Environmental Changes Produced by Cold-Water Outlets from Three Arkansas Reservoirs

摘要

Water qualities of two natural streams (Buffalo and Kings Rivers), one new cold tailwater (Beaver), and two old cold tailwaters (Norfork and Bull Shoals) in northwestern Arkansas were studied from July 1965 through October 1968. The essential difference between the old cold tailwaters and natural streams is a change in water quality which allows the development of a new productive ecological environment. Features which typify the old tailwaters are as follows: (1) relatively homoiothermal temperatures; (2) stream beds scoured by strong hydroelectric power generation currents; (3) abundant phytoplankton and benthic macroinvertebrates; and (4) absence of warm water game fishes. Environmental factors characterizing natural streams are as follows: (1) high summer temperatures; (2) seasonal and individual current fluctuations at the various stations; (3) a greater variety of benthic macroinvertebrates and ichthyofauna; (4) abundant zooplankters; and (5) a tendency toward an equal distribution of the phyla Chrysophyta, Cyanophyta, and Chlorophyta. By October 1968, the new Beaver cold tailwater had lost all of its warm-water characteristics but had not developed the biotic features of the old tailwaters. (WRSIC abstract)