Chapter 01 - A Tour around the Chesapeake Bay
The Bay is often divided into three regions, the Upper Bay, from the Susquehanna River and the Flats to the Bay Bridge, the Middle Bay from the Bay Bridge to the mouth of the Potomac, and the Lower Bay, from the Potomac to the Atlantic Ocean. Each has its own unique character.
The following sections will attempt to characterize and give the flavor of each region and introduce some of the kayak opportunites available.
The division of the bay into three zones is not completely arbitrary, but is aligned with the character of the land, rivers and the Bay waters of each region. Being an estautary, a semi-enclosed body of water open to the sea, the salinity (amount of salts dissolved in the water) dominates the environment for the many creatures that call the Bay home. From fresh water in the rivers with significant water flows, to brackish water even at the head of the languid tidal rivers emptying into the Middle Bay, to open salt marshes and the Atlantic Ocean itself at the Bay's mouth, the Bay experience includes all types of coastal ecosystems. These systems move up and down the Bay with the tides and the seasons. Note how the salinity of the entire Chesapeake Bay increases as the summer season reduces the amount of fresh water entering the Bay from its primary tributary, the Susaquehanna River.
Department of Natural Resources State of Maryland
These maps support a generalized distinction between the fresh Upper Bay and salty Lower Bay, with the transitional Middle Bay seeing the greatest change in salinity during the seasons. The major flowing rivers of the Potomac and the James show a similar seasonal salinity intrusion as the main Bay. The Susquehanna River and the Susquehanna Flats, all the way at the head of the Bay and with a highest flow rate, is essentially fresh all year long. Half of the fresh water entering the Chesapeake Bay comes from the Susquehanna River.
The salinity of the water and the geography of the land are linked in that the steeper, higher banks of the Upper Bay and the western rivers are also responsible for higher inputs of fresh water and a greater watershed area. This general trend can be seen in the salinity diagrams above, particularly in the spring, as the fresh water from the western watershed prevents the salt water intrusion from reaching as far into the bay along the Western shore. The higher banks of the Western shore and in the Upper Bay, give a character to the land along the shore, and the low lying land and marshes of the Easern shore further distinguish the three regions.
The Chesapeake Bay contains multiple distict natural communities as well. These communities are defined by the interplay of light, nutirients and the salinity.
The following sections seek to capture the essence of the Bay regions from the perspective of a kayaker.