Susquehanna Flats

Susquehanna Flats. A vast, shallow-water ecosystem located at the mouth of the Susquehanna River where it meets the Upper Chesapeake Bay in Maryland. This expansive area of tidal marsh and submerged aquatic vegetation is a critical ecological feature of the Chesapeake Bay watershed, renowned for its historical abundance of wild celery and role as a premier waterfowl habitat. The Flats have been a focal point for commercial fishing, recreational boating, and significant environmental restoration efforts within the broader Chesapeake Bay Program.

Geography and hydrology

The Susquehanna Flats are situated directly north of Havre de Grace, forming a massive, shallow delta at the confluence of the Susquehanna River and the Chesapeake Bay. This region is characterized by extremely low gradients and depths often less than six feet, influenced by the immense freshwater flow from the Susquehanna River which drains parts of New York, Pennsylvania, and Maryland. The hydrology is dominated by tidal action from the Chesapeake Bay and sediment loads from the Susquehanna River, which historically created fertile mudflats and sandbars. Key adjacent waterways include the Elk River and the Sassafras River, with the entire area lying within Harford County and Cecil County. The United States Geological Survey has extensively mapped the bathymetry of this region, noting its dynamic nature following major weather events like Hurricane Agnes.

Ecology and wildlife

This ecosystem is internationally recognized as a vital habitat for migratory birds along the Atlantic Flyway, particularly supporting massive flocks of canvasback ducks, tundra swans, and Canada geese. The extensive beds of submerged aquatic vegetation, primarily wild celery and sago pondweed, serve as crucial forage and nursery grounds for fish species including the American shad, striped bass, and white perch. The Flats are part of the Chesapeake Bay National Estuarine Research Reserve system and provide habitat for bald eagles, osprey, and diamondback terrapins. The health of this benthic community is intrinsically linked to water quality and the presence of blue crabs and various mollusks, making it a barometer for the overall condition of the Chesapeake Bay.

Human use and history

For centuries, the Susquehanna Flats have been central to human activity, initially utilized by the Susquehannock people. Since European settlement, the area became famous for a prolific commercial fishing industry, especially for oyster harvesting and haul seine operations for shad and herring. The Chesapeake and Delaware Canal and the Philadelphia, Wilmington and Baltimore Railroad facilitated transport of these resources to markets in Baltimore and Philadelphia. The Flats were a renowned destination for sport fishing and waterfowl hunting, attracting figures like Annie Oakley and contributing to the culture of the Chesapeake Bay log canoe. The Army Corps of Engineers has long been involved in managing navigation and sediment issues in this region.

Environmental concerns and management

The ecosystem experienced severe degradation in the late 20th century, largely due to sediment pollution and nutrient pollution from the Susquehanna River, which caused near-total loss of submerged aquatic vegetation following Hurricane Agnes. Ongoing challenges include harmful algal blooms, turbidity, and impacts from climate change such as sea level rise. Restoration is a primary goal of the Chesapeake Bay Program and the Environmental Protection Agency's Total Maximum Daily Load for the Chesapeake Bay. Key projects involve collaborations between the Maryland Department of Natural Resources, the National Oceanic and Atmospheric Administration, and organizations like the Chesapeake Bay Foundation to replant SAV and reduce nonpoint source pollution. The area is monitored by the Chesapeake Bay Observing System and is subject to regulations from the Atlantic States Marine Fisheries Commission.