Waves generated by recreational traffic: Part II Bhowmik, N. G., and T. W. Soong. 1992. Waves generated by recreational traffic: Part II, Uncontrolled movement. Report by the Illinois State Water Survey, Champaign, Illinois, for the U.S. Fish and Wildlife Service, Environmental Management Technical Center, Onalaska, Wisconsin, December 1992. EMTC 92-S016. 24 pp. (NTIS #PB94-110531) ABSTRACT This paper presents the results of a research project undertaken to determine the wave characteristics generated by the uncontrolled movement of recreational boats on the Upper Mississippi River System (UMRS). Recorded boating events from a section of the Mississippi River indicated that as many as 704 boats (up to 120 boats per hour) passed this highly used area of the UMRS in a single day during a busy weekend. Sustained movement of recreational boats can generate essentially continuous waves at the shoreline. During the day of heaviest boating activity at the Mississippi River site, the maximum wave height measured was 0.52 m, which was similar to the maximum wave height values reported in Part I. Analyses of the wave heights on an hourly basis indicated that significant wave height can reach a magnitude of 0.4 m or higher, and maximum wave height can reach 0.5 m or higher. For waves of 0.4 m in height to develop at the Red Wing site from wind alone, the wind would have to be blowing at a speed of about 26 m per second (58 mph) across the measuring point. Wave energies were computed by segmenting the wave data in 5-minute intervals. These analyses showed that the shorelines are subjected to wave activity of fairly high intensity. KEYWORDS waves, recreational boats, Upper Mississippi River System, Mississippi River