The flow and dissolved iron content of two small streams draining a woodland basin and a recently deforested basin on a granite pluton in Kershaw County, South Carolina, were measured biweekly from September 1974 through August 1975. During spring and summer the flow of the stream draining the deforested basin was reduced relative to that of the woodland basin because of the higher transpiration associated with rapid biomass accumulation by the newly established vegetation in the deforested basin. The observed relative reduction in flow was accompanied by a relative increase in iron concentration in the flow from the deforested basin. Analysis of the data also indicates that the rate of export of dissolved iron from both basins is independent of stream discharge. These observations suggest that the dissolved iron content of these streams is controlled by the dilution of iron‐rich groundwater by essentially iron‐free surface runoff and shallow interflow. A simple mixing model based on this hypothesis has been developed and found to fit the d