Groundwater Availability in the Haiku, Honopou, and Makawao Areas, Northeast Maui, Hawaii
Phase 2 -- Evaluation of the Connection between Groundwater and Surface Water and Understanding Regional Hydrology
Project Chief: Stephen B. Gingerich
Project Period: June 2013 through September 2015
Cooperator: Maui County Department of Water Supply
Location: Island of Maui
Demand for water from the Upcountry area of Maui is expected to increase in the future, with the Haiku, Honopou, and Makawao Aquifer Systems being potential source areas for meeting this demand.
However, there is concern about the effects of additional groundwater development on streamflow and on existing wells in the area.
Development of additional water supply from parts of the Haiku Aquifer System is subject to compliance with the East Maui Water Development Plan Consent Decree.
One of the items stipulated in the Consent Decree that must be addressed is an evaluation of the effects of groundwater withdrawal on streamflow.
This evaluation must include collection of additional data to determine whether the groundwater system has a perched aquifer above a typical Hawaiian freshwater lens system or is fully saturated to several hundred feet above sea level.
The nature of the high-level groundwater body has important implications for understanding the potential interaction between groundwater and surface water and how groundwater withdrawals may affect streamflow.
Furthermore, hydrologic data such as water levels and aquifer hydraulic conductivity estimates are limited to only a few locations in the study area; therefore, more data are needed to evaluate the hydrologic conditions of the entire study area.
The objective of this phase (Phase 2) of the overall study is to evaluate the potential connection between groundwater and surface water within the study area.
This phase includes the selection of a site for new exploratory wells and a testing and monitoring plan designed to provide information to evaluate whether the high-level groundwater body is perched or fully saturated.
Additionally, collection of groundwater-level and salinity data across the study area will provide a better understanding of the regional hydrologic conditions and help evaluate the effects of additional pumping on existing wells.
The Phase 1 part of the study is to estimate the spatial distribution of groundwater recharge for the Haiku, Honopou, and Makawao Aquifer Systems.
The last phase of the study (Phase 3) will use a numerical groundwater model to evaluate the effects of additional withdrawals on streamflow, coastal discharge, and salinities in existing wells in the study area.
Relevance and Benefits
The results from this study are necessary to properly manage groundwater in the State of Hawaii.
The study is consistent with the USGS Science Strategy to provide citizens, communities, natural-resource managers, and policymakers with a clearer knowledge of the status of their water resources.
To meet the objectives of this phase (Phase 2) of the overall study, the approach is separated into two work elements:
1) collect water-level data and salinity to improve the understanding of the hydrologic conditions of the Haiku, Honopou, and Makawao Aquifer Systems and
2) implement a testing and monitoring plan for a pair of exploratory wells designed to provide information about the nature of high-level groundwater in the study area.
Results from this study will be published in the USGS Scientific Investigations Report series and made available on the internet.
A reconnaissance survey was conducted to identify wells for collecting water-level data needed to refine the conceptual model of the groundwater-flow system.
Each well was surveyed to a common datum using differential Global Positioning System technology and first order leveling techniques.
This study has been temporarily suspended.