Too much nitrogen and phosphorus contribute to ecological problems in the Bay, including major declines in fish and shellfish populations. The Bay's 64,000 square mile watershed can be subdivided into smaller watersheds that supply individual rivers or streams. By measuring stream nutrient levels in small watersheds throughout the Bay's drainage, SERC researchers have found differences in nutrient discharges among major geological regions. For example, streams in Piedmont and Appalachian geological provinces carry more nitrogen per acre of cropland than do streams on the Coastal plain. Land use in the Muddy Creek watershed SERC's watershed research also examines how the arrangement of land uses affects nutrient discharges.
Water moving toward a stream passes through one or more land use patches.
Some patches, like fertilized cropland, add nutrients to the water. Other patches, like streamside forests can remove nutrients. At the Rhode River watershed, SERC scientists are testing methods for measuring these effects. Maps and aerial photographs provide essential information on surface elevations, land use patches, and other watershed features. Maps often don't show the small streams where most water first enters the stream network.