Shoreline and Water Quality Impacts from Recreational Boating on the Mississippi River
The rapid growth in the numbers and size of recreational boats is having serious ecological and social effects on the Upper Mississippi River System (UMRS). Environmental studies have shown that the height and frequency of waves generated by recreational traffic is the principal causal factor for the high rates of erosion affecting the entire streambank profile. Shorelines exposed to significant recreational boat traffic are eroding at an average rate of 2-3 feet/year. Over the period of a decade, this translates to a loss of 20-30 feet of main channel shoreland and the ecological values associated with the floodplain forest community. An estimate of sediment release to the river (Johnson 1997), from Lock and Dam 3 to the head of Lake Pepin, indicates that streambank erosion contributes 82,600 cubic yards of sediment annually. This is approximately four times the amount of sediment dredged annually from this reach for channel maintenance.
The discussion in this summary report focuses on upper Pool 4, defined as that river reach from Lock and Dam 3 to the head of Lake Pepin. Studies published by the Illinois State Water Survey and U. S. Fish and Wildlife Service, Environmental Management Technical Center developed information on wave and vessel characteristics, and shoreline and water quality impacts within this geographical setting. Because of the similarity in geological conditions in Pools 2, 3, and upper 4, study results are most directly applicable to these reaches of the Mississippi River. Protection and enhancement of the critically important ecological and social values of the river requires that local, state, federal, and private constituencies begin a collaborative process to identify and implement new management strategies. Water surface use authority rests with local governmental units in Minnesota, pointing to the important role county and municipal governments will play in their respective jurisdictions of the UMRS. The intent of this issue analysis document is to provide a basis and justification for responsible actions directed at the appropriate management of this great resource.
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