The results of a 1965-66 study of the physico-chemical factors, benthic macroinvertebrates, plankton, and fishes of three cold tailwaters (Bull Shoals, Norfork and Beaver) were published in the Proceedings of the Annual Conference of the Southeastern Association of Game and Fish Commissioners by Brown, Liston, and Dennie (1967). The data presented here are an extension of this work and compare the macroinvertebrates of two natural streams (Buffalo and Kings rivers), two old tailwaters (Bull Shoals and Norfork), and a new tailwater (Beaver, impounded in 1963). The dominant groups of benthic macroinvertebrates in the older tailwaters, Bull Shoals and Norfolk, were Isopoda, Chironomidae, Amphipoda, and Oligochaeta. The 1967-68 data show that the Beaver Tailwater just below the dam had fewer organisms per square foot than comparable stations below the older Bull Shoals and Norfork tailwaters and the same stations on the Beaver tailwater during the 1965-66 study. The data also indicate that Chironomidae have become relatively more abundant at all stations in the Beaver tailwater since the earlier study. Isopoda have increased at the first station below Beaver Dam while Oligochaeta decreased at all stations. Trichoptera, Coleoptera, Ephemeroptera, and Gastropoda were abundant in one or both natural streams. The Coleoptera dominated the Buffalo River samples and Ephemeroptera and Trichoptera were most abundant in the Kings River.
