Stations Analyzed are 01578310 - SUSQUEHANNA RIVER AT CONOWINGO, MD and 01646580 - POTOMAC RIVER AT CHAIN BRIDGE NEAR WASHINGTON, DC. 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 spring nitrogen loadings to support an annual forecast of summer Chesapeake Bay conditions. This 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 2016.