Riley began his career with the USGS in 2015 at the California Water Science Center in San Diego.
His main research interests include isotope geochemistry, paleoclimate reconstructions, and groundwater contamination. He has primarily worked on the San Diego Hydrogeology (SDH) project and the California Oil, Gas, and Groundwater (COGG) program. Topics have included:
- mapping paleo river channels using acoustic and geologic data (SDH)
- reconstructing paleo precipitation records using groundwater chemistry, model output, and speleothems (SDH)
- calculating natural streamflow by removing reservoirs and other anthropogenic effects (SDH)
- database management (COGG)
- physical and chemical characterization of hydraulically fractured wells (COGG)
- study unit analysis of oilfield activities and their possible influence on groundwater resources (COGG)