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.
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 of 81 (54 percent) NTN stations analyzed. The median reduction in nitrogen load, for these 44 NTN stations, is 0.68 pounds per acre or 10 percent. Trends in phosphorus loads are improving at 41 of 60 (68 percent) NTN stations analyzed. The median reduction in phosphorus load, for these 41 NTN stations, is 0.11 pounds per acre or 24.7 percent. Trends in suspended-sediment loads are improving at 29 of 59 (49 percent) NTN stations analyzed. The medina reduction in suspended-sediment load, for these 29 NTN stations, is 221 pounds per acre or 29.4 percent.