Watershed Management Plan
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Kohala Mountain Watershed Management Plan DRAFT December 2007 Kohala Mountain Watershed Management Plan TABLE OF CONTENTS EXECUTIVE SUMMARY .................................................................................................. 3 I. INTRODUCTION ......................................................................................................... 8 II. DESCRIPTION AND CURRENT CONDITION OF KOHALA WATERSHED............................... 10 A. Physical Characteristics ............................................................................ 12 B. Hydrology and Water Use ......................................................................... 12 C. Biological Resources ................................................................................. 24 1. Ecosystems ..................................................................................... 24 2. Species Biodiversity ........................................................................ 27 D. Socio-Cultural Resources .......................................................................... 34 1. Land Ownership, Land Use Zones, and Land Management ........... 34 2. Population and Local Communities ................................................. 43 3. Cultural Resources and Traditional Practices ................................. 43 4. Compatible Public Uses .................................................................. 45 5. Infrastructure and Facilities ............................................................. 46 III. WATERSHED VALUES ............................................................................................. 48 A. Water Resources ....................................................................................... 48 B. Watershed Functions of Forest .................................................................. 48 C. Native Species and Ecosystems ............................................................... 49 D. Cultural Resources .................................................................................... 50 E. Public Access and Outdoor Recreation ...................................................... 51 IV. THREATS TO THE KOHALA WATERSHED ................................................................... 53 A. Invasive Plant Species .............................................................................. 53 B. Feral Ungulates ......................................................................................... 54 C. Other Non-Native Animals ......................................................................... 56 D. Human Activities ........................................................................................ 58 E. Aquatic Pollutants ...................................................................................... 58 F. Wildfire ....................................................................................................... 60 G. Climate Change ........................................................................................ 60 V. MANAGEMENT PROGRAM ......................................................................................... 61 1. Protect Water Resources............................................................................ 62 2. Control Invasive Plant Species .................................................................. 66 3. Control Non-Native Animals ....................................................................... 71 4. Biodiversity Protection ............................................................................... 75 5. Wildfire Management ................................................................................. 78 6. Promote Compatible Public Use ................................................................ 78 7. Infrastructure and Administrative Coordination .......................................... 82 VI. MANAGEMENT PROGRAM INDICATORS ..................................................................... 84 VII. BIBLIOGRAPHY....................................................................................................... 86 DRAFT December 2007 -- Kohala Mountain Watershed Management Plan 1 APPENDICES ........................................................................................................... 96 A. Partial List of Plants and Animals of Kohala Mountain Watershed ............. 97 B. Selected Hawai‘i Revised Statutes and Administrative Rules .................... 111 C. Summaries of Earlier Planning and Management Efforts .......................... 115 D. Proposed Biodiversity Conservation Units ................................................ 122 LIST OF FIGURES 1. Land Ownership ....................................................................................... 11 2. Rainfall and Cloud Forest Distribution ..................................................... 14 3. Streams and Ditches ................................................................................ 19 4. Waimea Irrigation System ........................................................................ 21 5. Lower Hämäkua Irrigation System ........................................................... 22 6. County Zoning and State Land Use Districts ........................................... 36 7. Recreational Resources within the Kohala WMA .................................... 42 7. State Public Hunting Units ....................................................................... 42 7. Trails, Facilities and Infrastructure ........................................................... 42 8. Watershed Management Areas ............................................................... 64 9. Existing Fenced Units within Area ............................................................ 76 LIST OF TABLES 1. Major Streams Emanating from the Kohala WMA .................................... 16 2. Current Water Usage from Kohala Mountain ........................................... 23 3. Acreage of Parcels with the WMA ............................................................ 34 DRAFT December 2007 -- Kohala Mountain Watershed Management Plan 2 Kohala Mountain Watershed Management Plan EXECUTIVE SUMMARY On the island of Hawai‘i, Kohala Mountain, crowned in native cloud forest, lies perpendicular to the prevailing trade winds, favoring frequent cloud formation and abundant rainfall vital to North Hawai‘i. These forested areas of Kohala Mountain are vital for recharge of North Hawai‘i’s groundwater aquifers and a supply of dependable surface water for its streams. As described in Chapter I, the Kohala Watershed Partnership (KWP) brings together major landowners on Kohala Mountain to protect the water resources and watershed functions of the forested watershed. Efforts to protect vital watershed values began to coalesce when a group of government and private landowners signed a Memorandum of Understanding (MOU) in August 2003, officially forming the Kohala Watershed Partnership. By signing this MOU, partners committed to work collaboratively to protect the Kohala Mountain Watershed, despite differences in priorities, mandates and constituencies. These partners include: Parker Ranch; Kahuä Ranch; Ponoholo Ranch; Kamehameha Schools; Queen Emma Foundation; Surety Kohala Corporation; Laupahoehoe Nui, LLC; Hawai‘i Department of Land and Natural Resources; and Department of Hawaiian Home Lands. The Hawai‘i County Department of Water Supply and The Nature Conservancy have joined in this effort as (non-landowner) “associate” partners, because of their experience in and commitment to effective watershed conservation. The primary goal of the Kohala Watershed Partnership is to show improvements in water and environmental quality by enabling comprehensive and sustainable watershed management projects that address the threats to the watershed, while maintaining its integrity and protecting its economic, socio-cultural, and ecological resources. This management plan describes the watershed resources and associated values, identifies the threats to those resources, and directs the activities of the KWP toward their protection. This plan sets management goals, identifies information needs, and prescribes monitoring activities to measure effectiveness and success. The area addressed by this plan includes approximately 68,000 Acres (Ac) of forest and grass lands on the windward and leeward slopes of the Kohala Volcano. Chapter II of the management plan describes the resources, uses, and current conditions of the Kohala Watershed, including physical characteristics, hydrology and water use, biological resources, and socio-cultural resources. Kohala Mountain provides approximately 6% (154 million gallons per day) of the sustainable yield of water for Hawai‘i Island, though potential production is far greater. Hawai‘i County Department of Water Supply (DWS) relies on the streams and groundwater of Kohala Mountain for its primary source of domestic drinking water for residents of North Kohala, South Kohala, and parts of Hämäkua. The Hawai‘i Department of Agriculture’s Waimea Irrigation Water System, the Kohala Ditch System, and the Lower Hämäkua Ditch Irrigation System depend on surface water from Kohala Mountain to provide agricultural irrigation water to farms. Private ranches, such as Parker Ranch, Ponoholo Ranch, and Kahuä Ranch also rely on the waters of Kohala. The taro farmers in Waipi‘o Valley also depend on a reliable source of water from the watershed. The Kohala watershed management area (WMA) is also rich in biological resources, unique ecosystems,