily Load (TMDL), a federal mandate that sets a pollution cap for nitrogen, phosphorus, and sediment entering the Bay. Pennsylvania’s strategy is designed to meet this mandate, with specific reduction goals for millions of pounds of these pollutants annually. This policy framework drives on-the-ground projects throughout the Susquehanna watershed.
One of the most effective pollution control strategies is the establishment of riparian forest buffers, which are strips of trees and shrubs planted along stream banks. These buffers physically filter nutrient and sediment runoff, stabilize stream banks to reduce erosion, and provide shade to keep water temperatures cool for aquatic life. Government programs and conservation groups are actively working with landowners to implement these best management practices, with thousands of miles of buffers either being restored or targeted for planting.