Douglas L. Moyer is a supervisory hydrologist with the U.S. Geological Survey, with over 15 years experience in nutrient and sediment transport within the Chesapeake Bay watershed. He serves as a Principal Investigator for the determination of nutrient and sediment loads and trends for all monitoring stations in the Chesapeake Bay Nontidal Monitoring Network.
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.
Long-term (1985-2014) trends in nitrogen loads indicate improving conditions at the 7 of 9 RIM stations, including the five largest rivers. The Choptank River is the only station whose data indicate degrading conditions. Short-term (2005-2014) trends in total nitrogen loads indicate improving conditions at only 3 stations and degrading conditions at 4 stations. Results from the Susquehanna and James stations indicate no discernable short-term trends. Long-term trends in total phosphorus loads indicate improving conditions at 4 stations and degrading conditions at another 4 stations. Short-term trends in total phosphorus loads indicate improving conditions at only the Potomac and Patuxent stations, degrading conditions at 4 stations, and no discernable change in conditions at the 3 remaining stations.