Fresh water enters the Chesapeake Bay primarily from its rivers and streams. Fresh water also enters via rain, snow and groundwater.

The Chesapeake Bay’s salinity gradually decreases as you move north and increases as you move south. Salinity also varies widely from season to season and from year to year, depending on the amount of fresh water flowing from the Bay’s rivers.

Poor water clarity is usually caused by a combination of suspended sediments, organic matter and excess nutrients that fuel the growth of water-clouding algae. Weather also plays a large role in water clarity. Rain storms can wash dirt and pollutants into the Bay and cause the water to look muddy. During drier conditions, the water is usually clearer.