ENIGMA – is a consortium of 16 investigators at eleven institutions across the country led by Lawrence Berkeley Laboratory. Established in 2009, ENIGMA researchers collaborate to create a predictive model of the impacts of microbial communities on critical processes within the ecosystem. We study subsurface microbiomes within the contaminated Bear Creek aquifer at the Oak Ridge Reservation, a site with complex contaminants, generated by research and production of nuclear materials, including nitrate, acidity, uranium, technetium and volatile organic carbon species, the fate of which is influenced by the activity of subsurface microbial communities. We use sophisticated field experiments to discover and measure the natural and anthropogenically perturbed dynamics of geochemical and biological processes. From these we infer the chemical, physical and microbial interactions that predict these dynamics and estimate the ecological forces that shape microbial community function. We then use a unique array of culturing, genetic, physiological and imaging technologies to capture this diversity in the laboratory and understand the genetic basis for observed behaviors. Our goal is to provide an unprecedented mechanistic and predictive understanding of complex environmental bioprocesses with a focus on pH, oxygen, and metal-mediated carbon, nitrogen and sulfur cycling in the shallow subsurface of a contaminated watershed.