DRAFT Wicomico River
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Final Wicomico River Watershed Management Plan March 1, 2013 PREPARED FOR: PREPARED BY: 8390 Main Street, 2nd Floor Ellicott City, MD 21043 www.cwp.org This page has intentionally been left blank. Wicomico River Watershed Management Plan Table of Contents EXECUTIVE SUMMARY .............................................................................................. vi SECTION 1. INTRODUCTION ...................................................................................... 1 1.1 Process for Developing the Wicomico Watershed Management Plan ..................... 1 1.2 U.S. EPA Watershed Planning “A-I Criteria” .......................................................... 2 1.3 Plan Organization ...................................................................................................... 3 1.4 Caveats ...................................................................................................................... 4 SECTION 2. WATERSHED CHARACTERIZATION ................................................ 5 2.1 Introduction ............................................................................................................... 5 2.2 Stream Conditions ..................................................................................................... 9 2.2.1 Total Maximum Daily Loads ........................................................................... 10 2.2.2 Biological Conditions ...................................................................................... 12 2.2.3 Water Quality Conditions ................................................................................ 16 2.2.4 Sources of Impairment ..................................................................................... 21 2.3 Natural Resources ................................................................................................... 23 2.3.1 Ecological Areas .............................................................................................. 23 2.3.2 Protected Lands ................................................................................................ 27 2.4 Classification of Subwatersheds ............................................................................. 28 2.5 Sea Level Rise ......................................................................................................... 30 SECTION 3. WATERSHED ASSESSMENT PROTOCOLS .................................... 32 3.1 Introduction to the Watershed Assessment ............................................................. 32 3.2 Stormwater Retrofit Inventory ................................................................................ 32 3.3 Unified Subwatershed and Site Reconnaissance .................................................... 34 3.3.1 Hotspot Investigations ...................................................................................... 34 3.3.2 Neighborhood Source Assessment ................................................................... 35 3.4 Unified Stream Assessment .................................................................................... 36 SECTION 4. FINDINGS ................................................................................................ 37 4.1 Subwatershed Assessment General Findings .......................................................... 37 4.1.1 Nomenclature ................................................................................................... 37 4.1.2 General Findings .............................................................................................. 38 4.1.3 Lakes and Ponds ............................................................................................... 42 i Wicomico River Watershed Management Plan 4.1.4 Tree Planting Opportunities ............................................................................. 44 4.1.5 Protection Opportunities in the South Prong and Tony Tank Subwatersheds . 45 4.2 South Prong Restoration Opportunities .................................................................. 47 4.2.1 Subwatershed Assessment ............................................................................... 47 4.2.2 Field Assessments ............................................................................................ 49 4.3 Tony Tank Restoration Opportunities..................................................................... 61 4.3.1 Subwatershed Assessment ............................................................................... 61 4.3.2 Field Assessments ............................................................................................ 63 SECTION 5. ACTION PLAN ........................................................................................ 76 5.1. Watershed Restoration Action Strategies .............................................................. 76 5.2 Implementation Planning and Costs ....................................................................... 80 5.3 Monitoring Plan ...................................................................................................... 92 5.4 Project Tracking ...................................................................................................... 93 5.5 Long Term Goals .................................................................................................... 93 REFERENCES ................................................................................................................ 94 List of Figures Figure 2. 1. Wicomico River Watershed .................................................................................... 8 Figure 2. 2. Location and Ranking of Fish Index of Biological Integrity (FIBI) Sites ............ 14 Figure 2. 3. Location and Ranking of Benthic Macroinvertebrate Index of Biological Integrity (IBI) Sites ................................................................................................................................. 15 Figure 2. 4. Average Monthly Total Nitrogen Concentration (mg/l) ....................................... 17 Figure 2. 5. Average Monthly Total Phosphorus Concentration (mg/l) .................................. 17 Figure 2. 6. Total Phosphorus Values for Selected Creekwatcher Sampling Sites.................. 19 Figure 2. 7. Total Nitrogen Values for Selected Creekwatcher Sampling Sites ...................... 20 Figure 2. 8. E.coli and Total Coliform Concentrations in Salisbury Outfalls .......................... 22 Figure 2. 9. Protection and restoration subwatershed priorities as identified by the Core Team .................................................................................................................................................. 30 Figure 2. 10. Sea level rise inundation scenarios for the Wicomico River watershed ............. 31 Figure 4. 1. Wet pond with weir outlet structure to road ditch ................................................ 39 Figure 4. 2. Rain garden opportunity at Prince Street School .................................................. 40 ii Wicomico River Watershed Management Plan Figure 4. 3. Opportunity for ditch restoration in SP_NSA_6. ................................................. 41 Figure 4. 4. Better site design and stormwater treatment reduce phosphorus loading (Caraco, 2001) ........................................................................................................................................ 43 Figure 4. 5. Soil distribution across the South Prong subwatershed ........................................ 48 Figure 4. 6. (a) Bioretention opportunity at SP_RRI_15A; (b) sediment build-up in Ward Museum parking lot (SP_RRI_305A); and (c) existing wet pond at SP_RRI_17 could be retrofit to provide additional water quality treatment .............................................................. 50 Figure 4. 7. (a) Opportunity for stormwater treatment at SP_NSA_15; (b) Opportunity for tree planting around a stormwater pond at SP_NSA_5; and (c) Opportunity for ditch restoration at SP_NSA_6 ............................................................................................................................... 54 Figure 4. 8. (a) Commercial vehicle washing on impervious cover (HSI_20a) and (b) improperly stored materials (HSI_20b) ................................................................................... 54 Figure 4. 9. (a) RCH 13 - "excellent reach" and (b) channelized section of RCH4 - "poor" reach ......................................................................................................................................... 57 Figure 4. 10. (a) Impacted buffer (IBI 701) has been overrun with invasive Japanese knotweed and (b) channel modification (CM 3101) at the airport ........................................................... 58 Figure 4. 11. (a) Very poor stream reach with no buffer and hardened banks (SP_RCH_8); (b) Excellent stream reach with floodplain access and good buffer (SP_RCH_33); and (c) Opportunity for buffer enhancement (SP_IB_501).................................................................. 59 Figure 4. 12. Priority areas for protection in the South Prong subwatershed .......................... 60 Figure 4. 13. Soil Distribution across the Tony Tank subwatershed ....................................... 62 Figure 4. 14. (a) Location for regenerative stormwater conveyance at RRI_41a; (b) wooden box pipe to be removed at RRI_41a; (c) location for bioretention facility to treat parking lot runoff at RRI_41b ...................................................................................................................