Metals enter Little Cottonwood Creek in Salt Lake County, Utah, in drainage water that discharges from inactive mines in the watershed (fig. 1). As part of a study to evaluate the effects of this mine drainage on water quality, a sodium chloride tracer was injected into Little Cottonwood Creek during September 17-18, 1998. The purpose of the injection was to quantify stream discharge; to identify inflows, both those observable and those dispersed in the subsurface; and ultimately, to determine which areas within the watershed contribute the most metals to Little Cottonwood Creek. The purpose of this report is to make these data available to agencies responsible for managing the area’ s water resources and to supplement interpretive reports for this study.