Waiokamilo September 2008 PR-2008-04
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Instream Flow Standard Assessment Report Island of Maui Hydrologic Unit 6055 Waiokamilo September 2008 PR-2008-04 State of Hawaii Department of Land and Natural Resources Commission on Water Resource Management COVER Waiokamilo Stream meets the Pacific Ocean in the terminal Waiokilo Falls in the lower section of the photo. The hydrologic unit spans from Pauwalu Point (top center), with Mokumana Islet just offshore, to the midway point between Waiokilo Falls and the mouth of Wailuanui Stream (not shown) [Google Earth, 2008]. Note: This report is intended for both print and electronic dissemination and does not include diacritical marks in spelling of Hawaiian words, names, and place names due to problems associated with its use electronically. However, Commission staff has made attempts to include diacritical marks in direct quotations to preserve accuracy. Table of Contents 1.0 Introduction......................................................................................................... 1 General Overview ...................................................................................................................................1 Current Instream Flow Standard...........................................................................................................1 Instream Flow Standards.......................................................................................................................1 Interim Instream Flow Standard Process.............................................................................................2 Instream Flow Standard Assessment Report......................................................................................3 Surface Water Hydrologic Units............................................................................................................4 Surface Water Definitions ......................................................................................................................4 2.0 Unit Characteristics.......................................................................................... 11 Geology..................................................................................................................................................11 Soils .......................................................................................................................................................11 Rainfall ...................................................................................................................................................12 Solar Radiation .....................................................................................................................................14 Evaporation ...........................................................................................................................................14 Land Use................................................................................................................................................15 Land Cover ............................................................................................................................................15 Flood ......................................................................................................................................................17 Drought ..................................................................................................................................................17 3.0 Hydrology.......................................................................................................... 25 Streams in Hawaii .................................................................................................................................25 Ground Water........................................................................................................................................27 Streamflow Characteristics .................................................................................................................29 Long-Term Trends in Flow...................................................................................................................32 4.0 Maintenance of Fish and Wildlife Habitat....................................................... 36 5.0 Outdoor Recreational Activities...................................................................... 45 6.0 Maintenance of Ecosystems............................................................................ 49 7.0 Aesthetic Values............................................................................................... 57 8.0 Navigation ......................................................................................................... 59 9.0 Instream Hydropower Generation................................................................... 60 10.0 Maintenance of Water Quality ......................................................................... 61 11.0 Conveyance of Irrigation and Domestic Water Supplies .............................. 66 12.0 Protection of Traditional and Customary Hawaiian Rights........................... 68 13.0 Noninstream Uses ............................................................................................ 91 14.0 Bibliography.................................................................................................... 148 15.0 Appendices ..................................................................................................... 159 i List of Figures Figure 1-1. Information to consider in setting measurable instream flow standards......................................................2 Figure 1-2. Simplified representation of the interim instream flow standard and permanent instream flow standard processes. Keys steps of the adopted interim IFS process are depicted in the left column by the boxes drawn with dotted lines.......................................................................................3 Figure 1-3. Topographic map of the Waiokamilo hydrologic unit in east Maui, Hawaii (Source: U.S. Geological Survey, 1996).................................................................................................................................7 Figure 1-4. Elevation range and the location of Waiokamilo hydrologic unit. (Source: State of Hawaii, Office of Planning, 1983).....................................................................................................................8 Figure 1-5. Major and minor roads and Tax Map Key (TMK) parcel boundaries for Waiokamilo hydrologic unit (Source: County of Maui, 2006; County of Maui, Geographic Information Systems [GIS] Division, Department of Management, 2006)...........................................................................9 Figure 1-6. Quickbird satellite imagery of Waiokamilo hydrologic unit (Source: County of Maui, Planning Department, 2004). .........................................................................................................................10 Figure 2-1. Orographic precipitation in the presence of mountains higher than 6,000 feet. ........................................13 Figure 2-2. Generalized geology of Waiokamilo hydrologic unit (Source: Sherrod et al., 2007; State of Hawaii, Office of Planning, 2006a; and State of Hawaii, Commission on Water Resource Management, 2008c).....................................................................................................................19 Figure 2-3. Soil classification in Waiokamilo hydrologic unit (Source: State of Hawaii, Office of Planning, 2007c)............................................................................................................................................20 Figure 2-4. Mean annual rainfall and fog area in Waiokamilo; and solar radiation for Waiokamilo and the island of Maui, Hawaii (Source: Giambelluca et al., 1986; State of Hawaii, Office of Planning, 2006b; 2006c). ...........................................................................................................................21 Figure 2-5. State land use district boundaries in Waiokamilo hydrologic unit (Source: State of Hawaii, Office of Planning, 2006d).................................................................................................................22 Figure 2-6. C-CAP land cover in Waiokamilo hydrologic unit (Source: National Oceanic and Atmospheric Administration, Coastal Services Center, 2000)........................................................................23 Figure 2-7. Hawaii GAP land cover classes in Waiokamilo hydrologic unit (Source: Hawaii GAP Analysis Program, 2005)................................................................................................................................24 Figure 3-1. a) Dam #3 on Waiokamilo Stream; b) losing reach immediately downstream of dam #3 on Waiokamilo Stream; c) Waiokamilo Stream upstream of dam #3; and d) losing reach upstream of dam #3.......................................................................................................................................26 Figure 3-2. Diagram illustrating the ground water system east of Keanae Valley, northeast Maui, Hawaii. Arrows indicate general direction of ground water flow (Source: Gingerich, 1999b)............................................................................................................................................................28 Figure 3-3. Aquifer system area and well locations in Waiokamilo hydrologic