The Chesapeake Bay Watershed Now what is the Chesapeake Bay Watershed? Well for starters, what is a watershed? A watershed is the total land area that drains water into a body of water. Watersheds can be big or small, and the Chesapeake Bay Watershed is definitely big! The Watershed includes six states. Those states are: Maryland Virginia West Virginia Delaware Pennsylvania New York However, having such a large watershed isn't always good. Anything that water can carry, good or bad for the bay, can make its way and eventually end up in the bay. Used oil, gasoline, pesticides, and many other harmful substances enter the bay this way. The activites of people who inhabit the watershed have huge effects on the Chesapeake Bay. If it rains at a nearby farm, the fertilizer can enter rivers. Those rivers lead to none other than the Chesapeake Bay! Even the weather can impact the bay and its watershed. If an area of the watershed has a rainy season, rivers in that area will have more fresh water. That fresh water will make it to the bay through those rivers, and it will decrease the salinity of the bay. Below is a map of the watershed.