NATIONAL PARK SERVICE U.S. Department of the Interior Water Resources Division Technical Report NPS/NRWRD/NRTR-2006/359 Natural Resource Program Center National Park ServicU.S. Departmenthe Interior Natural Resource Program Centerent of the Interior ASSESSMENT OF COASTAL WATER RESOURCES AND WATERSHED CONDITIONS AT PU‘UKOHOLA HEIAU NATIONAL HISTORIC SITE, HAWAI‘I Dr. Daniel J. Hoover and Colette Gold The National Park Service Water Resources Division is responsible for providing water resources management policy and guidelines, planning, technical assistance, training, and operational support to units of the National Park System. Program areas include water rights, water resources planning, marine resource management, regulatory guidance and review, hydrology, water quality, watershed management, watershed studies, and aquatic ecology. Technical Reports The National Park Service disseminates the results of biological, physical, and social research through the Natural Resources Technical Report Series. Natural resources inventories and monitoring activities, scientific literature reviews, bibliographies, and proceedings of technical workshops and conferences are also disseminated through this series. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service. Copies of this report are available from the following: National Park Service (970) 225-3500 Water Resources Division 1201 Oak Ridge Drive, Suite 250 Fort Collins, CO 80525 National Park Service (303) 969-2130 Technical Information Center Denver Service Center P.O. Box 25287 Denver, CO 80225-0287 Cover photos: Top: NPS photo Left: Carolyn Stewart Right: Kristen Keteles Bottom: Daniel Hoover ii ASSESSMENT OF COASTAL WATER RESOURCES AND WATERSHED CONDITIONS AT PU‘UKOHOLA HEIAU NATIONAL HISTORIC SITE, HAWAI‘I Dr. Daniel J. Hoover Colette Gold Technical Report NPS/NRWRD/NRTR-2006/359 Department of Oceanography University of Hawai‘i at Manoa Honolulu, HI 96822 November 2006 This report was prepared under Task Order J2380040120 of the Hawai‘i-Pacific Islands Cooperative Ecosystems Study Support Unit (agreement H8080040012). iii iv ACRONYMS AND ABBREVIATIONS ..................................................................................2 EXECUTIVE SUMMARY.......................................................................................................4 A. INTRODUCTION..............................................................................................................12 B. SITE DESCRIPTION ........................................................................................................12 B.1. BACKGROUND ............................................................................................................12 B.1.a. Location, setting, and site holdings ....................................................................12 B.1.b. Land use ............................................................................................................14 B.1.c. Human utilization: historic and current .............................................................18 B.2. HYDROLOGIC INFORMATION .......................................................................................19 B.2.a. Oceanographic setting.......................................................................................19 B.2.b. Hydrology affecting the site ...............................................................................21 B.2.c. Water bodies and other water resources ............................................................27 B.2.c.i. Groundwater...............................................................................................27 B.2.c.ii. Anchialine habitat.......................................................................................27 B.2.c.iii. Wetlands ....................................................................................................28 B.2.c.iv. Rocky and sandy intertidal..........................................................................28 B.2.c.v. Coastal waters ............................................................................................29 B.2.c.vi. Kawaihae Harbor........................................................................................30 B.3. BIOLOGICAL RESOURCES.............................................................................................30 B.3.a. Freshwater ........................................................................................................30 B.3.b. Groundwater .....................................................................................................32 B.3.c. Anchialine habitat..............................................................................................32 B.3.d. Wetlands............................................................................................................32 B.3.e. Rocky and Sandy Intertidal ................................................................................35 B.3.f. Coastal Waters ..................................................................................................37 B.3.f.i. Planktonic and pelagic biological resources ................................................37 B.3.f.ii. Subtidal benthic resources ..........................................................................45 B.3.g. Kawaihae Harbor ..............................................................................................57 C. ASSESSMENT OF COASTAL WATER RESOURCES .................................................58 C.1. SOURCES OF POLLUTANTS ...........................................................................................58 C.1.a. Point and non-point sources ..............................................................................58 C.1.a.i. Surface runoff.............................................................................................58 C.1.a.ii. Groundwater contamination........................................................................58 C.1.a.ii. Herbicide use..............................................................................................59 C.1.a.iii. Garbage and animal waste ..........................................................................59 C.1.a.iv. Sedimentation.............................................................................................60 C.1.a.iii. Air, noise and light pollution ......................................................................61 C.1.a.iv. Kawaihae Harbor........................................................................................61 v C.2. ASSESSMENT OF BIOLOGICAL RESOURCES WITH RESPECT TO WATER QUALITY...............63 C.2.a. Water quality standards.....................................................................................63 C.2.a.i. Groundwater...............................................................................................65 C.2.a.ii. Anchialine/estuarine habitat........................................................................74 C.2.a.iii. Wetlands ....................................................................................................75 C.2.a.iv. Rocky and sandy intertidal..........................................................................75 C.2.a.v. Coastal waters ............................................................................................76 C.2.a.vi. Subtidal benthic resources ..........................................................................83 C.2.b. Ecosystem effects ...............................................................................................84 C.2.b.i. Groundwater/Anchialine Pools ...................................................................84 C.2.b.ii. Wetlands ....................................................................................................85 C.2.b.iii. Rocky and sandy intertidal..........................................................................86 C.2.b.iv. Coastal waters ............................................................................................86 C.2.c. Human health effects .........................................................................................87 C.2.c.i. Groundwater...............................................................................................87 C.2.c.ii. Anchialine pools.........................................................................................87 C.2.c.iii. Wetlands ....................................................................................................88 C.2.c.iv. Rocky and sandy intertidal..........................................................................88 C.2.c.v. Coastal waters ............................................................................................88 C.3. LIST OF IMPAIRMENTS .................................................................................................89 C.4. LIST OF WATER BODIES WITH UNDOCUMENTED CONDITIONS/STATUS ............................89 D. ISSUES AND THREATS TO COASTAL RESOURCES ................................................91 D.1. COASTAL DEVELOPMENT ............................................................................................91 D.1.a. Population and land use ....................................................................................91 D.1.b. Surface and groundwater withdrawals and inputs..............................................93 D.1.c. Erosion..............................................................................................................93