Baltimore Harbor Watershed Nutrient TMDL Restoration Plan Anne Arundel County, Maryland November 2016 - Final Baltimore Harbor Watershed Nutrient TMDL Restoration Plan November 2016 - Final Prepared for: Anne Arundel County Department of Public Works Watershed Protection and Restoration Program 2662 Riva Road Annapolis, Maryland 21401 Prepared by: KCI Technologies, Inc. 936 Ridgebrook Road Sparks, Maryland 21152 Baltimore Harbor Watershed Nutrient TMDL Restoration Plan 2016 Table of Contents 1 Introduction ..................................................................................................................... 1 1.1 Background and Purpose .............................................................................................................. 1 1.2 TMDL Allocated and Planned Loads Summary ............................................................................. 3 1.2.1 Reduction Target Derivation ................................................................................................. 6 1.3 Restoration Plan Elements and Structure ..................................................................................... 9 2 Watershed Characteristics ............................................................................................. 11 2.1 Watershed Delineation ............................................................................................................... 11 2.2 Baltimore Harbor Watershed...................................................................................................... 11 2.3 Land Use/Land Cover .................................................................................................................. 14 2.3.1 Existing Land Use/Land Cover ............................................................................................. 14 2.3.2 Impervious Surfaces ............................................................................................................ 15 2.4 Water Quality .............................................................................................................................. 19 2.4.1 Use Designations ................................................................................................................. 19 2.4.2 TMDLs and 303(d) Impairments ......................................................................................... 19 2.4.3 NPDES .................................................................................................................................. 21 3 Causes and Sources of Impairment (a) ........................................................................... 23 3.1 Impairments ................................................................................................................................ 23 3.2 Sources ........................................................................................................................................ 23 3.2.1 Urban Stormwater Runoff .................................................................................................. 23 3.2.2 In‐stream Sources ............................................................................................................... 24 3.3 Anticipated Growth ..................................................................................................................... 29 3.3.1 Offsetting Loads from Future Growth ................................................................................ 30 3.3.2 Estimates of Future Growth ................................................................................................ 30 4 Management Measures (c) ............................................................................................ 35 4.1 Modeling Approach..................................................................................................................... 35 4.2 Best Management Practices ....................................................................................................... 35 5 Expected Load Reductions (b) ........................................................................................ 38 5.1 2015 Progress – Actual Implementation ..................................................................................... 38 5.2 Planned Implementation ............................................................................................................ 43 6 Technical and Financial Assistance Needs (d) ................................................................. 46 6.1 Funding Sources .......................................................................................................................... 48 7 Public Participation / Education (e) ................................................................................ 49 7.1 County Outreach Efforts ............................................................................................................. 49 7.2 Public Comment Period .............................................................................................................. 51 8 Implementation Schedule and Milestones (f & g) .......................................................... 51 8.1 Implementation Milestones ........................................................................................................ 51 8.2 Loading Allocations and Milestone Targets ................................................................................ 52 8.3 Implementation Priorities ........................................................................................................... 53 8.3.1 Stream Reach Restoration .................................................................................................. 53 8.3.2 Subwatershed Restoration ................................................................................................. 57 8.3.3 Prioritization of Strategy Implementation .......................................................................... 59 i Anne Arundel County DPW Baltimore Harbor Watershed Nutrient TMDL Restoration Plan 2016 9 Load Reduction Evaluation Criteria (h) ........................................................................... 59 9.1 Tracking Implementation of Management Measures ................................................................ 59 9.2 Estimating Load Reductions ........................................................................................................ 62 9.3 Tracking Overall Program Success through Monitoring ............................................................. 62 9.4 Best Management Practices Inspection and Maintenance ........................................................ 62 10 Monitoring (i) ................................................................................................................ 63 11 References ..................................................................................................................... 66 List of Tables Table 1: Baltimore Harbor Watershed Local TMDL Allocated and Planned Annual Average Loads ............ 6 Table 2: Disaggregated and Calibrated Baltimore Harbor Watershed Local TMDL SW‐WLAs and Load Reductions .................................................................................................................................................... 8 Table 3: Baltimore Harbor Watershed Drainage Area and Stream Miles ................................................... 12 Table 4: 2014 Land Use / Land Cover .......................................................................................................... 14 Table 5: Baltimore Harbor Watershed Percent Impervious Cover ............................................................. 15 Table 6: Use Designations of the Baltimore Harbor Watershed ................................................................ 19 Table 7: Category 4a and 5 Listings for Anne Arundel County's Portion of the Baltimore Harbor Watershed ................................................................................................................................................... 20 Table 8: Erosion Inventory and Severity per Subwatershed (Anne Arundel County, 2011 and 2012b) ..... 27 Table 9: Linear Feet of Erosion per Subwatershed (Anne Arundel County, 2011 and 2012b) ................... 28 Table 10: Increases in Land Use and Pollutant Loads from 2010 through 2015 ........................................ 31 Table 11: Estimated Future Increases in Pollutant Loads ........................................................................... 32 Table 12: Typical Nutrient Reduction from Stormwater BMPs .................................................................. 37 Table 13: Nutrient Loads Required for the Baltimore Harbor Watershed Local TMDL – Disaggregated to Anne Arundel County Phase I MS4 Source and Calibrated to BayFAST ...................................................... 38 Table 14: Current BMP Implementation through FY2015 for Baltimore Harbor Watershed ..................... 39 Table 15 – List of streets swept in Baltimore Harbor watershed ............................................................... 39 Table 16: FY2015 Progress Reductions Achieved ....................................................................................... 43 Table 17: BMP Implementation ‐ Current FY2015, Planned FY2030, and Total Restoration Levels for the Baltimore Harbor Watershed ..................................................................................................................... 44 Table 18: FY2030 Planned Reductions