Patapsco and Back River HSPF Watershed Model

1. Patapsco and Back River HSPF Watershed Model Part II – Water Quality Maryland Department of the Environment

2. Introduction • Water Quality Data • Model Inputs • Calibration Procedure • Model Comparisons • Summary

3. Water Quality Data • Data Sources • Department of Natural Resources Monthly values for NH3, NO3, TN, PO4, TP, TOC, DO, TSS, Temperature • Baltimore City* Storm event and base flow values for TSS, TOC, TN and TP *City of Baltimore Comprehensive Wastewater Facilities Master Planning Project

5. Model Inputs • Atmospheric Deposition • Septic Loads • Point Sources • Manure and Application

6. Atmospheric Deposition • Deposition is input as NO3 (wet and dry) and NH3 • Used CBP time series • Avg. Annual NO3 7.05 lb/acre • Avg. Annual NH3 2.08 lb/acre

7. Septic Loads • Number of septic users were calculated on County basis using Census data compiled by EPA. • Used GIS to allocate to watershed segmentation • Assume NO3 loading coefficient of 0.0256 lb/person/day. • Assume 60% reduction in NO3 • Assume 100% retention of Phosphorus

8. Manure and Application • Animal Counts – Used to calculate Manure Acres which is simulated as an impervious land use • Manure acres is a derived land use which represents what is susceptible to runoff from confined animals within a model segment.

9. Manure/Mineral Fertilizer Application • Manure Calculations (based on MDA and U of MD recommendations)

10. Calibration Procedure • Focus on predominant land uses • Calibrate EOS loads to literature values • Calibrate urban loads to Event Mean Concentrations (EMCs) • Time series overlay

11. Unit Loading Rates (Literature Values) Literature Sources: Jones Falls Water Quality Management Plan, Loch Raven Water Quality Management Plan, Baltimore County NPDES 2000, Harford County NPDES 1999 and 2000, City of Baltimore NPDES 1999, Center for Watershed Protection and Ken Staver (University of MD).

12. Patapsco/Back Estimated Average Annual Loads and Percent Contributions Load = Loading Rate x Area

13. Estimated and Final Model EOS Loads

14. Urban EMCs

17. Jones Falls Water Quality Calibration • Calibration at Station JON0184 • Parameters calibrated: DO, Temperature, TOC, TSS, PO4, TP, NH3, NO3, ChlA and TN

25. Patapsco (Hollofield) Branch Water Quality Calibration • Calibration at Station PAT0285 • Parameters calibrated: DO, Temperature, TOC, TSS, PO4, TP, NH3, NO3, ChlA and TN

33. Summary/Comparisons • Unit loads, EOS and Delivered loads compared to existing studies • Discussion of model loads and comparison

34. Comparison of Unit Loading Rates

35. Total Average Annual EOS Loads Summary

36. Total Delivered Loads Summary

37. Back River Comparisons

38. Comparison of CBP and MDE Model • Model Scale • Hydrology Calibration • Water Quality Calibration • Urban Calibration

39. CBP Segmentation

40. MDE Segmentation

41. Hydrology Calibration

42. Water Quality Calibration

43. Urban Calibration • NPDES Storm Water Data vs. National Urban Runoff Program (NURP) Data • CBP reductions to Urban Loads - Reductions to Urban Loads of 15% TN and 30% TP* * Based on numbers from Urban Watershed Group

44. Summary • MDE hydrology calibrated to 3 gages. CBP model hydrology calibrated to 1 gage. • MDE water quality calibrated to 4 gages. CBP model water quality calibrated to 1 gage. • MDE urban land use calibrated to local NPDES data. CBP calibrated to NURP data. • It can be concluded that the final load differences between the MDE and CBP models are due to these factors.