Salinity is an important metric in measuring the health of a watershed. The ionic composition of a river reflects both naturally occurring features and events--such as geological composition and meteorological phenomena—and anthropogenic activities like farming and road maintenance. Unusually high concentrations of salts in a body of fresh water can harm populations dependent on the river, and thus the determination of inputs of salinity to a river system becomes important for ensuring the general health of a region. In this study, we measure different water quality parameters--such as pH, dissolved oxygen content, and E. Coli content—and investigate potential inputs of salts to the Westfield River, focusing on groundwater, tributary, anthropogenic, and evaporative influences. Concentrations of cations were determined via atomic absorption/emission spectroscopy and concentrations of anions were determined through ion chromatography. To measure the effect of evaporation on river salinity, a meteoric water line was generated from the isotopic composition of water samples collected in the watershed. Based on the meteoric water line constructed, we conclude that evaporation played a minimal role in concentrating salts in the Westfield River during the sample collection period. Similarly, groundwater flow appears to minimally impact the salt concentrations of the Westfield River, however, it does seem to be the primary contributor of carbonate and bicarbonate ions. The spatial variation in salinity data indicates that tributaries and anthropogenic activities raise the salinity of the mainstem Westfield River.