Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

•We examined salinity–discharge relationships for a semi-arid watershed.•Salinity had increased for a given discharge in 2009–2012 compared to 2005–2008.•The watershed has undergone increased oil and gas development.•The watershed contains soils with abundant native salts derived from marine shale.•Disturbance of these soils is the best explanation for the salinity increase.