DRAFT Cape Fear River Basin Water Supply Plan NC Department of Environment and Natural Resources March 2009 Draft CFRB – WSP March 2009 TABLE OF CONTENTS Executive Summary .......................................................................................................................... 4 1 Existing Water Resources and Water Balances ....................................................................12 1.1 Basin Summary ............................................................................................................. 12 (a) Basin Description .................................................................................................... 12 (b) Major Flow Modification .......................................................................................... 13 1.2 Hydrology ...................................................................................................................... 15 (a) Surface Water ......................................................................................................... 15 (i) Surface water Availability and Reliability ................................................................ 15 (ii) Basin Model Description and Assumptions ............................................................ 22 (b) Ground Water ......................................................................................................... 51 (c) Instream Flow ......................................................................................................... 63 (i) Instream and Offstream Water Use ........................................................................ 63 (ii) Quantifying Instream Flow Needs........................................................................... 64 (iii) Maintaining Ecological Integrity .............................................................................. 68 (iv) The Existing Review Process for Instream Flows .................................................. 69 (v) Incorporating Instream Flow Needs in Basinwide Modeling and Planning ............ 69 1.3 Climatology .................................................................................................................... 75 (a) Precipitation ............................................................................................................ 75 (b) Temperature ........................................................................................................... 78 1.4 Water Quality ................................................................................................................. 79 2 Water Management ...............................................................................................................80 2.1 Drought Response Plan and Implementations ............................................................. 80 2.2 Interbasin Transfer ........................................................................................................ 85 2.3 Data Management Needs ............................................................................................. 88 References: ....................................................................................................................................90 Appendices .....................................................................................................................................92 1. County Summary…………………………………………………………………………………3 (a) Demographics……………………..……………………………………………………...4 (b) Local Water Supply Plans, County Populations and Growth Trends……………….5 2. Basin Specific Issues………………………………..………………………………………….17 (a) FERC – Hydropower……………………………….………………...……………….…17 (b) The Use of Water Supply on Jordan Lake…………………………………….………20 3. Instream Flow Needs……………………………………………………………………………21 4. Drought …………………………………………………………………………………………...30 5. Ground Water……………………………………………………………...……….……………40 6. Interbasin Transfer………………………………………………………………………………58 i Draft CFRB – WSP March 2009 LIST OF TABLES Table - 1: Cape Fear River Basin HUs .......................................................................................... 12 Table - 2: Cape Fear Water Supply Reservoirs ........................................................................... 14 Table - 3: Cape Fear Lock and Dam ............................................................................................. 14 Table - 4: List of USGS Unregulated Streamflow Gage Stations ................................................. 15 Table - 5: Randleman Lake Releases ........................................................................................... 28 Table - 6: Demands and Discharges Assumed in the Modeling (All units are in MGD) ............... 29 Table - 7: Water Supply Demand Deficits Predicted by the OASIS Model ................................... 34 Table - 8: System Inflows Reduced to 80% of Historical Natural Inflows Under 2050 demands .. 35 Table - 9: Jordan Lake Reservoir Operating Rules during Drought .............................................. 37 Table - 10: Jordan Lake Allocation (all units in MGD) ................................................................... 40 Table - 11: County Summary of Cape Fear River Basin Wells .................................................... 58 Table - 12: Modified Tennant Method Guidelines for Preliminary Screening of Instream Flow Concerns ....................................................................................................................................... 70 Table - 13: Stream Condition: Middle Deep River (Node 280) ..................................................... 72 Table - 14: Stream Condition: Middle Deep River (Node 280) ..................................................... 73 Table - 15: Stream Condition: Middle Deep River (Node 280) ..................................................... 74 Table - 16: Water Shortage Response Plan Data ......................................................................... 82 ii Draft CFRB – WSP March 2009 LIST OF FIGURES Figure - 1: Map of Cape Fear River Basin HUs ............................................................................. 13 Figure - 2: Map of 6 USGS Unregulated Streamflow Gage Stations ............................................ 15 Figure - 3: Monthly Mean Flow in Cubic Feet per Second ........................................................... 16 Figure - 4: Monthly Maximum Stream Flow in Cubic Feet per Second ........................................ 17 Figure - 5: Monthly Minimum Stream Flow in Cubic Feet per Second ......................................... 17 Figure - 6: Unit Mean Flow Statistics in Cubic Feet per Second / Square Mile of Drainage Area 18 Figure - 7: Unit Maximum Flow Statistics ...................................................................................... 19 Figure - 8: Unit Minimum Flow Statistics ....................................................................................... 19 Figure - 9: Flow Duration Plots for Period of Record – Log Scale ................................................ 20 Figure - 10: Flow Duration Plots for Period of Record................................................................... 21 Figure - 11: Cape Fear Hydrologic Model Schematic .................................................................. 24 Figure - 12: Cape Fear Hydrologic Model Detailed Schematic .................................................... 25 Figure - 13: Jordan Lake Storage Volume .................................................................................... 36 Figure - 14: Jordan Lake Elevation Profile .................................................................................... 39 Figure - 15: Jordan Lake Water Supply Pool Profile – Demands Scenarios ................................ 42 Figure - 16: Jordan Lake Water Supply Pool Profile – 100 MGD Scenario .................................. 43 Figure - 17: Jordan Lake Water Supply Pool Profile – 80% Inflows ............................................. 44 Figure - 18: Jordan Lake Water Quality Pool Profile – Demands Scenarios ............................... 46 Figure - 19: Jordan Lake Water Quality Pool Profile – 100 MGD Water Supply Demand ............ 47 Figure - 20: Jordan Lake Water Quality Pool Profile – 80% Inflow ............................................... 48 Figure - 21: Jordan Lake Boating Impacts ................................................................................... 50 Figure - 22: Hydrogeologic Cross Sections in CFRB (vertically exaggerated) ............................ 54 Figure - 23: Typical Water Budgets for the (a)Coastal Plain and (b)Piedmont Portions of CFRB 55 Figure - 24 Upper CFRB with and without Heath (1994) Recharge Rates ................................... 62 Figure - 25: Instream Flow Study Sites in the Cape Fear River Basin, NC................................... 67 Figure - 26: Stream Condition Middle Deep River, Dec-Feb ......................................................... 72 Figure - 27: Stream Condition Middle Deep River, March-May .................................................... 73 Figure - 28: Stream Condition Deep River, Jun-Nov ..................................................................... 74 Figure - 29: Map of Five SERCC Weather Stations ...................................................................... 76 Figure - 30: Average Annual Precipitation ..................................................................................... 77 Figure - 31: Average Monthly Rainfall ..........................................................................................