The Rosemont Copper Project is a proposed open-pit mine located in Pima County, Arizona, with an estimated operational life of 20-25 years. Copper, and to a lesser extent molybdenum and silver are the metals of interest. During this project, approximately 546 million tons (Mt) of sulfide ore and approximately 70 Mt of oxide ore will be processed. In this process, approximately 1,232 Mt of waste rock will be produced (Tetra Tech, 2012a). The site selected for the mine resides within a sensitive region of the Santa Cruz watershed, near headwaters for tributaries. Furthermore, the Cienega Creek and Davidson Canyon are natural preserves that supply water to the Tucson Basin and host several species, such as aquatic and riparian plants and animals (Powell et al., 2014). Past mining operations in Arizona were always associated with negative impacts on the environment, both during mining and post-mining (Earthworks, 2012), with acid mine drainage and airborne particles from smelter emissions and wind erosion of mine tailings. In addition, potential human-health risks are associated with these impacts. Modern mine development requires a robust assessment of environmental and human-health impacts. The goal of this work is to identify contaminant sources and contaminants of concern, as well as to delineate their potential release mechanisms and transport pathways.