JoRee LaFrance

This project seeks to characterize the concentrations of organic and inorganic pollutants in the Little Bighorn River on the Crow Reservation in southeastern Montana as a function of discharge throughout the hydrologic year.  These “concentration-discharge relationships” are being resolved by coalescing discharge data, in situ multiparameter EXO2 sonde data, high frequency sample collection, and chemical analyses in the Arizona Laboratory for Emerging Contaminants for samples collected in upper and lower river reaches. Analytes being investigated include up to 25 per- and polyfluoroalkyl substances (PFAS), major anions and cations, dissolved organic matter, and metal(loid)s. Resolving the impacts of hydrologic controls over contaminant concentrations Little Bighorn River watershed is important to understanding the processes affecting surface water quality, their impacts on tribal water uses, and for informing tribal water policy.