The dataset contains physical, chemical and biological measurements from the waters of 21 river sites across the Red River Delta in northern Vietnam. The data were collected monthly between February 2018 and January 2020. The parameters include temperature, dissolved oxygen, salinity, pH, turbidity, conductivity, total dissolved solids, dissolved nitrate, dissolved nitrite, dissolved ammonium, total nitrogen, dissolved phosphate, dissolved silicate, alkalinity, dissolved major ions (sodium, magnesium, potassium, calcium, chloride, sulphate) and a range of chlorophyll and carotenoid pigments from riverine seston.