India is one of the largest producers of chromium ore and salts, which are used worldwide as tanning agents (Dubeyetal. 2001). Following ore processing, extensive chromium slag is generated requiring disposal. Within the Indian state of Tamil Nadu, there exist numerous processing sites and tanneries where slag piles have accumulated. In one such site, the spent ore totals an estimated 1.5 million metric tons with the waste slag pile towering almost 12 m on a 3-ha footprint. The site occupies a gentle slope whereby rainwater flows to the Palar River which ultimately terminates at Chennai and the Bay of Bengal. Chromium ore slag can include commonly existing species of chromium including trivalent chromium (Cr(III)), hexavalent chromium (Cr(VI)), and elemental chromium (Cr). Although the adverse health effects of trivalent chromium are still widely debated, it is readily oxidized to the water-soluble and carcinogenic hexavalent chromium, which can contaminate surface and groundwater (US EPA 1998). The extent of hexavalent chromium contamination from chromate ores and tannery processing operations is well studied (Avudainayagam et al. 2003; Kumar and Riyazuddin 2010; Panda et al. 2012)