Seepage Runs of Hālawa Stream, Oʻahu, Hawaiʻi: December 2021 - June 2022

This data release contains four seepage runs conducted along selected reaches of South Hālawa Stream, North Hālawa Stream, and Hālawa Stream, Oʻahu, Hawaiʻi between December 2021 and June 2022. The data release has four child items that each consist of the following files: (1) a metadata xml file describing the child-item files and data attributes, (2) an annotated map showing the seepage-run measurement sites, and (3) a comma-delimited ascii data file with the discrete discharge measurements. These discrete discharge measurements form what is commonly referred to as a “seepage run.” The intent of these seepage runs was to quantify the spatial distribution of streamflow along the reach before and after the initiation of discharge of water from Red Hill Shaft into South Hālawa Stream on January 29, 2022. Two seepage runs were conducted before discharge activity commenced and two seepage runs were conducted during active discharging conditions. Discharge measurements were collected during fair-weather, low-flow conditions, generally characterized by negligible direct runoff within the reach. The measurements can be used to characterize the net seepage of water into (water gain) or out of (water loss) the stream channel between measurement sites provided that the measurements were made during stable, nonchanging flow conditions and external surface inflows (for example, a tributary) or outflows (for example, a diversion) of water to the reach are quantified and accounted for in the computation of net seepage.