Field experiments were performed to obtain first-step estimates of the effects of selected chemical dispersant agents (OFC D-609 and Corexit 9550) on the behavior and retention of spilled crude oil in a shallow freshwater streambed environment in southcentral Alaska. Comparisons between experiments with and without prespill additions of dispersants to the oil included measurements of oil in sediment and water samples. Sediment and water contamination by oil was quantified by flame ionization detector capillary gas chromatography (FID-GC) as well as visual observations in the simulated streambed channel following the spill events. Inclusion of dispersants in the oil produced the intended result of enhancing dispersion of oil into the aqueous phase. However, distributions of oil in aqueous and sediment samples were controlled by interactions between a variety of factors including rheological properties of the oil (for example, oil/water interfacial surface tension values), particle size distributions of sediment matrices, exposure of sediment surfaces to oil, and in situ water flow characteristics at specific streambed channel sites. The results imply that use of chemical dispersants to mitigate effects of oil spills in freshwater streambed environments must include an understanding of the interplay between variables related to both the type of oil released and the specific streambed environment.