Water quality characteristics in Navigation Pool 4 of the Mississippi River, 1990 Burdis, R. M. 1997. Water quality characteristics in Navigation Pool 4 of the Mississippi River, 1990. U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, December 1997. LTRMP 97-S002. 25 pp. (NTIS #PB98-130883) ABSTRACT Resource Trend Analysis water quality monitoring was initiated in Navigation Pool 4 of the Upper Mississippi River in January 1990 as part of the Long Term Resource Monitoring Program. Water quality sampling was conducted in different habitats of the Upper Mississippi River System to interpret and predict short-term variability and long-term trends. KEYWORDS Dissolved oxygen, Environmental Management Program, Lake Pepin, Long Term Resource Monitoring Program, Minnesota, monitoring, Wisconsin