1. Answering the Question: Why? Factors Affecting Change in Water Quality Exceptional challenge to explain “why” Poor quality of pollution source information Ex. Ag source sector has poor information on BMP implementation (due in part to Farm Bill privacy issues and technical limitations of NRCS.) Many assumptions (with errors associated with them) are required to generate a time series of source information Lag time issue of pollutants in surface and ground water Expectation for change is not realistic given degree of management practice implementation Explaining change is hard in large rivers given multiple pollutants however, explaining change in the point sources is possible Ex. Point source controls are the explanation for most decreases in nutrients in large CBW rivers since 1980s Smaller systems allow for understanding of factors affecting change Monitoring is moving to from large river focus to monitoring some small watersheds where large amounts of practice implementation is planned or ongoing in order to better describe factors affection change. Point source easier to explain than non point source

2. Flow-Adjusted Concentration Trends 1985-2008: Total Phosphorus 22 downward trends 4 upward trends 8 non-significant trends

3. Flow-Adjusted Concentration Trends 1985-2008: Total Nitrogen 25 downward trends 2 upward trends 7 non-significant trends

4. Flow-Adjusted Concentration Trends 1985-2008: Total Sediment 13 downward trends 2 upward trends 19 non-significant trends

5. Wastewater Discharge Locations: Patuxent River Watershed Data Source: Chesapeake Bay Program: Point Source Database 20 Locations upstream from USGS Patuxent River Gage Significant Investment(s) in treatment technology Phosphorus Detergent Ban Watershed Changes: Urban/Suburban devt. Land Conversion Population increase NPS management SWM management

6. Large Point-Source Reductions Yield Measurable Improvements in Phosphorus Concentrations Annual Point source Discharges Upstream from Patuxent River Monitoring Station Observed Concentrations at Patuxent River Monitoring Station

7. 44 years of Nitrate concentration data show long-term increases in an agricultural setting: Choptank River at Greensboro, MD

8. Groundwater Models Develop Nutrient Loading Forecasts