Annual winter-spring nitrogen loads for the Susquehanna and Potomac Rivers, 1985 to 2018

Winter-spring nitrogen loads as measured at the Susquehanna River at Conowingo Maryland and Potomac River at Washington, D.C. have been determined to be an effective indicator of summer anoxic and hypoxic volume in Chesapeake Bay. The U.S. Geological Survey (USGS) provides an estimate of winter-spring nitrogen loadings to support an annual forecast of summer Chesapeake Bay conditions. The specific period of estimation includes the months of January through May. This forecast is coordinated through an established relationship with the National Oceanic and Atmospheric Administration (NOAA), University of Maryland Center for Estuarine Science (UMCES) and Maryland's Department of Natural Resources. The results presented here are updated annually, and are revised as additional monitoring results are available. The results presented here cover the period 1985 through 2018.