A watershed is the area of land that drains to a stream, river, or other water body. The discharges of water and other materials that flow off a watershed tell a story about how water interacts with human activities and natural processes on land. Watershed discharges also shape downstream aquatic life by delivering both essential water and nutrients, as well as harmful pollutants. Excessive flows of nitrogen and phosphorus can create massive algal blooms that block light and drain oxygen from the water, creating “dead zones.” Sediment can also cloud the water, making it difficult for anything, even algae, to photosynthesize.

SERC scientists have studied watershed discharges throughout the center’s history. They seek to understand what controls the transfer of materials from the land to the water, and how those materials affect aquatic ecosystems. They have set up hundreds of stream monitoring stations to measure the amounts of water, sediment, nutrients (nitrogen, phosphorus, and carbon), and other chemicals leaving watersheds. They relate differences in discharge among watersheds to climate, land use, geology and land management. Researchers also examine weather, changes in land use and climate change to understand why watershed discharges change through time.

SERC’s watershed research focused first on SERC’s home—the Rhode River watershed.  From there, the research has expanded to studies of the 64,000-square-mile watershed of Chesapeake Bay and to studies of the entire United States.