A summary of water quality characteristics in Navigation Pool 8 Schellhaass, S. M., and H. A. Langrehr. 1992. A summary of water quality characteristics at selected habitat sites in Navigation Pool 8 of the Mississippi River for 1 January-30 December 1989. Report by the Wisconsin Department of Natural Resources, La Crosse, Wisconsin, for the U.S. Fish and Wildlife Service, Environmental Management Technical Center, Onalaska, Wisconsin, December 1992. EMTC 92-S022. 47 pp. (NTIS # PB94-103538) ABSTRACT Five habitats were required to be sampled under the LTRMP: Channel Border Unstructured (CB-U), Channel Border - Wing Dam (CB-W), Backwater Contiguous (BW-C), Backwater Isolated (BW-I), and Impoundment (IMP). Similar weekly trends were seen in all five habitats during the year. Water clarity as indicated by nephelometric turbidity and Secchi disk depth transparency decreased from winter to summer, then increased during late summer and autumn. Dissolved oxygen (DO) showed similar trends in all habitats, as did temperature. A period of severe thunderstorms during the end of May produced sufficient runoff to increase flows in the river. All habitats experienced a very noticeable decrease in DO levels and a slight increase in average weekly turbidity and velocity values at that time. Data collected during comparable temporal periods in 1988 and 1989 showed similar trends in all habitats. Some differences in measurements during the same periods appeared to be a result of the severe drought conditions experienced during 1988. Average velocities were slightly greater in four habitats during 1989 than during 1988, probably a direct result of lower flows through the system. Conductivity was slightly greater in 1988 for all habitats, indicating a greater concentrating effect due to low flows and higher average temperatures during the summer. Contiguous backwaters commonly showed the greatest weekly range in DO, temperature, velocity, specific conductance, and Secchi disk transparency. This variability coincides with the diversity found in the physical and biological characteristics of Pool 8 contiguous backwater habitats. KEYWORDS aquatic, water quality, Mississippi, river, ecology, trend analysis