IAN Seminar Series

The U.S. Geological Survey (USGS), as a partner of the Chesapeake Bay Program, is responsible for determining the extent to which nitrogen, phosphorus, and suspended-sediment loads delivered to bay from the monitored-nontidal portions of the bay watershed. This is accomplished by analyzing water-quality observations from the nine River-Input Monitoring (RIM) stations to estimate nitrogen, phosphorus, and suspended-sediment annual loads and trends using Weighted Regressions on Time, Discharge, and Season (WRTDS). The resulting trends in nitrogen, phosphorus, and sediment loads are flow normalized to account for the year-to-year variation in river discharge; thus, the remaining trend is a result of changing sources, delays associated with storage or transport of historical inputs, and/or implemented reduction strategies.Nitrogen, phosphorus, and suspended-sediment loads are showing measurable improvement at many locations across the bay watershed from 2005 to 2014. Trends in nitrogen loads are improving at 44 o