Water quality, habitat structure, and macroinvertebrate and fish communities were surveyed in 1979-1980 in ten headwater streams of the Cedar River basin. All streams are affected by moderate to intensive agricultural land use in their watersheds, and the purpose of the study was to describe stream ecological changes caused by this influence. Most streams carried heavy sediment and nutrient loads, had fine-particulate substrates, were extensively channelized, had a wide range in daily flows, and were largely devoid of instream vegetation. Water quality was highest and habitat structure was most complex in a woodland stream, and a pattern of environmental differences was measured among the nine prairie streams. Ten fish species, mainly minnows, were identified as fish community dominants in all streams.