Wake-Johnston Collaborative Local Watershed Plan
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Wake-Johnston Collaborative Local Watershed Plan Phase I: Preliminary Findings and Recommendations Neuse River Basin Wake & Johnston Counties, North Carolina August 2013 WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN Section 1 PHASE 1: PRELIMINARY FINDINGS REPORT INTRODUCTION PREFACE The Wake-Johnston Collaborative Local Watershed Plan (LWP) was initiated as a collaborative effort between the Counties of Wake and Johnston and the NC Ecosystem Enhancement Program (EEP). Staff and stakeholders from each interest represented on the General Advisory Committee have participated by actively contributing to project tasks and/or providing input on critical preliminary priorities developed during this first planning phase. In August 2011, the NC Department of Transportation agreed to sponsor a new planning effort, the Neuse 01 Regional Watershed Plan (RWP). This large planning area (580 square miles) encompasses the entire Wake-Johnston Collaborative LWP area, the Upper Swift Creek LWP area, as well as 370 square miles of watershed area not included in a previously studied LWP area. This plan represents the first regional scale plan to be undertaken by EEP and will identify traditional and non-traditional restoration projects to help provide mitigation opportunities generated by the I-540 highway construction within the planning area. Because most elements of the RWP mirror those of the LWP, Phase II and III tasks of the Wake-Johnston Collaborative LWP will be completed as subtasks of the RWP. In Section 6 of this report, the General Advisory Committee proposes recommendations on how best to integrate this local plan into the greater Neuse 01 Regional Watershed Plan. i WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN ACRONYMS PHASE 1: PRELIMINARY FINDINGS REPORT ACRONYMS Below is a list of acronyms used in this document with their corresponding full names. For more complete definitions and explanations of these and other terms, refer to the glossary in Appendix C. AOP Aquatic Organism Passage ATU Aquatic Toxicity Unit ASL Above Sea Level BAU Biological Assessment Unit BEHI Bank Erosion Hazard Index BMP Best Management Practice CU Catalog Unit CWMTF Clean Water Management Trust Fund DBB Design-Bid-Build DEM Digital Elevation Model DENR Department of Environment and Natural Resources DMF Division of Marine Fisheries DSW Division of Soil and Water DWQ Division of Water Quality EEP Ecosystem Enhancement Program EPT Ephemeroptera Plecoptera Trichoptera GAC General Advisory Committee GIS Geographic Information System HU Hydrologic Unit LUP Land Use Plan LIDAR Light Detection and Ranging LWP Local Watershed Plan NCDOT North Carolina Department of Transportation NCFS North Carolina Forest Service NCSU North Carolina State University NHEO Natural Heritage Element Occurrence NHP Natural Heritage Program NLCD National Land Cover Database NPS Non-point Source NRCS Natural Resources Conservation Service NSW Nutrient Sensitive Waters NWI National Wetlands Inventory PFR Preliminary Findings Report PA Project Atlas RBRP River Basin Restoration Priorities ROW Right-of-Way RTE Rare, Threatened, or Endangered RWP Regional Watershed Plan ii WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN ACRONYMS PHASE 1: PRELIMINARY FINDINGS REPORT S&EC Sediment and Erosion Control SNHA Significant Natural Heritage Area SWCD Soil and Water Conservation District TAC Technical Advisory Committee TIP Transportation Improvement Program TLC Triangle Land Conservancy UDO Unified Development Ordinance USFWS United States Fish and Wildlife Service USGS United States Geological Survey UT Unnamed Tributary WAR Watershed Assessment Report WAT Watershed Assessment Team WMP Watershed Management Plan WRC Wildlife Resources Commission WSW Water Supply Watershed WWTP Waste Water Treatment Plant iii WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN CONTENTS PHASE 1: PRELIMINARY FINDINGS REPORT Table of Contents 1 INTRODUCTION 1 1.1 Purpose of Assessment 1 1.2 Description of Local Watershed Planning Area 2 1.3 Approach 6 2 LWP STUDY AREA FEATURES 9 2.1 Geographic Location and Description 9 2.2 Topography, Ecoregions, and Related Features 9 2.3 Previous Studies 9 2.4 Watershed History 10 3 LOCAL REGULATIONS AND PLANNING 12 3.1 Wake County 12 3.2 Johnston County 14 3.3 Town of Knightdale 14 3.4 Town of Wendell 15 3.5 Town of Zebulon 16 3.6 City of Raleigh 16 3.7 State of North Carolina 17 4 SUBWATERSHED DELINEATION 18 5 PRELIMINARY CHARACTERIZATION AND FUNCTIONAL ASSESSMENT 21 5.1 Watershed Characterization 21 5.1.1 Land Use and Cover 21 5.1.2 Watershed Impervious Surface Area 223 5.1.3 Hydric Soils, Hydrology, and Wetlands 24 5.1.4 Riparian Buffers, Riparian Zone Condition, and Floodplain Disturbance 267 5.1.5 Channel Condition 30 5.1.6 Preliminary