Hydrologic Characterization of a Large Mining District Superfund Site in Colorado The Bonita Peak Mining District (BPMD) was added to the National Priorities List (NPL) in 2016. The BPMD consists of 48 historic mines or mining related features located within a highly mineralized caldera. These features have impacted water quality throughout the Animas River Watershed. This presentation will highlight the challenges associated with remediation at the BPMD including the data needs and approaches to acquire the data. One of the primary data needs is to develop an understanding of how surface and ground water is impacted by natural and anthropogenic sources of contamination. This effort is complicated by extensive faulting and fracturing, as well as numerous mine workings which exist in the area. Ian will discuss existing information obtained by years of investigation by many organizations including: local stakeholders, USGS, Colorado, EPA, and others. The data presented includes surface water quality and quantity, mining and geologic maps, groundwater/surface water interactions, and ecological impacts. Ian Bowen joined the U.S. Environmental Protection Agency in July 2015 after working for the U.S. Army Corps of Engineers for 5 years. During that time, he has worked on a wide variety of contaminated sites including organic and metal contamination in groundwater, surface water, and solid media. Ian obtained a M.Sc. in Geology from the University of Kansas where he assisted with development of a tool to directly measure groundwater velocity.