Sources of Surface Flow and Metal Exceedances in Davidson Canyon and Cienega Creek Watersheds

The Regional Flood Control District’s Cienega Creek Preserve is a jewel of Pima County, with ephemeral and perennial water that recharges groundwater, sustains riparian habitat, and attenuates flood flow upstream Tucson. Given ongoing drought effects and potential upstream land use changes, County leaders understood that protecting this resource requires better characterization of contributing watersheds. In 2017, District sought assistance of Dr. Jennifer McIntosh at UA and initiated funding for her students to undertake the necessary hydrogeochemical tracer and modeling research projects. These funded student projects determined that Davidson Canyon and Cienega Creek baseflows include older groundwater contributions and relative watershed contributions in this geologically complex area. Dr. McIntosh will present the latest dissertation results from dissolved metals concentrations that show new and increasing presence of lead, zinc, arsenic, and copper in both storm and baseflow in Davidson Canyon, which was unexpected and indicates a significant recent change in the system.

Dr. Jennifer McIntosh is a hydrogeochemist with research focuses on the elemental and isotopic chemistry of surface waters, groundwaters, saline fluids, and natural gas to understand processes throughout the earth’s crust. She is a UA Distinguished Scholar in Hydrology and Atmospheric Sciences Department. Adjunct Professor at University of Saskatchewan, and former USGS Adjunct Research Geologist (2007-2017). She’s also a fellow of GSA-CIFAR Advanced Research Earth 4D Subsurface Science Exploration Program. She received a BA in geology-chemistry from Whitman College, a PhD in geology from the University of Michigan, and a Postdoctoral Fellowship at Johns Hopkins University. She was named the inaugural recipient of the Dr. Thomas Meixner Endowed Professor in Hydrology & Atmospheric Sciences. Other notable awards include the UA Distinguished Scholar Award, USGS Star award, and Blitzer Award for teaching. She regularly serves as a technical expert for the US EPA, National Academies of Sciences and Engineering, and Nuclear Waste Technical Review Board.

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