Geology Guest Speaker Dr. Dan EngstromMay 9, 2012 at 10:30 a.m. to noon

Dr. Dan Engstrom will give a lecture entitled "The Dirt on Sediment Pollution in the Upper Mississippi River." Dr. Dan Engstrom is the Director of the Science Museum of Minnesota's St. Croix Watershed Research Station, where he has helped lead recent efforts to understand sediment pollution in the Minnesota River. Human activity has dramatically altered the natural landscape of Minnesota since the onset of European settlement some 200 years ago. Nowhere are these changes more clearly manifest than in the upper Mississippi River, where the combined effects of agriculture, urbanization, and hydrological alteration have severely impacted water quality. Until recently, the magnitude of these changes were not clear, because the early historical condition of the River was never measured or recorded. Now, using state of the art geochemical methods, Dr. Engstrom and colleagues have reconstructed a detailed account of the upper Mississippi River from the sediments accumulating in Lake Pepin. The results of these studies quantify the immense increases in sediment, nutrient, and pollutant inputs to the river that have accompanied the human transformation of the river's watershed. This presentation will focus on the changing sediment load, its sources, and the causes for a nearly 10-fold increase in the inputs to Lake Pepin. This increase has greatly shortened the projected life-span of the lake and severely degraded the habitat and recreational value of the upper Mississippi River.