Field Assessment 30 5.1.7 Water Quality and Biological Data 40 iv WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN CONTENTS PHASE 1: PRELIMINARY FINDINGS REPORT 5.2 PRELIMINARY IDENTIFICATION OF PROBLEMS & ASSETS 45 5.2.1 Stressors (Preliminary Functional Assessment Maps) 45 5.2.2 Assets (Preliminary Functional Assessment Maps) 51 6 RECOMMENDATIONS FOR FUTURE ASSESSMENT 523 6.1 Data Gaps 53 6.2 Objectives and Focus Areas for Future Study 55 6.3 Recommended Assessment Approach 56 6.4 Modeling 57 6.5 General Recommendations 58 7 RESTORATION AND PROTECTION OPPORTUNITIES 61 7.1 Degraded Buffer Opportunities 61 7.2 Stream Opportunities 66 7.3 Wetland Opportunities 70 7.4 BMP Opportunities 74 References 76 Appendix A. Existing Water Quality Data Summary 80 Appendix B. Benthic Macroinvertebrate Water Quality Investigation 147 Appendix C. Glossary of Terms 165 List of Figures Figure 1. Local Watershed Planning Area. ...................................................................................................................... 3 Figure 2. EEP Phase I Local Watershed Planning Process. ........................................................................................ 6 Figure 3. Digital Elevation Model of the LWP Study Area. ...................................................................................... 19 Figure 4. Subwatershed Delineations. ........................................................................................................................... 20 Figure 5. Land Cover in the Wake-Johnston Collaborative LWP Area. .............................................................. 22 Figure 6. Impervious Surface. ........................................................................................................................................... 23 Figure 7. Hydric Soils. .......................................................................................................................................................... 25 Figure 8. Streams and Wetlands. ..................................................................................................................................... 26 Figures 9a – 9d. Comparison of Subwatersheds based on Extent of Denuded Buffers. ............................... 28 Figure 10. Comparison of Percentage of Floodplain Disturbance....................................................................... 29 v WAKE-JOHNSTON COLLABORATIVE LOCAL WATERSHED PLAN CONTENTS PHASE 1: PRELIMINARY FINDINGS REPORT Figure 11. Example of Field Reconnaissance Form used for Windshield Surveys. ....................................... 31 Figure 12. Beddingfield Creek at Shotwell Road. ...................................................................................................... 32 Figure 13. Marks Creek. ......................................................................................................................................................... 33 Figure 14. Lower Buffalo Creek, (a) Upstream and (b) Downstream ................................................................ 34 Figure 15. Little River. ............................................................................................................................................................ 35 Figure 16. Snipe Creek, (a) Downstream and (b) Riparian Zone showing clear-cutting. .................................... 36 Figure 17. Rocky Branch. ....................................................................................................................................................... 37 Figure 18. Hominy Creek. ...................................................................................................................................................... 38 Figure 19. Upper Buffalo Creek. .......................................................................................................................................... 39 Figure 20. Impaired Streams from the 2010 303(d) List. ............................................................................................. 40 Figure 21. High Priority Subwatersheds for Hydrologic Issues ........................................................................... 46 Figure 22. High Priority Subwatersheds for Erosion and Sedimentation Issues........................................... 47 Figure 23. High Priority Subwatersheds for Stormwater Issues. ........................................................................ 48 Figure 24. High Priority Subwatersheds for Agricultural Issues. ........................................................................ 49 Figure 25. High Priority Subwatersheds for Water Quality Issues. .................................................................... 50 Figure 26. High Priority Subwatersheds for Rare Species. ...................................................................................