From 1978 through 1980 the benthic macroinvertebrate and fish communities of three steam systems in Central Indiana were examined. The objective of this study was to describe the organization of these communities in relation to different land use. The influence of agriculture on the 14 stream segments ranged from virtually none to intense, and included some drainage from animal feed lots. The results of the study suggest the pattern of change caused by the increasing development of agriculture in small watershed streams. Initially agriculture may lead to an expanded biomass of fish and macroinvertebrates without causing a large compositional re-organization. This alteration may occur with little or no change in standing crop biomass. At this stage the density of non-chironomid insect larvae becomes reduced. The near-stream riparian part of the watershed is vital to the maintenance of healthy aquatic communities, acting as a buffer between plowed fields and farm animals and the aquatic system.