Radial growth (indices of tree-ring widths) of Eastern cottonwood (Populus deltoides Marsh.), a flood-tolerant species, and black walnut (Juglans nigra L)., a flood-intolerant species, were compared with climate and streamflow data by stepwise multiple regression for a riparian forest along the Olentangy River in central Ohio to investigate: (1) the influence of these variables on riparian primary productivity; and (2) whether these species can be used as predictors for the reconstruction of streamflow. Black walnut showed a significant growth response to streamflow. There was no relationship between growth of Eastern cottonwood and streamflow. Growth relationships with climate (mean monthly air temperature, total monthly precipitation) and Palmer Drought Severity Index (PDSI) showed black walnut growth on an upland riparian site was more sensitive to temperature and PDSI than on a lower-elevation site. Growth of black walnut on the low-elevation riparian site was directly and positively influenced by increased streamflow in midwinter and in late summer when subsurface soil moisture recharge from streamflow may be a critical moisture source. Growth of Eastern cottonwood on the low-elevation site was not related to streamflow, but was reduced by excess summer precipitation.