To investigate the main factors that control the dissolved radiocesium concentration in riverwater in the area affected by the Fukushima Daiichi nuclear power plant accident, the correlations between the dissolved Cs-137 concentrations at 66 sites normalized to the average Cs-137 inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs-137 concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs-137 are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs-137 concentration. One reason for thiswould be because the high concentrations of solutes, such as K+ and dissolved organic carbon, discharged in urban areas would inhibit Cs-137 absorption to soil particles. A multiple regression equation was constructed to predict the normalized dissolved Cs-137 concentration with the topography, land use, soil component, and water quality data as explanatory variables. The bestmodel had the building land use as the primary predictor. When comparing twomultiple regression models inwhich the explanatory variables were limited to (1) the land use and soil composition and (2) the water quality, the water quality model underestimated the high normalized dissolve Cs-137 concentration in urban areas. This poor reproducibility indicates that the dissolved Cs-137 concentration value in urban areas cannot be solely explained by the solid-liquid distribution of Cs-137 owing to the influence of the water quality, but some specific Cs-137 sources in urban areas would control the dissolved Cs-137 concentration. (C) 2019 The Authors. Published by Elsevier B.V.