[en] This report describes the field investigation of groundwater discharging from the 100-D/DR Reactor Area into the Hanford Reach of the Columbia River located in Richland, Washington. This section of the Reach is used by fall chinook salmon as spawning habitat. The field investigation focused on hexavalent chromium in river substrate pore water, river water, riverbank seepage, and the Hanford Site aquifer at the shoreline. These data are used to establish a baseline for chromium concentrations in river substrate pore water and in the aquifer. This baseline will help assess the potential for exposure of ecological receptors to contaminated groundwater discharges and support groundwater remediation services. This groundwater is contaminated with hexavalent chromium at concentrations that exceed the U.S. Environmental Protection Agency's chronic ambient water quality criterion