Opinion ID: 2629221
Heading Depth: 3
Heading Rank: 3

Heading: Moloka'i's hydrology and the proposed well site

Text: Virtually the entire island of Moloka'i rests atop fresh groundwater, which results from water seeping into the soil and being stored in highly permeable volcanic basalt rock. Moloka'i depends on high-level groundwater and basal groundwater [11] for its water supply. Within the rift zones of the East Moloka'i Volcano, fresh groundwater is impounded to high levels in the volcanic rocks between low-permeability dikes. Within the flank lava flows of the island, a freshwater lens floats on the denser, underlying saltwater; the intermediate transition zone composed of brackish water rests between the freshwater and saltwater. [12] The freshwater lens consists of groundwater recharge from (1) upgradient high-level groundwater areas, (2) infiltration of rainfall, and (3) irrigation water. The thickness of the freshwater lens increases with (1) increasing rates of groundwater recharge, (2) decreasing rates of withdrawal, and (3) decreasing aquifer permeability. Moloka'i is composed of four hydrologic units: the West, Central, Northeast, and Southeast sectors. The four hydrologic units have been subdivided into sixteen aquifer systems. The Kualapu'u aquifer system is located in the Central sector, and the Kamiloloa aquifer system (Wai'ola's proposed well site) is located in the Southeast sector, adjacent to and east of the Kualapu'u aquifer system. Presently, four wells tap into the Kualapu'u aquifer system to pump drinking water for the County, DHHL, and KMI. The sustainable yield, see infra note 25, of the Kamiloloa aquifer system is 3.0 mgd; the existing water allocations in the Kamiloloa aquifer system total 0.211 mgd with no reservations for future water uses. In addition to high-level groundwater and basal groundwater, the Moloka'i Irrigation System (MIS) provides another water source to the island. The MIS receives water from three wells that tap into the Waikolu aquifer system, which is located in the northeast sector and adjacent to the Kamiloloa aquifer system. The proposed well in the Kamiloloa aquifer system, however, is separate from the dike compartments in the Waikolu valley and, therefore, would not diminish the water sources available to the MIS.