Water and sediment component annual report, Pool 13, 1989 Gent, R. D., M. J. Steuck, D. E. Gould, M. K. Griffin, and S. A. Gritters. 1996. Upper Mississippi River System Long Term Resource Monitoring Program water and sediment component annual report, Pool 13, 1989. Report by the Iowa Department of Natural Resources, Bellevue, Iowa, for the National Biological Service, Environmental Management Technical Center, Onalaska, Wisconsin, September 1996. LTRMP 96-S002. 46 pp. (NTIS # PB97-103758) ABSTRACT Resource Trend Analysis water quality sampling in Upper Mississippi River Pool 13 was initiated in August 1988 as a part of the Long Term Resource Monitoring Program. Mississippi Monitoring Station personnel continued water quality sampling in Pool 13 throughout 1989 using equipment and techniques consistent with the Procedures Manual for the Long Term Resource Monitoring Program (LTRMP). A total of 8,382 observations were recorded by the LTRMP water quality component in Pool 13 during the sampling period January 1 through December 31, 1989. Data collected in 1989 reflect water quality characteristics during a second consecutive year of low water conditions. Mean dissolved oxygen (DO) concentrations were higher in channel-associated habitats than in backwater habitats. Dissolved oxygen concentrations were typically above the 5.0 mg/L threshold established by the LTRMP to support healthly aquatic life. However, oxygen depletion was noted in backwater contiguous habitat at both shallow and deep water sites. Nephelometric turbidity, Secchi disk transparency, and current velocity values are linked to discharge rate through Lock and Dam 12. Turbidity exhibited a positive relationship to discharge, especially in channel-associated habitats. Turbidity in backwater habitats was influenced by peak spring discharges, but wind fetch and fish activity influenced turbidity peaks during summer and fall periods. Secchi disk transparency correlated to turbidity values. Current velocity observations in channel-associated habitats were positively correlated to Lock and Dam 12 discharges, while backwater habitats exhibited negligible velocities except during peak discharges. Similar specific conductance was observed among all habitats throughout the sampling period. Comparisons of 1988 and 1989 data revealed minimal differences in all water quality variables. Nephelometric turbidity and DO values were influenced by the presence of aquatic macrophyte during peak biomass in backwater contiguous and impounded habitats. KEYWORDS backwater habitat, Pool 13, Upper Mississippi River, water quality