HAWAII COUNTY WATER USE AND DEVELOPMENT PLAN UPDATE Hawaii Water Plan Keauhou Aquifer System Funded by the: March 2017 Department of Water Supply For the: County of Hawaii FUKUNAGA & ASSOCIATES, INC. Final Report Consulting Engineers 1357 Kapiolani Boulevard, Suite 1530 Honolulu, Hawaii 96814 • (808) 944-1821 Table of Contents TABLE OF CONTENTS LIST OF ABBREVIATIONS ............................................................................................ viii CHAPTER 1 Introduction ................................................................................................... 1-1 CHAPTER 2 Technical Approach ...................................................................................... 2-1 2.1 WATER RESOURCES PLANNING METHODOLOGY ......................................... 2-1 2.1.1 Existing Sources and Water Uses ................................................................... 2-1 2.1.1.1 Ground Water Pumpage ................................................................... 2-2 2.1.1.2 Municipal Water Meter Records ...................................................... 2-3 2.1.1.3 Water Use Unit Rates ....................................................................... 2-3 2.1.1.4 Other Water Resources ..................................................................... 2-4 2.1.2 Anticipated Water Demands ........................................................................... 2-4 2.1.2.1 Water Demand for Existing Developed Parcels (Pumpage) ............. 2-5 2.1.2.2 Water Entitlements ........................................................................... 2-5 2.1.2.3 Community Development Plans ....................................................... 2-5 2.1.2.3.1Kona Community Development Plan ................................. 2-6 2.1.2.3.2Kona CDP Financing Plan .................................................. 2-6 2.1.3 Hawai‘i County Zoning Water Demands ........................................................ 2-9 2.1.3.1 Water Demand for Existing Developed Parcels (Pumpage) ........... 2-10 2.1.3.2 Updated Zoning of Undeveloped Parcels ....................................... 2-10 2.1.3.3 Agricultural Water Use Demands ................................................... 2-10 2.1.4 Additional Information Used to Refine Land Use Based Water Demands .. 2-11 2.1.4.1 State Water Projects Plan Updates and DHHL Demands .............. 2-11 2.1.4.2 Other Development Plans ............................................................... 2-12 2.1.5 5-Year Incremental Water Demand Projections ........................................... 2-12 2.1.5.1 Population and Growth Rate Projections ........................................ 2-19 2.1.5.2 Historical Ground Water Use and Population ................................ 2-19 CHAPTER 3 Water Demand Scenarios and Projections ................................................. 3-1 3.1 KEAUHOU AQUIFER SYSTEM AREA PROFILE ................................................. 3-1 3.1.1 General ............................................................................................................ 3-1 3.1.2 Economy and Population ................................................................................ 3-1 3.1.2.1 Economy ........................................................................................... 3-1 3.1.2.2 Population ......................................................................................... 3-1 3.1.3 Land Use ......................................................................................................... 3-2 3.1.3.1 Anticipated Water Demands ............................................................. 3-2 3.1.3.2 Hawai‘i County Zoning Water Demand ........................................... 3-2 3.2 EXISTING WATER RESOURCES ........................................................................... 3-7 3.2.1 Ground Water .................................................................................................. 3-7 3.2.2 Surface Water .................................................................................................. 3-8 3.2.3 Rainwater Catchment ...................................................................................... 3-8 3.2.4 Recycled Water ............................................................................................... 3-8 3.3 EXISTING WATER USE......................................................................................... 3-13 Hawai‘i Water Use and Development Plan Update iii Keauhou Aquifer System Table of Contents 3.3.1 General .......................................................................................................... 3-13 3.3.2 Domestic Use ................................................................................................ 3-14 3.3.3 Industrial Use ................................................................................................ 3-14 3.3.4 Irrigation Use ................................................................................................ 3-14 3.3.5 Agricultural Use ............................................................................................ 3-15 3.3.6 Military Use .................................................................................................. 3-15 3.3.7 Municipal Use ............................................................................................... 3-15 3.3.7.1 County Water Systems ................................................................... 3-15 3.3.7.2 State Water Systems ....................................................................... 3-17 3.3.7.3 Federal Water Systems ................................................................... 3-17 3.3.7.4 Private Public Water Systems ......................................................... 3-17 3.3.8 Water Use by Resource ................................................................................. 3-17 3.3.8.1 Ground Water ................................................................................. 3-17 3.3.8.2 Surface Water ................................................................................. 3-18 3.3.8.3 Rainwater Catchment ...................................................................... 3-18 3.3.8.4 Recycled Water ............................................................................... 3-18 3.4 FUTURE WATER NEEDS ...................................................................................... 3-18 3.4.1 General .......................................................................................................... 3-18 3.4.2 Anticipated Water Demands ......................................................................... 3-19 3.4.3 Hawai‘i County Zoning Water Demands ...................................................... 3-23 3.4.3.1 Agricultural Water Demands .......................................................... 3-23 3.4.4 5-Year Incremental Water Demand Projection ............................................. 3-23 CHAPTER 4 Resource and Facility Strategies .................................................................. 4-1 4.1 OVERVIEW AND WATER SOURCE ADEQUACY .............................................. 4-1 4.2 HDWS FACILITY IMPROVEMENT PROGRAM ................................................... 4-1 4.2.1 History and Objectives .................................................................................... 4-1 4.2.2 Implementation of HDWS Long Range Master Plan ..................................... 4-2 4.2.3 HDWS Capital Improvement Program ........................................................... 4-5 4.3 CONCEPTUAL SOURCE DEVELOPMENT STRATEGIES .................................. 4-5 4.3.1 Source Development Program ........................................................................ 4-5 4.3.1.1 Ground Water ................................................................................... 4-5 4.3.1.2 Source Conveyance and Storage ...................................................... 4-9 4.3.2 Non-Potable Source Strategies ........................................................................ 4-9 4.3.2.1 Surface Water ................................................................................... 4-9 4.3.2.2 Recycled Water ................................................................................. 4-9 4.3.2.3 Rainwater ........................................................................................ 4-13 4.3.2.4 Desalination .................................................................................... 4-13 4.3.3 Other Resource Enhancement Measures ....................................................... 4-13 4.3.3.1 Water Conservation ........................................................................ 4-13 4.4 MEETING ANTICIPATED DEMANDS ................................................................ 4-14 4.5 IMPLEMENTATION PLAN ................................................................................... 4-18 4.5.1 Near-Term ..................................................................................................... 4-18 4.5.2 Medium-Term and Long-Term ..................................................................... 4-19 CHAPTER 5 Environmental and Cultural Issues & Public Consultation ..................... 5-1 5.1 PRELIMINARY T&C RESEARCH .......................................................................... 5-1 iv Hawai‘i Water Use and Development Plan Update Keauhou Aquifer System Table of Contents 5.2 INITIAL OUTREACH ..............................................................................................