Altitudes of well measuring points surveyed during 2023–24, Hālawa area, O‘ahu, Hawai‘i

This data release contains a comma-delimited file of 71 well measuring-point altitudes for monitored wells in the Hālawa area, O‘ahu, Hawai‘i. The measuring-point altitude of a monitoring well is needed to determine the groundwater level in the well relative to a datum such as local mean sea level. A well measuring point is typically located at the top of the well casing. By surveying well measuring-point altitudes to a common datum and accuracy standard, groundwater levels measured in monitoring wells can be reliably compared. The common datum used for this survey is local mean sea level for the National Tidal Datum Epoch 1983–2001 as determined by the National Oceanic and Atmospheric Administration, National Ocean Service, Center for Operational Oceanographic Products and Services, in December 2017. For this dataset, well measuring-point altitudes were surveyed using geodetic leveling methods with second-order, class I vertical-accuracy standards, consistent with the accuracy to which the local survey marks were surveyed. A digital level with a rated accuracy of 0.3 millimeters and invar leveling rods were used for the survey. Measuring-point altitudes of surveyed wells ranged from 24.46 to 766.12 feet above local mean sea level.