A Comprehensive Water Chemistry Dataset for Iranian Rivers.

River water quality data are essential for managing surface water resources and protecting terrestrial-aquatic ecosystems. While the number of compiled global river water quality datasets is growing, there is a notable lack of available data in Asian countries, especially Iran. To address this gap, this study compiled a comprehensive water chemistry dataset for Iranian rivers covering 1964-2020. The dataset includes 14 chemical compounds and 11 water quality indices, totaling 5,968,568 records (i.e., distinct measurement points × variables × time steps) obtained from 1,591 monitoring stations across the country's rivers. Our avialable chemical compounds include total dissolved solids, pH, electrical conductivity, carbonate, chloride, bicarbonate, sulfate, calcium, potassium, magnesium, sodium, nitrate, ΣCations, and ΣAnions. The calculated water quality indices in our dataset were sodium adsorption ratio, Larson index, sodium percentage, Kelly's ratio, total hardness, residual sodium carbonates, magnesium hazard, chloro-alkaline index, corrosivity ratio, permeability index, and saturation index. This dataset can support large-scale river water quality assessment studies at the national level and complement the available global river water quality databases.